National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: January 5, 2006 (Volume 71, Number 3)]
[Rules and Regulations]
[Page 703-752]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr05ja06-6]

[[pp. 703-752]]
National Primary Drinking Water Regulations: Long Term 2
Enhanced Surface Water Treatment Rule

[[Continued from page 702]]

[[Page 703]]

test based on the feed and filtrate concentrations of the challenge
particulate for that module. The individual LRVs for each module are
used to determine the overall removal efficiency of the membrane
product. If fewer than twenty modules are tested, the overall removal
efficiency is assigned a value equal to the lowest of the
representative LRVs for the various modules tested. If twenty or more
modules are tested, then the overall removal efficiency is assigned a
value equal to the 10th percentile of the representative LRVs for the
various modules tested.
? As part of the challenge test, a quality control release
value (QCRV) must be established for a non-destructive performance test
(e.g., bubble point test, diffusive airflow test, pressure/vacuum decay
test) that demonstrates the Cryptosporidium removal capability of the
membrane module. The non-destructive performance test must be applied
to each membrane module a PWS uses in order to verify Cryptosporidium
removal capability. Membrane modules that do not meet the established
QCRV are not eligible for the Cryptosporidium removal credit
demonstrated during challenge testing.
If a previously tested membrane product is modified in a manner
that could change the removal efficiency of the membrane or the
applicability of non-destructive performance test and associated QCRV,
the modified membrane filter must be challenge tested to establish the
removal efficiency and QCRV. If approved by the State, data from
challenge testing conducted prior to promulgation of today's rule may
be considered in lieu of additional testing. However, the prior testing
must have been conducted in a manner that demonstrates a removal
efficiency for Cryptosporidium commensurate with the treatment credit
awarded to the filter.

Membrane Direct Integrity Testing

In order to receive Cryptosporidium treatment credit for a membrane
filtration process, PWSs must conduct direct integrity testing in a
manner that demonstrates a removal efficiency equal to or greater than
the removal credit awarded to the membrane filtration process. A direct
integrity test is defined as a physical test applied to a membrane unit
in order to identify and isolate integrity breaches (i.e., one or more
leaks that could result in contamination of the filtrate).
Each membrane unit must be independently direct integrity tested,
where a membrane unit is defined as a group of membrane modules that
share common valving which allows the unit to be isolated from the rest
of the system for the purpose of integrity testing or other
maintenance. The direct integrity test must be applied to the physical
elements of the entire membrane unit including membranes, seals,
potting material, associated valving and piping, and all other
components which under compromised conditions could result in
contamination of the filtrate.
Common direct integrity tests include those that apply pressure or
vacuum (such as the pressure decay test and diffusive airflow test) and
those that measure the rejection of a particulate or molecular marker
(such as spiked particle monitoring). Today's final rule does not
stipulate the use of a particular direct integrity test. Instead, the
direct integrity test must meet performance criteria for resolution,
sensitivity, and frequency.
``Resolution'' is defined as the smallest leak that contributes to
the response from a direct integrity test. Any direct integrity test
applied to meet the requirements of this rule must have a resolution of
3 micrometers or less. The manner in which resolution is determined
will depend on the type of direct integrity test used (i.e., pressure-
based versus marker-based tests).
``Sensitivity'' is defined as the maximum LRV that can be reliably
verified by the direct integrity test. The sensitivity of the direct
integrity test applied to a membrane filtration process to meet the
Cryptosporidium treatment requirements of this rule must be equal to or
greater than the removal credit awarded to the membrane filtration
process. Furthermore, the increased concentration of suspended solids
that occurs on the high pressure side of the membrane in some module
designs must be considered in the sensitivity determination (i.e., the
scouring action of some membrane designs keeps the accumulated solids
in suspension where they may pass through an integrity breach).
Specifically, the sensitivity of the direct integrity test is reduced
by a factor that quantifies the increased concentration of suspended
solids relative to the feed concentration.
The ``frequency'' of direct integrity testing specifies how often
the test is performed over an established time interval. Direct
integrity tests available at the time of promulgation are applied
periodically and must be conducted on each membrane unit at a frequency
of not less than once per day that the unit is in operation, unless the
State determines that less frequent testing is acceptable. If
continuous direct integrity test methods become available that also
meet the sensitivity and resolution criteria described earlier, such a
continuous test may be used in lieu of periodic testing.
PWSs must establish a direct integrity test control limit that is
indicative of an integral membrane unit capable of meeting the
Cryptosporidium removal credit awarded to the membrane. If the control
limit for the direct integrity test is exceeded, the membrane unit must
be taken off-line for diagnostic testing and repair. The membrane unit
may only be returned to service after the repair has been completed and
confirmed through the application of a direct integrity test. A monthly
report must be submitted to the State summarizing all direct integrity
test results above the control limit and the corrective action that was
taken in each case.

Continuous Indirect Integrity Monitoring

Available direct integrity test methods are applied periodically
since the membrane unit must be taken out of service to conduct the
test. In order to provide some measure of process performance between
direct integrity testing events, PWSs must perform continuous indirect
integrity monitoring on each membrane unit. Continuous indirect
integrity monitoring is defined as monitoring some aspect of filtrate
water quality that is indicative of the removal of particulate matter
at a frequency of at least once every 15 minutes. If a continuous
direct integrity test is implemented that meets the resolution and
sensitivity criteria described previously in this section, continuous
indirect integrity monitoring is not required.
Unless the State approves an alternative parameter, continuous
indirect integrity monitoring must include continuous filtrate
turbidity monitoring. If the filtrate turbidity readings are above 0.15
NTU for a period greater than 15 minutes, the PWS must perform direct
integrity testing on the associated membrane unit.
If the State approves an alternate parameter for continuous
indirect integrity monitoring, the State must approve a control limit
for that parameter. If the parameter exceeds the control limit for a
period greater than 15 minutes, the PWS must perform direct integrity
testing on the associated membrane unit.
PWSs must submit a monthly report to the State summarizing all
continuous indirect integrity monitoring results triggering direct
integrity testing and the corrective action that was taken in each case.
EPA has developed the Membrane Filtration Guidance Manual to assist

[[Page 704]]

systems with implementation of these requirements. This guidance may be
requested from EPA's Safe Drinking Water Hotline, which may be
contacted as described under FOR FURTHER INFORMATION CONTACT in the
beginning of this notice.
b. Background and Analysis
In the August 11, 2003 proposed LT2ESWTR, EPA proposed to establish
criteria for awarding credit to membrane filtration processes for
removal of Cryptosporidium (USEPA 2003g). The Agency based these
criteria on data demonstrating the Cryptosporidium removal efficiency
of membrane filtration processes, a critical evaluation of available
integrity monitoring techniques, and study of State approaches to the
regulation of membrane filtration for pathogen removal. This
information is summarized in the report Low-Pressure Membrane
Filtration for Pathogen Removal: Application, Implementation, and
Regulatory Issues (USEPA 2001g).
As summarized in this report, a number of studies demonstrate the
ability of membrane filtration processes to remove pathogens, including
Cryptosporidium, to below detection levels (USEPA 2001g). In some
studies that used Cryptosporidium seeding, measured removal
efficiencies were as high as 7-log (Jacangelo, et al., 1997; Hagen,
1998; Kachalsky and Masterson, 1993). In other studies, removal
efficiencies ranged from 4.4- to 6.5-log and were only limited by the
seeded concentration of Cryptosporidium oocysts (Dwyer, et al. 1995,
Jacangelo et al. 1989, Trussel, et al. 1998, NSF 2000a-g, Olivieri
1989). Collectively, these results demonstrate that an integral
membrane module (i.e., a membrane module without any leaks or defects,
with an exclusion characteristic smaller than Cryptosporidium) is
capable of removing this pathogen to below detection in the filtrate,
independent of the influent concentration.
The 2003 proposal included a provision for challenge testing
membranes to demonstrate the removal efficiency of Cryptosporidium. EPA
believes this requirement is necessary due to the proprietary nature of
these products and the lack of any uniform design criteria for
establishing the exclusion characteristic of a membrane. Guidance on
the design and conduct of a challenge test to meet the requirements of
this rule is presented in the Membrane Filtration Guidance Manual.
Challenge testing is required on a product-specific basis, rather
than a site-specific basis; thus, modules used in full-scale facilities
will generally not be directly challenge tested. The removal capability
of production membrane modules is verified through the application of a
non-destructive performance test, such as a bubble point test. A
quality control release value (QCRV) for the non-destructive
performance test can be related to the results of the challenge test
and used to demonstrate the ability of production modules to achieve
the Cryptosporidium removal efficiency demonstrated during challenge
testing. Most membrane manufacturers have adapted some form of non-
destructive testing for the purpose of product quality control and have
established a QCRV that is indicative of an acceptable product. It may
be possible to apply these existing practices to meet the requirements
of today's final rule.
While challenge testing demonstrates the removal efficiency of an
integral membrane module, defects or leaks in the membrane or other
system components can result in contamination of the filtrate unless
they are identified, isolated, and repaired. In order to verify
continued performance of a membrane system, today's final rule requires
direct integrity testing of membrane filtration processes used to meet
the Cryptosporidium treatment requirements of this rule.
An evaluation of available direct integrity tests indicates that
pressure-based tests are widely applied and sufficiently sensitive to
provide verification of removal efficiencies in excess of 4-log.
Marker-based direct integrity tests are also available, and new direct
integrity tests may be developed that present an improvement over
existing tests. Rather than specify a particular direct integrity test,
today's final rule defines performance criteria for direct integrity
testing. These criteria are resolution, sensitivity, and frequency, as
previously described. EPA believes that this approach will provide
flexibility for the development and implementation of future
innovations in direct integrity testing while ensuring that any test
applied to meet the requirements of this rule will achieve the required
level of performance.
Since available direct integrity tests require taking the membrane
unit out of service to conduct the test, today's rule establishes a
minimum test frequency for direct integrity testing. Currently, there
is no standard frequency for direct integrity testing that has been
adopted by all States and membrane treatment facilities. In a 2000
survey, the required frequency of integrity testing was found to vary
from once every four hours to once per week; however, the most common
frequency for conducting a direct integrity test was once every 24
hours (USEPA 2001g). Specifically, 10 out of 14 States that require
periodic direct integrity testing specify a frequency of once per day.
Furthermore, many membrane manufacturers of systems with automated
integrity test systems set up the membrane units to automatically
perform a direct integrity test once per day.
EPA believes that daily direct integrity testing is appropriate for
most membrane filtration installations, but under some circumstances,
less frequent testing may be adequate. Thus, EPA is allowing States to
approve less frequent direct integrity testing on the basis of
demonstrated process reliability, use of multiple barriers effective
for Cryptosporidium, or reliable process safeguards.
Due to the periodic nature of direct integrity testing, today's
rule includes a provision for continuous indirect integrity monitoring.
While indirect monitoring is not as sensitive as direct testing, it
provides an indication of process performance to ensure that a major
failure has not occurred between application of direct integrity tests.
c. Summary of Major Comments
In response to the 2003 proposal, the Agency received significant
comments on the following issues related to membrane filtration: the
frequency of direct integrity testing; the procedure necessary to
determine removal credit for membrane filtration; and the requirement
for continuous indirect integrity monitoring.
The 2003 proposal requested comment on the proposed minimum direct
integrity test frequency of once per day. Some commenters supported the
daily frequency and commented that many states have already adopted
this standard. Others commented that direct integrity testing once per
day is too frequent, citing the lack of data in the proposal documenting
the rate of membrane failure, as well as the loss in production that
occurs when the membrane unit is taken off-line for testing.
While EPA recognizes these concerns, a critical factor in
establishing a testing frequency is the amount of time that water from
a compromised membrane unit is supplied to the public before the
integrity breach is detected. EPA believes that this factor is most
important to public health protection and that daily direct integrity
testing is appropriate for the majority of membrane systems. However,
EPA also acknowledges that there may be

[[Page 705]]

circumstances under which less frequent testing may provide adequate
public health protection, and has revised the rule to allow States to
permit less frequent direct integrity testing based on demonstrated
process reliability, use of multiple barriers effective for
Cryptosporidium, or reliable process safeguards.
Several commenters expressed concern with the process needed to
determine appropriate removal credit for membrane filtration. However,
many commenters also supported the flexibility provided to States in
determining the appropriate removal credit for membrane filtration
based on the criteria defined in the 2003 proposal. EPA believes that
the proposed approach for awarding Cryptosporidium removal credit to
membrane filtration is supported by the available data and analysis,
and will allow higher removal credits to be considered on a
scientifically sound basis. EPA recognizes that the flexibility
provided in the regulation does increase the complexity of determining
removal credits for membrane filtration. To address this issue, EPA has
developed extensive guidance to support the implementation of
requirements for membrane filtration.
EPA received comment that continuous indirect integrity monitoring
is unnecessary due to the poor sensitivity of currently available
methods. EPA acknowledges that currently available indirect monitoring
methods are less sensitive than available direct integrity tests.
However, EPA believes that continuous indirect integrity monitoring is
necessary to protect public health. Specifically, continuous monitoring
may alert a system of potentially severe integrity breaches that could
result in bypass of unfiltered water around the membrane filtration
process and pose a risk to public health. Furthermore, EPA has provided
States with the flexibility to permit use of more sensitive continuous
indirect monitoring methods and/or to establish lower control limits.
Also, implementation of continuous direct integrity testing would
preclude the need to implement any form of indirect integrity monitoring.
12. Second Stage Filtration
a. Today's Rule
PWSs may receive 0.5-log credit towards the Cryptosporidium
treatment requirements of today's rule for a second filtration stage.
To be eligible for this credit, the second-stage filtration must meet
the following criteria:
? The filter must be a separate second stage of granular
media filtration, such as sand, dual media, or granular activated
carbon (GAC), that follows a first stage of granular media filtration
(e.g., follows a conventional treatment or direct filtration plant).
? The first filtration stage must be preceded by a coagulation process.
? Both filtration stages must treat 100 percent of the
treatment plant flow.
? The State must approve the treatment credit based on an
assessment of the design characteristics of the filtration process.
This microbial toolbox option does not apply to bag filters,
cartridge filters, membranes, or slow sand filters, which are addressed
separately in the microbial toolbox. Further, this options does not
apply to roughing filters, which are pretreatment processes that
typically consist of coarse media and are not preceded by coagulation.
States may consider awarding treatment credit to roughing filters under
a demonstration of performance.
PWSs may not receive additional treatment credit for both second-
stage filtration and lower filter effluent turbidity (i.e., combined or
individual filter performance) that is based on turbidity levels
following the second filtration stage. PWSs may receive credit for both
options based on turbidity following the first filtration stage.
b. Background and Analysis
The Stage 2 M-DBP Advisory Committee recommended a 0.5-log
Cryptosporidium treatment credit for a roughing filter with the
stipulation that EPA identify the design and operational conditions
under which such credit is appropriate. After reviewing available data,
however, EPA was unable to determine conditions under which a roughing
filter is likely to achieve at least 0.5-log removal of
Cryptosporidium. Roughing filters consist of coarse media like gravel
and usually are not preceded by coagulation. They are used to remove
sediment and large particulate matter from raw water prior to the
primary treatment processes. EPA identified no studies indicating that
roughing filters would be effective for removal of Cryptosporidium
(USEPA 2003a).
In contrast, numerous studies have demonstrated that granular media
filtration can be effective for removing Cryptosporidium when preceded
by coagulation (Patania et al. 1995, Nieminski and Ongerth 1995,
Ongerth and Pecoraro 1995, LeChevallier and Norton 1992, LeChevallier
et al. 1991, Dugan et al. 2001, Nieminski and Bellamy 2000, McTigue et
al. 1998, Patania et al. 1999, Huck et al. 2000, Emelko et al. 2000).
PWSs may implement a second granular media filtration stage to achieve
various water quality objectives, such as increased removal of organic
material in biologically active filters or removal of inorganic
contaminants. Consequently, EPA believes that consideration of
additional Cryptosporidium treatment credit for a second granular media
filtration stage is appropriate.
The August 11, 2003 LT2ESWTR proposal included an additional 0.5-
log Cryptosporidium treatment credit for PWSs that use a second
separate filtration stage consisting of rapid sand, dual media, GAC, or
other fine grain media. A cap, such as GAC, on a single stage of
filtration did not qualify. In addition, the proposal required the
first stage of filtration to be preceded by a coagulation step and both
stages had to treat 100 percent of the plant flow. Today's final rule
establishes this treatment credit with minimal changes from the
proposal. The basis for this credit and for changes from the proposed
rule are summarized in the following discussion.
While the studies of Cryptosporidium removal by granular media
filtration cited previously evaluated only a single stage of
filtration, the same removal mechanisms will be operative in a second
stage of granular media filtration. Secondary filters may remove
Cryptosporidium that were destabilized but not trapped in primary
filters or that were trapped but subsequently detached from primary
filters prior to backwash. Thus, EPA believes these studies are
supportive of additional removal credit for a second filtration stage.
An important finding of these studies is that coagulation is
necessary to achieve significant Cryptosporidium removal by granular
media filtration (does not apply to slow sand filtration, which is
addressed in the next section). Consequently, today's rule requires
that the first filtration stage be preceded by coagulation for a PWS to
receive treatment credit for second-stage filtration. This requirement
is necessary to ensure that both filtration stages are effective for
Cryptosporidium removal. PWSs will already comply with this requirement
where a second filtration stage is applied after conventional treatment
or direct filtration.
In the proposal, EPA also reviewed data provided by a PWS on the
removal of aerobic spores through GAC filters (i.e., contactors)
following conventional treatment. As discussed earlier, studies have
demonstrated that aerobic spores can serve as an indicator of
Cryptosporidium removal by granular

[[Page 706]]

media filtration (Dugan et al. 2001, Emelko et al. 1999 and 2000, Yates
et al. 1998, Mazounie et al. 2000). Over a two year period, the mean
removal of aerobic spores across the GAC filters exceeded 0.5-log.
These results support the finding that a second stage of granular media
filtration can reduce Cryptosporidium levels by 0.5-log or greater.
Today's rule does not establish design criteria such as filter
depth or media size for second-stage filters to be eligible for
treatment credit. While filter design will influence Cryptosporidium
removal efficiency, EPA recognizes that appropriate filter designs will
vary depending on the application. States have traditionally provided
oversight for treatment process designs in PWSs. Accordingly, today's
rule requires State review and approval of second-stage filter design
as a condition for PWSs to receive additional treatment credit for this
process. The Microbial Toolbox Guidance Manual addresses second-stage
filtration for Cryptosporidium treatment credit.
c. Summary of Major Comments
Public comment on the August 11, 2003 LT2ESWTR proposal generally
supported additional treatment credit for second-stage filtration.
Commenters raised specific concerns with EPA establishing design
requirements for filtration, the sufficiency of data to support
prescribed treatment credit, and the expansion of this credit to
include other filtration technologies. These comments and EPA's
responses are summarized as follows.
In the proposal, EPA requested comment on whether a minimum filter
depth should be required for PWSs to receive treatment credit for a
second filtration stage. All commenters opposed EPA setting regulatory
design standards for filters on the basis that PWSs and States need the
flexibility to determine appropriate treatment designs. In response,
EPA agrees that effective filter designs will vary depending on the
application. Consequently, EPA is not establishing filter design
criteria in today's rule, but is requiring that States approve designs
for PWSs to receive treatment credit for second-stage filtration.
Many commenters stated that available data support the prescribed
0.5-log Cryptosporidium treatment credit for second-stage filtration.
Some commenters provided additional data on the removal of aerobic
spores through GAC filters following conventional treatment that showed
a mean reduction greater than 1-log. In contrast, other commenters were
concerned about the lack of data to support increased removal through a
second filtration stage. These commenters recommended that treatment
credit for second-stage filtration should be awarded only on a site-
specific basis through a demonstration of performance.
EPA has concluded that available data are sufficient to support the
prescribed 0.5-log treatment credit for second-stage filtration.
Studies of granular media filtration demonstrate high levels of
Cryptosporidium removal and one study has shown greater than 1.0-log
removal through secondary GAC filters. Secondary filters can remove
Cryptosporidium that pass through or detach from the primary filters.
This added removal will help to stabilize finished water quality by
providing a barrier during periods of the filtration cycle when the
primary filters are not performing optimally. Therefore, EPA is
establishing this credit in today's rule.
Several commenters recommended that EPA expand the second-stage
filtration option to include membranes, bag filters, and DE filtration.
EPA notes that today's rule establishes prescribed treatment credits
specifically for bag and cartridge filters and membranes as microbial
toolbox options, and prescribed credit for DE filtration is addressed
in section IV.B. PWSs may seek treatment credit for other filtration
technologies through a demonstration of performance under today's rule.
13. Slow Sand Filtration
a. Today's Rule
PWSs may receive a 2.5-log credit towards the Cryptosporidium
treatment requirements in today's rule for implementing slow sand
filtration as a secondary filtration stage following a primary
filtration process. To be eligible for this credit, the slow sand
filtration must meet the following criteria:
? The slow sand filter must be a separate second stage of
filtration that follows a first stage of filtration like conventional
treatment or direct filtration;
? There must be no disinfectant residual in the influent
water to the slow sand filtration process;
? Both filtration stages must treat 100 percent of the
treatment plant flow from a surface water or GWUDI source; and
? The State must approve the treatment credit based on an
assessment of the design characteristics of the filtration process.
Slow sand filtration used as a primary filtration process receives
a prescribed 3-log Cryptosporidium treatment credit, as described in
section IV.B.
b. Background and Analysis
Slow sand filtration is a process involving passage of raw water
through a bed of sand at low velocity (generally less than 0.4 m/h),
resulting in substantial particulate removal. Several studies have
demonstrated that slow sand filtration can achieve significant
Cryptosporidium removal (Schuler and Ghosh, 1991, Timms et al. 1995,
Hall et al. 1994). Slow sand filtration is typically used as a primary
filtration process, usually in small systems, rather than as a
secondary filtration stage following conventional treatment or another
primary filtration process. EPA expects, however, that slow sand
filtration would be effective for Cryptosporidium removal in such an
application, which warrants consideration of treatment credit under
today's rule.
The Stage 2 M-DBP Advisory Committee recommended that slow sand
filtration receive 2.5-log or greater Cryptosporidium treatment credit
when used in addition to existing treatment that achieves compliance
with the IESWTR or LT1ESWTR. The August 11, 2003 LT2ESWTR proposal
included 2.5-log treatment credit for slow sand as a secondary
filtration process, with the only associated condition being no
disinfectant residual in the water influent to the filter. In today's
rule, EPA is establishing this treatment credit with minimal changes
from the proposal. The following discussion summarizes the basis for
this credit and for changes from the proposal.
Removal of microbial pathogens in slow sand filters is complex and
is believed to occur through a combination of physical, chemical, and
biological mechanisms, both on the surface and in the interior of the
filter bed. In particular, biological activity in the upper layers of
the filter is believed to promote microbial removal. Based on
previously cited studies demonstrating greater than 4-log removal of
Cryptosporidium through slow sand filtration, today's rule awards a
prescribed 3-log Cryptosporidium removal credit to slow sand filtration
as a primary filtration process.
The effectiveness of slow sand as a secondary filtration process is
more uncertain. In general, EPA expects that the same microbial removal
mechanisms will be operative. However, due to the quality of treated
water following a primary filtration process, filter ripening and
development of the biologically active layer in a secondary slow sand
filter may be inhibited. One study that evaluated Cryptosporidium
removal by slow sand filtration alone

[[Page 707]]

and slow sand filtration preceded by a rapid sand filter observed
similar removal levels in the two treatment trains (Hall et al. 1994).
Because of the uncertainty regarding the performance of slow sand as a
secondary filtration step and in consideration of the Advisory
Committee recommendation, today's rule establishes a 2.5-log additional
Cryptosporidium treatment credit for this application.
Due to the importance of biological activity to slow sand filter
performance, PWSs may not receive the prescribed treatment credit if
the influent water to the slow sand filter contains a disinfectant
residual. EPA is not establishing design standards for slow sand
filters in today's rule. Studies have shown, however, that design
deficiencies in slow sand filters may lead to poor Cryptosporidium
removal (Fogel et al. 1993). Consequently, States must approve slow
sand filter designs as a secondary filtration stage for PWSs to receive
treatment credit under today's rule.
c. Summary of Major Comments
Public comment on the August 11, 2003 proposal focused on the
question of whether the 2.5-log Cryptosporidium treatment credit for
slow sand as a secondary filtration process is appropriate. Many
commenters supported the proposed treatment credit. These commenters
cited studies demonstrating greater than 4-log Cryptosporidium removal
by slow sand filtration and concluded that the data justify a 2.5-log
treatment credit for slow sand filtration added to a clarification and
filtration treatment train.
Several commenters, however, stated that this treatment credit is
not justified due to the lack of data on the performance of slow sand
as a secondary filtration step. Available studies on slow sand filter
performance for Cryptosporidium removal have mostly been conducted on
raw (i.e., unfiltered) water. These commenters were concerned that if
slow sand filtration is applied following a primary filtration process,
the filter ripening period and other factors will be significantly
affected. As a result, the slow sand filtration may provide only
limited removal over a long ripening period.
In response, EPA recognizes that little testing has been conducted
on the performance of slow sand filtration specifically as a second
filtration stage in a treatment train. However, available data do not
indicate that slow sand filtration would be substantially less
effective when used in this capacity. Slow sand filtration is
recommended only for higher quality source waters, and water quality
following a primary filtration process would be well within recommended
design limits for slow sand filtration (USEPA 1991a). EPA agrees that
filter ripening is critical to slow sand filtration achieving its full
performance level, and this process may require more time when slow
sand filtration follows a primary filtration process. However, this
effect may be counterbalanced by very long filter run times between
cleaning the filter due to the high quality influent water.
Consequently, EPA believes that 2.5-log Cryptosporidium treatment
credit for slow sand as a secondary filtration process is warranted.
14. Ozone and Chlorine Dioxide
a. Today's Rule
PWSs may use ozone and chlorine dioxide to meet Cryptosporidium
treatment requirements under today's rule. To receive treatment credit,
PWSs must measure the water temperature, disinfectant contact time, and
residual disinfectant concentration at least once each day and
determine the log inactivation credit using the tables in this section.
Specific criteria are as follows:
? The temperature of the disinfected water must be measured
at least once per day at each residual disinfectant concentration
sampling point.
? The disinfectant contact time(s) (``t'') must be
determined for each day during peak hourly flow.
? The residual disinfectant concentration(s) (``C'') of the
water before or at the first customer must be measured each day during
peak hourly flow.
? Tables IV.D-3 or IV.D-4 must be used to determine
Cryptosporidium log inactivation credit for ozone or chlorine dioxide,
respectively, based on the water temperature and the product of
disinfectant concentration and contact time (CT).

Table IV.D-3.--CT Values for Cryptosporidium Inactivation by Ozone \1\ (mg/L x min)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water temperature, [deg]C
Log credit -------------------------------------------------------------------------------------------------------------
< =0.5 1 2 3 5 7 10 15 20 25 30
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.25...................................... 6.0 5.8 5.2 4.8 4.0 3.3 2.5 1.6 1.0 0.6 0.39
0.5....................................... 12 12 10 9.5 7.9 6.5 4.9 3.1 2.0 1.2 0.78
1.0....................................... 24 23 21 19 16 13 9.9 6.2 3.9 2.5 1.6
1.5....................................... 36 35 31 29 24 20 15 9.3 5.9 3.7 2.4
2.0....................................... 48 46 42 38 32 26 20 12 7.8 4.9 3.1
2.5....................................... 60 58 52 48 40 33 25 16 9.8 6.2 3.9
3.0....................................... 72 69 63 57 47 39 30 19 12 7.4 4.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ PWSs may use this equation to determine log credit between the indicated values: Log credit = (0.0397 x (1.09757) Temp) x CT.

Table IV.D-4.--CT Values for Cryptosporidium Inactivation by Chlorine Dioxide \1\ (mg/L x min)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water temperature, [deg]C
Log credit -------------------------------------------------------------------------------------------------------------
< =0.5 1 2 3 5 7 10 15 20 25 30
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.25...................................... 159 153 140 128 107 90 69 45 29 19 12
0.5....................................... 319 305 279 256 214 180 138 89 58 38 24
1.0....................................... 637 610 558 511 429 360 277 179 116 75 49
1.5....................................... 956 915 838 767 643 539 415 268 174 113 73
2.0....................................... 1275 1220 1117 1023 858 719 553 357 232 150 98
2.5....................................... 1594 1525 1396 1278 1072 899 691 447 289 188 122
3.0....................................... 1912 1830 1675 1534 1286 1079 830 536 347 226 147
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ PWSs may use this equation to determine log credit between the indicated values: Log credit = (0.001506 x (1.09116) Temp) x CT.

[[Page 708]]

PWSs may have several disinfection segments in sequence along the
treatment train, where a disinfectant segment is defined as a treatment
unit process with a measurable disinfectant residual level and a liquid
volume. In determining the total log inactivation, the PWS may
calculate the CT for each disinfection segment and use the sum of these
values to determine the log inactivation achieved through the plant.
The Toolbox Guidance Manual provides information on recommended
methodologies for determining CT values for different disinfection
reactor designs and operations.
Alternatively, the State may approve alternative CT values to those
specified in Tables IV.D-3 or IV.D-4 based on a site-specific study a
PWSs conducts following a State-approved protocol. The Toolbox Guidance
Manual describes recommended approaches for making such demonstrations.
b. Background and Analysis
Ozone and chlorine dioxide are chemical disinfectants that have
been shown to be effective for inactivating Cryptosporidium. The Stage
2 M-DBP Advisory Committee recommended that EPA develop criteria for
PWSs to achieve Cryptosporidium inactivation credit with these
disinfectants. The August 11, 2003 LT2ESWTR proposal included CT values
for 0.5- to 3-log Cryptosporidium inactivation credit by ozone or
chlorine dioxide at temperatures ranging from less than 0.5 C to 25 C,
along with daily required monitoring (USEPA 2003a). Today's final rule
establishes these criteria with no changes from the proposed rule, but
expands the CT tables down to 0.25-log inactivation and up to a water
temperature of 30 C. The following discussion summarizes the basis for
these criteria.
The requirements for at least daily monitoring of the water
temperature, residual disinfectant concentration, and contact time
during peak hourly flow to determine a daily inactivation level reflect
existing requirements for Giardia inactivation by chemical disinfection
in 40 CFR 141.74. EPA expects that in practice, many PWSs using ozone
or chlorine dioxide will monitor more frequently and for multiple
disinfectant segments. In the Toolbox Guidance Manual, EPA provides
information on recommended approaches for monitoring and calculating CT
values for ozone and chlorine dioxide reactors.
The CT values for both ozone and chlorine dioxide are based on
analyses by Clark et al. (2002a,b), with additional procedures to
assess confidence bounds. Clark et al. (2002a,b) developed predictive
equations for Cryptosporidium inactivation through evaluating studies
on ozone by Rennecker et al. (1999), Li et al. (2001), Owens et al.
(2000), and Oppenheimer et al. (2000) and on chlorine dioxide by Li et
al. (2001), Owens et al. (1999) and Ruffell et al. (2000). EPA applied
confidence bounds to these predictive equations to ensure that PWSs
operating at a given CT value are likely to achieve at least the
corresponding log inactivation level in the CT table.
In identifying confidence bounds for CT values, EPA was primarily
concerned with uncertainty in the estimations by Clark et al. (2002a,b)
of the linear relationship between log inactivation and CT (i.e.,
uncertainty in the regression) and with real variability in the
inactivation rate. Such real variability could be associated with
different populations of oocysts and different water matrices. In
contrast, variability associated with experimental error, such as the
assays used to measure loss of infectivity, was a lessor concern. The
purpose of the CT tables is to ensure a given level of inactivation and
not to predict the measured result of an individual experiment.
For developing earlier CT values, EPA has used bounds for
confidence in prediction, which account for both real variability and
experimental error. EPA believes that this approach was appropriate due
to limited inactivation data and uncertainty in the sources of
variability in the data. However, the high doses of ozone and chlorine
dioxide necessary to inactivate Cryptosporidium create an offsetting
concern with the formation of DBPs (e.g., bromate and chlorite). In
consideration of this concern, EPA has employed a less conservative
method to calculate confidence bounds for the ozone and chlorine
dioxide CT values in today's rule; specifically, EPA has attempted to
exclude experimental error from the confidence bounds.
In order to estimate confidence bounds that exclude experimental
error, EPA assessed the relative contribution of experimental error to
the variance observed in the Cryptosporidium inactivation data sets.
This assessment was done by comparing variance among data points with
consistent experimental conditions, which was attributed to
experimental error, with the total variance in a data set. By this
analysis, EPA estimated that 87.5 and 62 percent of the variance in the
Cryptosporidium inactivation data for ozone and chlorine dioxide,
respectively, could be ascribed to experimental error (Sivaganesan
2003, Messner 2003). EPA then applied these estimates to the predictive
equations developed by Clark et al. (2002a,b) using a modified form of
a formula for calculating a 90 percent confidence bound (Messner 2003).
This analysis produced the CT values shown in tables IV.D-3 and
IV.D-4 for ozone and chlorine dioxide, respectively. CT values are
provided for inactivation as low as 0.25-log. Such a low inactivation
level may be used by PWSs applying ozone in combination with other
disinfectants. Available data do not support the determination of
conditions for inactivation greater than 3-log, so the CT values in
today's rule do not go beyond this level. The temperature range of CT
values in today's rule goes to 30 C (86 F), which will accommodate most
natural waters. If the water temperature is higher than 30 C,
temperature should be set to 30 C for the log inactivation calculation.
PWSs may use the equations provided as footnotes to tables IV.D-3 and
IV.D-4 to interpolate between CT values.
EPA recognizes that inactivation rates may be sensitive to water
quality and operational conditions at individual PWSs. To reflect this
potential, PWSs are allowed to perform a site-specific inactivation
study to determine CT requirements. The State must approve the
protocols or other information used to derive alternative CT values.
EPA has provided guidance for such studies in the Toolbox Guidance Manual.
c. Summary of Major Comments
Public comment on the August 11, 2003 LT2ESWTR proposal supported
the inclusion of ozone and chlorine dioxide in the microbial toolbox
for Cryptosporidium inactivation. Commenters stated concerns with the
required criteria for achieving Cryptosporidium treatment credit,
including the conservatism EPA applied in developing the CT tables, the
ability of PWSs with different types of source waters to use these
disinfectants, and the range of conditions covered by the CT tables.
Commenters also made recommendations for guidance. These comments and
EPA's responses are summarized as follows.
Some commenters supported the proposed CT tables, but others stated
that the statistical approach used to calculate the confidence bounds
from which the CT values are derived is overly conservative. These
commenters were concerned that this approach will increase capital and
operating costs and lead to higher byproduct levels.
In response, EPA believes that the confidence bounds used for the
ozone and chlorine dioxide CT tables in today's rule are appropriate and

[[Page 709]]

necessary to ensure that PWSs achieve intended levels of
Cryptosporidium inactivation. They account only for uncertainty in the
regression of inactivation data and for variability in inactivation
data that cannot be attributed to experimental error. This approach is
significantly less conservative than the approaches used in CT tables
for earlier rules. EPA employed this less conservative approach in
recognition of the high disinfectant doses necessary for
Cryptosporidium inactivation and concern with byproducts.
Commenters were concerned that due to the relatively high ozone and
chlorine dioxide doses necessary for Cryptosporidium inactivation, some
PWSs will be unable to use these disinfectants to achieve required
levels of Cryptosporidium treatment. In particular, using ozone for
high Cryptosporidium inactivation levels will be difficult in areas
where cold water temperatures would necessitate especially high doses
or where high source water bromide levels would cause problems with
bromate formation. The use of chlorine dioxide for Cryptosporidium
inactivation may be difficult due to chlorite formation.
EPA recognizes that the use of ozone and chlorine dioxide to
achieve Cryptosporidium inactivation will depend on source water
factors and will not be feasible for all PWSs. Due to the availability
of UV, which EPA has determined to be a feasible technology for
Cryptosporidium inactivation by all PWS sizes, the feasibility of
today's rule does not depend on the widespread use of ozone or chlorine
dioxide for compliance. In assessing the impact of today's rule on
PWSs, EPA used ICR survey data to estimate the fraction of PWSs that
could use ozone or chlorine dioxide to achieve different levels of
Cryptosporidium inactivation without exceeding DBP MCLs (see Economic
Analysis for the LT2ESWTR). While EPA expects that some PWSs will use
these disinfectants, the microbial toolbox provides many other options
for PWSs to comply with the Cryptosporidium treatment requirements of
today's rule.
Commenters recommended that EPA expand the range of conditions
encompassed in the CT tables. Specifically, commenters asked that CT
tables include values for water temperatures above 25 C and supported
this request by providing data showing temperature profiles for water
sources with maximum temperatures near 30 C. Commenters also requested
CT values for Cryptosporidium inactivation levels below 0.5-log for
PWSs that will use multiple disinfectants to meet the treatment
requirements in today's rule. In addition, commenters suggested that
EPA provide equations that PWSs can use to interpolate between the
listed CT values.
EPA has addressed these recommendations in today's final rule. The
CT tables for ozone and chlorine dioxide include values for a water
temperature of 30 C and for 0.25-log inactivation. Footnotes to these
tables contain equations that PWSs can use to calculate log
inactivation credit for conditions between those provided in the
tables. PWSs may use these equations in their process control systems.
Commenters made recommendations for guidance on the use of ozone
and chlorine dioxide to comply with today's rule. These recommendations
concern topics like monitoring disinfection reactors, procedures for
calculating disinfectant concentration and contact time, site specific
studies, and synergistic effects of multiple disinfectants. EPA has
addressed these topics in the Toolbox Guidance Manual.
15. Ultraviolet Light
a. Today's Rule
PWSs may use ultraviolet (UV) light to comply with Cryptosporidium
treatment requirements in today's rule, as well as Giardia lamblia and
virus treatment requirements in existing regulations. To receive
treatment credit, PWSs must operate UV reactors validated to achieve
the required UV dose, as shown in the table in this section, and
monitor their UV reactors to demonstrate operation within validated
conditions. Specific criteria are as follows:

Required UV Doses

? UV dose (fluence) is the product of the UV intensity over
a surface area (fluence rate) and the exposure time. PWSs must use
validation testing to demonstrate that a UV reactor achieves the UV
doses shown in Table IV.D-5 in order to receive the associated
inactivation credit.

Table IV.D-5.--UV Dose Requirements for Cryptosporidium, Giardia lamblia, and Virus Inactivation Credit
----------------------------------------------------------------------------------------------------------------
Cryptosporidium UV Giardia lamblia UV Virus UV dose (mJ/
Log credit dose (mJ/cm2) dose (mJ/cm2) cm2)
----------------------------------------------------------------------------------------------------------------
0.5......................................... 1.6 1.5 39
1.0......................................... 2.5 2.1 58
1.5......................................... 3.9 3.0 79
2.0......................................... 5.8 5.2 100
2.5......................................... 8.5 7.7 121
3.0......................................... 12 11 143
3.5......................................... 15 15 163
4.0......................................... 22 22 186
----------------------------------------------------------------------------------------------------------------

? The dose values in Table IV.D-5 are for UV light at a
wavelength of 254 nm as delivered by a low pressure mercury vapor lamp.
However, PWSs may use this table to determine treatment credits for
other lamp types through validation testing, as described in the UV
Disinfection Guidance Manual. The dose values in Table IV.D-5 apply to
post-filter applications of UV in filtration plants and to PWSs that
meet all applicable filtration avoidance criteria.

UV Reactor Validation Testing

? The validation test may be reactor-specific or site-
specific. Unless the State approves an alternative approach, this
testing must involve the following: (1) Full scale testing of a reactor
that conforms uniformly to the UV reactors used by the PWS, and (2)
inactivation of a test microorganism whose dose response characteristics
have been quantified with a low pressure mercury vapor lamp.
? Validation testing must identify ranges for parameters the
PWS can monitor to ensure that the required UV dose is delivered during
operation. These parameters must include flow rate, UV intensity as
measured by UV sensors, and UV lamp status.
? The operating parameters determined by validation testing must

[[Page 710]]

account for the following factors: (1) UV absorbance of the water, (2)
lamp fouling and aging, (3) measurement uncertainty of UV sensors, (4)
dose distributions arising from the flow velocity profiles through the
reactor, (5) failure of UV lamps or other critical system components,
and (6) inlet and outlet piping or channel configurations of the UV
reactor. In the UV Disinfection Guidance Manual, EPA describes
recommended approaches for reactor validation that address these factors.

UV Reactor Monitoring

? PWSs must monitor for the parameters necessary to
demonstrate operation within the validated conditions of the required
UV dose. These parameters must include flow rate, UV intensity as
measured by UV sensors, and UV lamp status. PWSs must check the
calibration of UV sensors and recalibrate in accordance with a protocol
approved by the State.
? For PWSs using UV light to meet microbial treatment
requirements, at least 95 percent of the water delivered to the public
every month must be treated by UV reactors operating within validated
conditions for the required UV dose.
b. Background and Analysis
Numerous studies have demonstrated that UV light is effective for
inactivating Cryptosporidium, Giardia lamblia, and other microbial
pathogens at relatively low doses (Clancy et al. 1998, 2000, 2002,
Bukhari et al. 1999, Craik et al. 2000, 2001, Landis et al. 2000,
Sommer et al. 2001, Shin et al. 2001, and Oppenheimer et al. 2002). EPA
has determined that UV light is a feasible technology for PWSs of all
sizes to inactivate Cryptosporidium. Accordingly, EPA expects that UV
is one of the primary technologies PWSs will use to comply with
Cryptosporidium treatment requirements in today's rule.
The Stage 2 M-DBP Advisory Committee recommended that EPA establish
standards for the use of UV to comply with drinking water treatment
requirements. These standards include the UV doses necessary for
different levels of Cryptosporidium, Giardia lamblia, and virus
inactivation and a protocol for validating the disinfection performance
of UV reactors. The Committee also directed EPA to develop a UV
disinfection guidance manual to familiarize States and PWSs with
important design and operational issues for UV installations.
The August 11, 2003 LT2ESWTR proposal included UV doses for PWSs to
achieve treatment credit of up to 3-log for Cryptosporidium and Giardia
lamblia and up to 4-log for viruses, along with associated reactor
validation and monitoring requirements. The proposal also required
unfiltered PWSs using UV to achieve the UV dose for the required level
of Cryptosporidium inactivation in at least 95 percent of the water
delivered to the public every month (USEPA 2003a).
Today's final rule establishes these criteria with no changes from
the proposed rule. However, EPA has expanded the UV dose table to
include 4-log inactivation of Cryptosporidium and Giardia lamblia and
has expanded the 95 percent compliance requirement to include filtered
PWSs and to cover Giardia lamblia and virus inactivation. The following
discussion summarizes the basis for these criteria.
The UV dose values in Table IV.D-5 are based on meta-analyses of UV
inactivation studies with Cryptosporidium parvum, Giardia lamblia,
Giardia muris, and adenovirus (Qian et al. 2004, USEPA 2003a). EPA has
expanded the dose values for Cryptosporidium and Giardia lamblia from
3- to 4-log inactivation because available data support criteria for
this level of treatment. Neither today's rule nor any existing
regulations require PWSs to provide Cryptosporidium inactivation above
this level, so EPA has not expanded the UV dose tables further. While
today's rule requires up to 5.5-log Cryptosporidium treatment by
filtered PWSs, at least 2.0-log of this treatment must be achieved by
physical removal.
The required UV doses for inactivation of viruses are based on the
dose-response of adenovirus because among waterborne pathogenic viruses
that have been studied, it appears to be the most UV resistant. As
summarized in Embrey (1999), adenoviruses have been identified as the
second most important agent of gastroenteritis in children and can
cause significant adverse health effects, including death, in persons
with compromised immune systems. They are associated with fecal
contamination in water and have been implicated in waterborne disease
outbreaks.
EPA used data from studies performed with low pressure mercury
vapor lamps on water with turbidity representative of filtered water to
derive the UV dose values in Table IV.D-5. Studies with low pressure
mercury vapor lamps were selected because they allow the UV dose to be
accurately quantified (see USEPA 2003a for specific studies). The UV
dose values in Table IV.D-5 can be applied to medium pressure mercury
vapor lamps and other lamp types through UV reactor validation testing,
as described in the UV Disinfection Guidance Manual. Due to the
potential for particulate matter to interfere with UV disinfection, the
application of these dose values is limited to post-filtration in
filtered PWSs and to unfiltered PWSs.
Flow-through UV reactors deliver a distribution of doses due to
variations in light intensity and particle flow path through the
reactor. To best account for the dose distribution, the validation test
must use a challenge microorganism to determine the degree of
inactivation achieved by the UV reactor. This level of performance must
then be associated to the UV dose requirements in Table IV.D-5 through
known dose-response relationships for the challenge microorganism and
target pathogen in order to assign disinfection credit to the UV
reactor. States may approve an alternative basis for awarding UV
disinfection credit.
Today's rule requires full-scale testing of UV reactors to validate
the operating conditions under which the reactors can deliver a
required UV dose. EPA believes this testing is necessary due to the
uncertainty associated with predicting reactor disinfection performance
entirely through modeling or through reduced-scale testing. Under
today's rule, EPA intends UV reactor validation testing to be reactor-
specific and not site-specific. This means that once a UV reactor has
been validated for a range of operating conditions, the validation test
results can be applied by all PWSs that will operate within those
conditions without the need for retesting at each individual site.
Validation testing must account for factors that will influence the
dose delivered by UV reactors during routine operation. These factors
include UV absorbance, lamp fouling, lamp aging, the performance of UV
intensity sensors, hydraulic flow path and residence time
distributions, UV lamp failure, and reactor inlet and outlet
hydraulics. The successful outcome of validation testing is the
determination of acceptable operating ranges for parameters the PWSs
can monitor to ensure delivery of the required UV dose during
treatment. The specific parameters will vary depending on the reactor
control strategy. In all cases, however, PWSs must monitor UV intensity
within the reactor as measured by UV sensors, the flow rate, and the
status of lamps. EPA believes that any effective UV reactor control
strategy will involve monitoring for these parameters.
Today's rule requires all PWSs using UV for disinfection compliance
to treat

[[Page 711]]

at least 95 percent of the water distributed to the public each month
with UV reactors operating within validated conditions for the required
UV dose. EPA views this 95 percent limit as a feasible minimum level of
performance for PWSs to achieve, while ensuring the desired level of
health protection is provided. For purposes of design and operation,
PWSs should strive to deliver the required UV dose at all times during
treatment.
EPA developed these requirements and the associated UV Disinfection
Guidance Manual solely for public water systems using UV light to meet
drinking water disinfection standards established under SDWA. EPA has
not addressed and did not consider the extension of these requirements
and guidance to other applications, including point of entry or point
of use devices for residential water treatment that are not operated by
public water systems to meet SDWA disinfection standards.
c. Summary of Major Comments
Public comment on the August 11, 2003 LT2ESWTR proposal supported
the inclusion of UV light in the microbial toolbox for Cryptosporidium
inactivation. EPA received significant comment on the UV dose tables,
the use of adenovirus as the basis for virus UV dose requirements, UV
compliance standards for filtered systems, and safety factors
associated with draft guidance. These comments and EPA's responses are
summarized as follows.
Commenters generally supported the proposed UV dose values for
Cryptosporidium and Giardia lamblia inactivation and recommended that
EPA incorporate these values into the final rule. Several commenters
requested that EPA provide values for 3.5-, 4.0- or higher log
inactivation of Cryptosporidium and Giardia lamblia because available
dose-response data include this range. Due to factors like tailing and
censoring in the underlying dose-response data, some commenters stated
that the proposed UV dose values are conservative and advised EPA to
consider this conservatism when recommending additional safety factors
in guidance.
In response, EPA has extended the UV dose table in today's rule to
cover 3.5- and 4.0-log Cryptosporidium and Giardia lamblia
inactivation. None of EPA's regulations require inactivation of
Cryptosporidium or Giardia lamblia above these levels, so EPA has not
established UV dose requirements for inactivation above 4-log. EPA
believes that the statistical analysis used to determine the required
UV doses appropriately accounts for variability, tailing, and censoring
in the underlying dose-response data. However, the required UV dose
values do not account for bias and uncertainty associated with UV
reactor validation and monitoring, which are addressed in guidance.
Several commenters were concerned with the use of adenovirus to set
UV dose requirements for virus inactivation because the resulting dose
values are several times higher than typical UV doses for drinking
water disinfection. These high dose values impact the feasibility of
PWSs using UV to fully meet virus treatment requirements, which will
hinder the use of UV to reduce DBPs and for point-of-entry treatment.
Commenters requested that EPA consider waterborne viruses that are more
UV-sensitive, such as rotavirus or hepatitus, when setting UV dose
requirements. Commenters noted that adenovirus commonly causes
infections of the lung or eye, which are not transmitted through water
consumption, and that no drinking water outbreaks associated with
adenovirus have been reported in the United States.
EPA recognizes that the UV doses for virus inactivation in today's
rule are relatively high and that this will limit the degree to which
PWSs can use UV for virus treatment. Based on occurrence and health
effects, however, EPA continues to believe that UV dose requirements
should be protective for adenovirus. The existing requirement for 4-log
virus treatment, as established under the SWTR, applies to all
waterborne viruses of public health concern in PWSs. Adenovirus is
consistently found in water subject to fecal contamination and can be
transmitted through consumption of or exposure to contaminated water.
It is a common cause of diarrheal illness, particularly in children,
and fecal shedding is prevalent in asymptomatic adults. While illness
from adenovirus is typically self-limiting, severe health effects,
including death, can occur. Consequently, EPA regards adenovirus as a
potential health concern in PWSs and has established UV dose
requirements to address it.
Many commenters recommended that EPA establish a compliance
standard for the operation of UV reactors within validated conditions
by filtered PWSs, similar to the 95 percent standard proposed for
unfiltered PWSs. Commenters were concerned that without a clear
compliance standard in the rule, filtered PWSs would be held to
inconsistent and unclear standards, which would impede the design and
implementation of UV systems. Some commenters recommended that filtered
PWSs by held to the same 95 percent standard as unfiltered PWSs, while
others recommended a lower 90 percent standard on the basis that
filtered PWSs have more barriers of protection.
EPA agrees that establishing a clear compliance standard for the
use of UV to meet inactivation requirements is appropriate. For
filtered PWSs using UV to meet microbial treatment requirements,
today's final rule requires at least 95 percent of the water
distributed to consumers to be treated by UV reactors operating within
validated conditions. This is the same standard that applies to
unfiltered PWSs. EPA believes that a 95th percentile standard is
feasible for all PWSs and represents the minimum level of performance
that should be achieved. During routine operation, PWSs should endeavor
to maintain UV reactors within validated conditions for the required UV
dose at all times.

E. Disinfection Benchmarking for Giardia lamblia and Viruses

1. Today's Rule
The purpose of disinfection benchmarking under today's rule is to
ensure that PWSs maintain protection against microbial pathogens as
they implement the Stage 2 DBPR and LT2ESWTR. If a PWS proposes to make
a significant change in disinfection practice, the PWS must perform the
following:
? Develop a disinfection profile for Giardia lamblia and
viruses. A disinfection profile consists of documenting Giardia lamblia
and virus log inactivation levels at least weekly over a period of at
least one year. PWSs that operate for less than one year must profile
only during the period of operation. The calculated log inactivation
levels must include the entire treatment plant and must be based on
operational and water quality data, such as disinfectant residual
concentration(s), contact time(s), temperature(s), and, where
necessary, pH. PWSs may create profiles by conducting new weekly (or
more frequent) monitoring and/or by using previously collected data. A
PWS that created a Giardia lamblia disinfection profile under the
IESWTR or LT1ESWTR may use the operational data collected for the
Giardia lamblia profile to create a virus disinfection profile.
? Calculate a disinfection benchmark, using the following
procedure: (1) Determine the calendar month with the lowest log
inactivation; (2) The lowest month becomes the critical period for that
year; (3) If acceptable data from

[[Page 712]]

multiple years are available, the average of critical periods for each
year becomes the benchmark; (4) If only one year of data is available,
the critical period for that year is the benchmark.
? Notify the State before implementing the significant
change in disinfection practice. The notification to the State must
include a description of the proposed change, the disinfection profiles
and inactivation benchmarks for Giardia lamblia and viruses, and an
analysis of how the proposed change will affect the current
inactivation benchmarks.
For the purpose of these requirements, significant changes in
disinfection practice are defined as (1) moving the point of
disinfection (this is not intended to include routine seasonal changes
already approved by the State), (2) changing the type of disinfectant,
(3) changing the disinfection process, or (4) making other
modifications designated as significant by the State. The Disinfection
Profiling and Benchmarking Guidance Manual provides information to PWSs
and States on the development of disinfection profiles, identification
and evaluation of significant changes in disinfection practices, and
considerations for setting an alternative benchmark (USEPA 1999d).
2. Background and Analysis
A goal in the development of rules to control microbial pathogens
and disinfection byproducts (DBPs) is the balancing risks between these
two classes of contaminants. EPA established disinfection profiling and
benchmarking under the IESWTR and LT1ESWTR, based on a recommendation
by the Stage 1 M-DBP Advisory Committee, to ensure that PWSs maintained
adequate protection against pathogens as they reduced risk from DBPs.
EPA is extending profiling and benchmarking requirements to the
LT2ESWTR for the same objective.
Some PWSs will make significant changes in their current
disinfection practice to meet TTHM and HAA5 requirements under the
Stage 2 DBPR and to provide additional treatment for Cryptosporidium
under the LT2ESWTR. To ensure that these PWSs maintain disinfection
that is effective against a broad spectrum of microbial pathogens, EPA
believes that PWSs and States should evaluate the effects of
significant changes in disinfection practice on current microbial
treatment levels. Disinfection profiling and benchmarking serves as a
tool for making such evaluations.
The August 11, 2003 LT2ESWTR proposal included disinfection
profiling and benchmarking requirements. Under the proposal, profiling
for Giardia lamblia and viruses was required if a PWS was required to
monitor for Cryptosporidium or, in the case of small PWSs, exceeded 80
percent of the TTHM or HAA5 MCL based on a locational running annual
average. Under this approach, most large PWSs and a significant
fraction of small PWSs were required to develop profiles. The proposal
also included a schedule for disinfection profile development. Those
PWSs that developed profiles were then required to calculate a
disinfection benchmark and notify the State if they proposed to make a
significant change in disinfection practice.
In today's final rule, EPA has significantly modified the
applicability requirements for disinfection profiling. PWSs are only
required to develop a disinfection profile if they propose to make a
significant change in disinfection practice after completing the first
round of source water monitoring. EPA has made this change from the
proposal because under the LT2ESWTR and Stage 2 DBPR, most PWSs will
not be required to make significant changes to their disinfection
practice. Consequently, most PWSs will not need a disinfection profile.
EPA believes that disinfection profiling requirements should be
targeted to those PWSs that will make significant disinfection changes.
EPA has also eliminated the scheduling requirements for development
of the disinfection profile in order to provide more flexibility to
PWSs and States. Today's rule only requires that PWSs notify States
prior to making a significant change in their disinfection practice and
that this notification include the disinfection profiles and
benchmarks, along with an analysis of how the proposed change will
affect the current benchmarks. EPA believes that PWSs should collect
the operational data needed to develop disinfection profiles, such as
disinfectant residual, water temperature, and flow rate, as part of
routine practice. PWSs that do not have current disinfection profiles
should record this operational information at least weekly for one year
so that they can use it to develop disinfection profiles if required.
Today's rule retains the proposed requirement that when
disinfection profiling is required, PWSs must develop profiles for both
Giardia lamblia and viruses. EPA believes that profiling for both
target pathogens is appropriate because the types of treatment changes
that PWSs will make to comply with the Stage 2 DBPR or LT2ESWTR could
lead to a significant change in the inactivation level for one pathogen
but not the other. For example, a PWS that switches from chlorine to UV
light to meet Giardia lamblia inactivation requirements is likely to
maintain a high level of treatment for this pathogen. The level of
treatment for viruses, however, may be significantly reduced. In
general, viruses are much more sensitive to chlorine than Giardia but
are more resistant to UV. The situation for a PWS switching to
microfiltration is similar. The same operational data are used to
develop disinfection profiles for both Giardia lamblia and viruses.
As was the case with the IESWTR and LT1ESWTR, the disinfection
benchmark under today's rule is not intended to function as a
regulatory standard. Rather, the objective of these provisions is to
facilitate interactions between the States and PWSs to assess the
impact on microbial risk of proposed changes to disinfection practice.
Final decisions regarding levels of disinfection for Giardia lamblia
and viruses beyond the minimum required by regulation will continue to
be left to the States and PWSs. To ensure that the level of treatment
for both protozoan and viral pathogens is appropriate, States and PWSs
should consider site-specific factors such as source water
contamination levels and the reliability of treatment processes.
3. Summary of Major Comments
EPA received significant public comment on disinfection profiling
and benchmarking requirements in the August 11, 2003 proposal. A few
commenters supported the proposed requirements but most raised concerns
with the burden and usefulness of disinfection profiling and requested
greater flexibility. These comments and EPA's responses are summarized
as follows.
Commenters stated that disinfection profiling diverts PWS and State
resources from other public health protection activities and presents
an incomplete picture of the information that should be considered when
evaluating disinfection changes. Further, some States can only require
the level of treatment specified in regulations (e.g., the SWTR,
IESWTR, LT1ESWTR) and cannot use a disinfection benchmark to enforce a
higher treatment standard. Some commenters also disagreed with
requiring a disinfection profile for viruses, since current
disinfection practices targeting Giardia lamblia typically achieve much
greater virus inactivation than required.

[[Page 713]]

To address these concerns, commenters requested that profiling only
be required for PWSs prior to switching disinfectants or that States be
allowed to grant waivers from disinfection profiling requirements.
Commenters also recommended that States be given flexibility to
determine the appropriate time for PWSs to develop disinfection
profiles, if necessary. In regard to virus profiling, some commenters
suggested that it only be required for PWSs that have not developed
profiles for Giardia lamblia or that are switching disinfectants to UV.
In response, EPA has modified the proposed requirements for
disinfection profiling and benchmarking from the proposal to
significantly reduce the burden on PWSs and States. In today's final
rule, profiling is only required for PWSs that propose to make a
significant change in disinfection practice. EPA projects that most
PWSs will not be required to make treatment changes to comply with the
LT2ESWTR and Stage 2 DBPR and, as a result, will not be required to
develop disinfection profiles. Further, today's rule gives PWSs and
States flexibility to determine the timing for developing disinfection
profiles and only requires that the profiles and benchmarks be included
in a notification to the State before a PWS implements a significant
change in disinfection practice. For PWSs that have not developed
disinfection profiles, EPA recommends recording the necessary
operational data at least weekly over one year so that a profile can be
prepared if needed.
For PWSs that propose to make a significant change in disinfection
practice, today's rule maintains the proposed requirement for a
disinfection profile for viruses. EPA recognizes that current
disinfection practices with chlorine typically achieve far more virus
inactivation than required. However, the types of treatment changes
that PWSs will make to comply with the Stage 2 DBPR or LT2ESWTR, such
as implementing UV or microfiltration, are likely to maintain high
levels of treatment for Giardia lamblia but may result in a significant
decrease in treatment for viruses. Consequently, EPA believes that
States and PWSs should consider whether such a decrease in virus
treatment will occur when evaluating proposed treatment changes.
Moreover, developing a virus disinfection profile does not require
the collection of operational data beyond that necessary to develop a
Giardia lamblia disinfection profile. Therefore, today's rule allows
PWSs to use previously developed Giardia lamblia disinfection profiles
and allows the operational data that underlie the Giardia lamblia
profile to be used for a virus disinfection profile.

F. Requirements for Systems With Uncovered Finished Water Storage Facilities

1. Today's Rule
Today's rule requires PWSs that store treated water in an open
reservoir (i.e., use uncovered finished water storage facilities) to do
either of the following:
? Cover the finished water storage facility; or
? Treat the discharge of the uncovered finished water
storage facility that is distributed to consumers to achieve
inactivation and/or removal of 4-log virus, 3-log Giardia lamblia, and
2-log Cryptosporidium.
PWSs must notify the State if they use uncovered finished water
storage facilities no later than April 1, 2008. PWSs must either meet
the requirements of today's rule for covering or treating each facility
or be in compliance with a State-approved schedule for meeting these
requirements no later than April 1, 2009.
Today's rule revises the definition of an uncovered finished water
storage facility as follows: uncovered finished water storage facility
is a tank, reservoir, or other facility used to store water that will
undergo no further treatment to reduce microbial pathogens except
residual disinfection and is directly open to the atmosphere.
2. Background and Analysis
The requirements in today's rule for PWSs that use uncovered
finished water storage facilities (open reservoirs) are based on an
assessment of the types and sources of contaminants in open reservoirs,
the efficacy and feasibility of regulatory approaches to reduce risks
from this contamination, and comments on the August 11, 2003 proposal.
The following discussion summarizes this assessment.
a. Types and sources of contaminants in open reservoirs. The
storage of treated drinking water in open reservoirs can lead to
significant water quality degradation and health risks to consumers
(USEPA 1999e). Examples of such water quality degradation include
increases in algal cells, coliform bacteria, heterotrophic plate count
bacteria, turbidity, particulates, DBPs, metals, taste and odor, insect
larvae, Giardia, Cryptosporidium, and nitrate (USEPA 1999e).
Contamination of open reservoirs occurs through surface water runoff,
bird and animal wastes, human activity, algal growth, insects and fish,
and airborne deposition. Additional information on these sources of
contamination follows.
If a reservoir receives surface water runoff, the SWTR requires
that it be treated as raw water storage, rather than a finished water
reservoir (40 CFR 141.70(a)). Nevertheless, many uncovered finished
water reservoirs have been found to be affected by surface water
runoff, which may include agricultural fertilizers, pesticides,
microbial pathogens, automotive fluids and residues, sediment,
nutrients, natural organic matter, and metals (USEPA 1999e,
LeChevallier et al. 1997).
Birds are a significant cause of contamination in open reservoirs,
and bird feces may contain coliform bacteria, viruses, and other human
pathogens, including vibrio cholera, Salmonella, Mycobacteria, Typhoid,
Giardia, and Cryptosporidium (Geldreich and Shaw 1993). Birds can
ingest pathogens at landfills or wastewater treatment plants prior to
visiting a reservoir and have been shown to carry and pass infectious
Cryptosporidium parvum (Graczyk et al. 1996). Five to twenty percent of
birds are estimated to be periodically infected with human pathogens
like Salmonella (USEPA 1999e). A 1993 Salmonella outbreak in Gideon, MO
that resulted in seven deaths was traced to pigeons roosting in a
finished water storage tank.
Animals that are either known or suspected to contaminate open
reservoirs include dogs, cats, deer, rats, mice, opossums, squirrels,
muskrats, raccoons, beavers, rabbits, and frogs. Some animals are
infected with human pathogens like Cryptosporidium, which can be
discharged to the reservoirs in feces or transmitted by direct contact
between animals and the water (Fayer and Unger 1986, Current 1986,
USEPA 1999e).
Open reservoirs are exposed to contamination through human
activities. Pesticides and fertilizers can enter open reservoirs
through runoff and airborne drifts from spray applications. Swimming in
reservoirs can result in pathogens being passed from the feces, shedded
skin, and mucus membranes of infected persons. PWSs routinely find a
great variety of items that have been thrown into open reservoirs,
despite the use of high fences and set-back distances. Such items
include baby carriages, beer bottles, bicycles, bullets, dead animals,
dog waste bags, fireworks, garbage cans, a pay phone, shoes, and
shovels (USEPA 1999e). These items are a potential source of pathogens
and toxic substances and clearly indicate the

[[Page 714]]

susceptibility of open reservoirs to intentional contamination.
Algal growth is common in open reservoirs and can lead to aesthetic
problems like color, taste, and odor, and may generate cyanobacterial
toxins, which cause headaches, fever, diarrhea, abdominal pain, nausea,
and vomiting. In addition, algae can increase other contaminants like
DBPs by increasing biomass within reservoirs, and corrosion products
like lead, through causing significant pH fluctuations. Algae have been
shown to shield bacteria from the effects of disinfection (Geldreich
and Shaw 1993).
Open reservoirs may be infested with the larvae of insects such as
midge flies, water fleas, and gnats, which can be carried through the
distribution system from the reservoir (USEPA 1999e). Chlorination is
ineffective against midge fly larvae. Fly outbreaks may increase the
presence of insect-eating birds, which present another source of
contamination as described earlier. Some open finished water reservoirs
have been found to support fish populations.
Open reservoirs also are subject to airborne deposition of
contaminants, such as industrial pollutants, automobile emissions,
pollen, dust, particulate matter, and bacteria. Deposition occurs
during all types of weather conditions, but is likely to be accelerated
during precipitation events as air pollutants are transported from the
air column above the reservoir by rain or snow.
b. Regulatory approaches to reduce risk from contamination in open
reservoirs. For many decades, public health agencies and professional
associations like the American Public Health Association, the U.S.
Public Health Service, and the American Water Works Association have
recommended that all finished water reservoirs be covered (USEPA
1999e). In the IESWTR and LT1ESWTR, EPA prohibited the construction of
new uncovered finished water reservoirs (40 CFR 141.170(c) and
141.511). These regulations did not address existing uncovered finished
water reservoirs, however. In the preamble to the IESWTR, EPA stated
that a requirement to cover existing reservoirs would be considered
when data to develop national cost estimates were available.
EPA has now collected the necessary data to estimate costs
associated with regulatory control strategies for uncovered finished
water reservoirs. The August 11, 2003 LT2ESWTR proposal included three
options for PWSs with uncovered finished water reservoirs to reduce
risk: (1) cover the reservoir, (2) treat the discharge to achieve 4-log
virus inactivation, or (3) implement a State-approved risk mitigation
plan (USEPA 2003a). These options reflected recommendations from the
Stage 2 M-DBP Advisory Committee (USEPA 2000a). Today's final rule
includes the first option to cover, modifies the second option to also
require 3-log Giardia and 2-log Cryptosporidium treatment, and does not
establish an option for a risk mitigation plan. The following
discussion describes the basis for these changes.
As described earlier, studies have shown that small mammals and
birds that live near water may be infected with Cryptosporidium and
Giardia and may shed infectious oocysts and cysts into the water
(Graczyk et al. 1996, Fayer and Unger 1986, Current 1986). LeChevallier
et al. (1997) evaluated Cryptosporidium and Giardia levels in six
uncovered finished water reservoirs. The geometric mean concentration
of Cryptosporidium was 1.2 oocysts/100 L in the inlet samples and 8.1
oocysts/100 L in the effluent samples (i.e., 600 percent increase in
the reservoir). For Giardia, the geometric mean concentrations in the
inlet and effluent samples were 1.9 and 6.1 cysts/100 L, respectively
(i.e., 200 percent increase in reservoir).
Most, if not all, PWSs would treat to achieve 4-log virus
inactivation with chlorine. Based on EPA guidance, the dose of chlorine
necessary for 4-log virus inactivation would not achieve even 0.5-log
Giardia inactivation and would produce no inactivation of
Cryptosporidium (USEPA 1991b). Consequently, PWSs treating for viruses
in open reservoirs, as proposed, would provide very little protection
against contamination by Giardia and Cryptosporidium.
Due to the demonstrated potential for contamination by Giardia and
Cryptosporidium in open reservoirs and the ineffectiveness of virus
treatment against these pathogens, today's rule requires PWSs to treat
for Giardia and Cryptosporidium in addition to viruses if they do not
cover their finished water reservoirs. Specifically, today's rule
specifies the same baseline treatment as required for a raw unfiltered
source, which is 4-log virus, 3-log Giardia, and 2-log Cryptosporidium
reduction.
EPA believes that requiring treatment for viruses, Giardia, and
Cryptosporidium in uncovered finished water reservoirs is consistent
with SDWA section 1412(b)(7)(A), which authorizes the use of a
treatment technique to prevent adverse health effects to the extent
feasible if measuring the contaminant is not feasible. Monitoring for
these pathogens at the very low levels that would cause public health
concern and at the frequency necessary to detect contamination events
is not feasible with available analytical methods. EPA has determined
that with the availability of technologies like UV, treating for
Giardia, Cryptosporidium, and viruses is feasible for all PWS sizes.
Today's rule does not allow PWSs to implement a risk mitigation
plan as an alternative to covering a reservoir or treating the
discharge because EPA does not believe that a risk mitigation plan
would provide equivalent public health protection. Consequently, a risk
mitigation plan would not meet the statutory provision for a treatment
technique to prevent adverse health effects from pathogens like Giardia
and Cryptosporidium to the extent feasible (SDWA section 1412(b)(7)(A)).
As discussed earlier, open reservoirs are subject to contamination
from many sources, including runoff, birds, animals, humans, algae,
insects, and airborne deposition. Control measures can provide a degree
of protection against some of these sources (e.g., bird deterrent
wires, security fences with setback distances). All PWSs are
significantly constrained, however, in the degree to which they can
implement such measures with existing open reservoirs due to factors
like the size of the reservoir, the location of the reservoir (e.g.,
within residential communities or parks), and the existing
infrastructure. For example, many open finished water reservoirs are
impacted by runoff, despite the fact that this has been prohibited for
many years under existing regulations (USEPA 1999e). EPA has concluded
that implementing control measures that would be highly effective
against all sources of contamination of open reservoirs would not be
feasible for PWSs. Accordingly, today's rule does not allow this option.
c. Definition of uncovered finished water storage facility. The
IESWTR established the following definition for an uncovered finished
water storage facility: uncovered finished water storage facility is a
tank, reservoir, or other facility used to store water that will
undergo no further treatment except residual disinfection and is open
to the atmosphere.
In the August 11, 2003, proposed LT2ESWTR, EPA requested comment on
whether this definition should be revised. EPA was concerned that it
would not include certain cases in which water is stored in an open
reservoir after a PWS completes treatment to reduce microbial

[[Page 715]]

pathogens. Such a case would be a PWS that applies a corrosion
inhibitor to the effluent of an open reservoir where water is stored
after filtration and primary disinfection. In this case, the PWS could
claim that the corrosion inhibitor constitutes additional treatment
and, consequently, the open reservoir does not meet EPA's definition of
an uncovered finished water storage facility. However, the water stored
in the open reservoir would be subject to microbial contamination from
the sources described in this section and would undergo no further
treatment for this contamination.
Today's rule revises the definition of an uncovered finished water
storage facility in two ways: (1) The phrase ``to reduce microbial
pathogens'' is inserted following the word ``treatment;'' and (2) the
word ``directly'' is inserted prior to ``open to the atmosphere.'' The
first change ensures that an open reservoir where water is stored after
a PWS has completed filtration (where required) and primary
disinfection will be appropriately classified as an uncovered finished
water storage facility. Whether a PWS applies corrosion control or
other treatment to maintain water quality in the distribution system
will not affect this determination.
The second change clarifies that covered reservoirs with air vents
or overflow lines are not uncovered finished water storage facilities.
Such air vents and overflow lines are open to the atmosphere but are
usually hooded or screened to prevent contamination of the water.
Consequently, these reservoirs are not directly open to the atmosphere
and are not subject to the requirements of today's rule for uncovered
finished water storage facilities.
3. Summary of Major Comments
EPA received significant public comment on requirements for
uncovered finished water storage facilities in the August 11, 2003
proposal. Major issues raised by commenters include whether to require
all reservoirs to be covered, requiring treatment for Giardia and
Cryptosporidium, support for the proposed options, and revising the
definition of an uncovered finished water storage facilities. A summary
of these comments and EPA's responses follows.
Several commenters recommended that EPA require all finished water
reservoirs to be covered. These commenters stated that making an
uncovered reservoir equal in quality to a covered reservoir is not
possible--open reservoirs will always be contaminated by fecal material
from birds and small mammals, as well as increased DBPs due to algae
and other aquatic organisms, airborne contaminants, and sediment
stirred up by wind. Commenters were also concerned that uncovered
reservoirs are a major vulnerability for PWS security (i.e.,
intentional contamination). Some commenters cited the fact that there
are hundreds of thousands of covered finished water reservoirs in
comparison to approximately 100 uncovered finished water reservoirs as
evidence that the public health risks of open reservoirs are widely
recognized.
EPA agrees that storing treated water in open reservoirs presents a
risk to public health. With today's final rule, EPA expects that many
PWSs will cover or eliminate uncovered finished water reservoirs. For
reservoirs where covering is not feasible, EPA believes that treating
the water for Giardia, Cryptosporidium, and viruses will provide protection
against the range of pathogens likely to contaminate the reservoir.
Many commenters supported requiring treatment for Giardia and
Cryptosporidium for PWSs that treat the reservoir discharge. Commenters
stated that reservoirs should either be covered or treated as
unfiltered sources (meaning 3-log Giardia, 2-log Cryptosporidium, and
4-log virus treatment). The LeChevallier et al. (1997) study was cited
as demonstrating increases in Giardia and Cryptosporidium in uncovered
finished water reservoirs, and commenters noted that treatment for
viruses would not be effective against these protozoa. EPA agrees with
these comments and today's rule requires treatment for Giardia and
Cryptosporidium, as well as viruses, by PWSs that do not cover their
reservoirs.
Some commenters expressed support for the proposed options,
including allowing risk mitigation plans as an adequate remedy for an
uncovered reservoir. These commenters characterized the proposal as
providing reasonable alternatives to the substantial costs involved in
covering reservoirs or providing alternative storage. Commenters stated
that strategies included in a risk management plan could address the
range of microorganisms for which treatment is necessary, depending on
site-specific circumstances.
EPA recognizes that covering or finding alternative storage for
uncovered finished water reservoirs can be costly. While EPA believes
that covering finished water reservoirs is the most effective approach
to protecting public health, today's rule allows PWSs to provide
treatment for Giardia, Cryptosporidium, and viruses as a feasible
alternative. As described earlier, EPA does not believe that providing
treatment only for viruses, as proposed, would be protective against
the range of pathogens that contaminate open reservoirs. Further, EPA
has concluded that implementing a risk mitigation plan that would
provide equivalent protection to covering or treating a reservoir is
not feasible. This is due to the many potential sources of
contamination and the significant limitations that all PWSs have in the
control measures they can implement for existing open reservoirs.
Commenters supported revising the definition of uncovered finished
water storage facilities to include situations where PWSs apply a
treatment like corrosion control to water stored in an open reservoir
after the water has undergone filtration, where required, and primary
disinfection. In addition, commenters recommended that EPA clarify that
``open to the atmosphere'' in the definition does not include vents and
overflow lines in covered reservoirs. EPA agrees with these comments
and today's rule is consistent with them.

G. Compliance Schedules

1. Today's Rule
This section specifies compliance dates for the monitoring and
treatment technique requirements in today's rule. As described in
sections IV.A through IV.F of this preamble, today's rule requires PWSs
to carry out the following activities:
? Conduct initial source water monitoring on a reported
schedule. PWSs may grandfather previously collected monitoring results
and may elect to provide the maximum Cryptosporidium treatment level of
5.5-log for filtered PWSs or 3.0-log for unfiltered PWSs instead of
monitoring.
? Determine a treatment bin classification (or mean
Cryptosporidium level for unfiltered PWSs) based on monitoring results.
? For filtered PWSs in Bins 2-4 and all unfiltered PWSs,
provide additional treatment for Cryptosporidium by selecting
technologies from the microbial toolbox.
? Report disinfection profiles and benchmarks prior to
making a significant change in disinfection practice.
? Report the use of uncovered finished water storage
facilities and cover or treat the discharge of such reservoirs on a
State-approved schedule.

[[Page 716]]

? Conduct a second round of source water monitoring
approximately six years after initial bin classification.
Compliance dates for these activities vary by PWS size. Tables
IV.G-1 and IV.G-2 specify source water monitoring and treatment
compliance dates for large and small PWSs, respectively. Table IV.G-3
shows compliance dates for PWSs using uncovered finished water storage
facilities. Wholesale PWSs must comply with the requirements of today's
rule based on the population of the largest PWS in the combined
distribution system.

Table IV.G-1.--Monitoring and Treatment Compliance Dates for PWSs Serving at Least 10,000 People
----------------------------------------------------------------------------------------------------------------
Compliance dates by PWS Size
--------------------------------------------------------------------------
Requirement PWSs serving at least PWSs serving at least
PWSs serving at least 50,000 but less than 10,000 but less than
100,000 people 100,000 people 50,000 people
----------------------------------------------------------------------------------------------------------------
Report sampling schedule and sampling No later than July 1, No later than January No later than January
location description for initial 2006.. 1, 2007. 1, 2008.
source water monitoring for
Cryptosporidium (plus E. coli and
turbidity at filtered PWSs) 1, 2.
Report notice of intent to
grandfather previously collected
Cryptosporidium data, if applicable.
Report intent to provide the maximum
Cryptosporidium treatment level in
lieu of monitoring, if applicable
\1\.
Begin initial source water monitoring No later than the month No later than the month No later than the month
for Cryptosporidium (plus E. coli beginning October 1, beginning April 1, beginning April 1,
and turbidity at filtered PWSs) 1,2. 2006. 2007. 2008.
Submit previously collected No later than December No later than June 1, No later than June 1,
Cryptosporidium data and required 1, 2006. 2007.. 2008.
documentation for grandfathering, if
applicable.
Report Cryptosporidium treatment bin No later than the month No later than the month No later than the month
classification (or mean beginning April 1, beginning October 1, beginning October 1,
Cryptosporidium concentration for 2009. 2009. 2010.
unfiltered PWSs) and supporting data
for approval.
Report disinfection profiles and Prior to making a significant change in disinfection practice.
benchmarks, if applicable.
Comply with additional No later than April 1, No later than October No later than October
Cryptosporidium treatment 2012 \3\. 1, 2013 \3\. 1, 2012 \3\.
requirements based on treatment bin
classification (or mean
Cryptosporidium concentration for
unfiltered PWSs) \3\.
Report sampling schedule and sampling No later than January No later than July 1, No later than July 1,
location description for second 1, 2015. 2015.. 2016.
round of source water monitoring for
Cryptosporidium (plus E. coli and
turbidity at filtered PWSs) \1\.
Report intent to provide maximum
Cryptosporidium treatment level in
lieu of monitoring, if applicable
\1\.
Begin second round of source water No later than the month No later than the month No later than the month
monitoring for Cryptosporidium (plus beginning April 1, beginning October 1, beginning October 1,
E. coli and turbidity at filtered 2015. 2015. 2016.
PWSs) \1\.
Report Cryptosporidium treatment bin No later than the month No later than the month No later than the month
classification (or mean beginning October 1, beginning April 1, beginning April 1,
Cryptosporidium concentration for 2017. 2018. 2019.
unfiltered PWSs) and supporting data
from second round of monitoring for
approval.
Comply with additional On a schedule the State approves.
Cryptosporidium treatment
requirements if bin classification
(or mean Cryptosporidium
concentration for unfiltered PWSs)
changes based on second round of
monitoring.
----------------------------------------------------------------------------------------------------------------
\1\ PWS are not required to conduct source water monitoring if they submit a notice of intent to provide the
maximum Cryptosporidium treatment level: 5.5-log for filtered PWSs or 3.0-log for unfiltered PWSs.
\2\ Not required if PWS grandfathers at least 2 years of Cryptosporidium data.
\3\ States may grant up to an additional 2 years for systems making capital improvements.

Table IV.G-2.--Monitoring and Treatment Compliance Dates for PWSs
Serving Fewer Than 10,000 People
------------------------------------------------------------------------
Requirement Compliance dates
------------------------------------------------------------------------
Indicator (E. coli) Monitoring Requirements for Filtered PWSs Only
------------------------------------------------------------------------
Report sampling schedule and sampling No later than July 1, 2008.
location description for initial
source water monitoring for E. coli or
alternative State-approved indicator1
2.
Report notice intent to grandfather ...............................
previously collected E. coli data, if
applicable.
Report intent to provide the maximum ...............................
Cryptosporidium treatment level in
lieu of monitoring, if applicable \1\.
Begin initial source water monitoring No later than the month
for E. coli1 2. beginning October 1, 2008.
Report E. coli data for grandfathering, No later than December 1, 2008.
if applicable.

[[Page 717]]

Report sampling schedule and sampling No later than July 1, 2017.
location description for second round
of source water monitoring for E. coli
\1\.
Report intent to provide the maximum ...............................
Cryptosporidium treatment level in
lieu of monitoring, if applicable \1\.
Begin second round of source water No later than the month
monitoring for E. coli \1\. beginning October 1, 2017.
------------------------------------------------------------------------

Compliance dates by monitoring option
---------------------------------------
Requirement PWSs monitoring PWSs monitoring
twice-per-month monthly for 2
for 1 year years
------------------------------------------------------------------------
Cryptosporidium Monitoring Requirements for Filtered PWSs That Exceed
Indicator (E. coli) Trigger Concentration \3\ and All Unfiltered PWSs
------------------------------------------------------------------------
Report sampling schedule and No later than January 1, 2010.
sampling location description
(if not reported previously)
for initial source water
monitoring for Cryptosporidium
1 4.
Report notice of intent to
grandfather previously
collected Cryptosporidium data,
if applicable.
Begin initial source water No later than the month beginning
monitoring for Cryptosporidium April 1, 2010.
1 4.
Submit previously collected No later than June
Cryptosporidium data and 1, 2010.
required documentation for
grandfathering, if applicable.
Report Cryptosporidium treatment No later than the No later than the
bin classification (or mean month beginning month beginning
Cryptosporidium concentration October 1, 2011. October 1, 2012.
for unfiltered PWSs) and
supporting data for approval.
Report disinfection profiles and Prior to making a significant change
benchmarks, if applicable. in disinfection practice.
Comply with additional No later than
Cryptosporidium treatment October 1, 2014
requirements based on treatment \5\.
bin classification (or mean
Cryptosporidium concentration
for unfiltered PWSs) \5\.
Report sampling schedule No later than than
sampling location description January 1, 2019.
(if not reported previously)
for second round of source
water Cryptosporidium
monitoring \1\.
Begin second round of source No later than the
water monitoring for month beginning
Cryptosporidium \1\.. April 1, 2019.
Report Cryptosporidium treatment No later than the No later than the
bin classification (or mean month beginning month beginning
Cryptosporidium concentration October 1, 2020. October 1, 2021.
for unfiltered PWSs) and
supporting data from second
round of monitoring for
approval.
Comply with additional On a schedule the State approves.
Cryptosporidium treatment
requirements if bin
classification (or mean
Cryptosporidium concentration
for unfiltered PWSs) changes
based on second round of
monitoring.
------------------------------------------------------------------------
\1\ PWS are not required to conduct source water monitoring if they
submit a notice of intent to provide the maximum Cryptosporidium
treatment level: 5.5-log for filtered PWSs or 3.0-log for unfiltered
PWSs.
\2\ Not required if PWS grandfathers at least 1 year of E. coli data.
\3\ Filtered PWSs must conduct Cryptosporidium monitoring if the E. coli
annual mean concentration exceeds 10/100 mL for PWSs using lake or
reservoir sources or exceeds 50/100 mL for PWSs using flowing stream
sources or a trigger value for an alternative State-approved indicator
is exceeded.
\4\ Not required if PWS grandfathers at least 1 year of twice-per-month
or 2 years of monthly Cryptosporidium data.
\5\ States may grant up to an additional 2 years for PWSs making capital
improvements.

Table IV.G-3.--Compliance Dates for PWSs Using Uncovered Finished Water
Storage Facilities
------------------------------------------------------------------------

------------------------------------------------------------------------
Report the use of uncovered finished No later than April 1, 2008.
water storage facilities, if
applicable.
Either comply with requirement to cover No later than April 1, 2009.
or treat uncovered finished water
storage facilities or comply with
State-approved schedule to meet this
requirement.
------------------------------------------------------------------------

2. Background and Analysis
The compliance schedule in today's final rule stems from its risk-
targeted approach, wherein PWSs initially conduct monitoring to
determine additional treatment requirements. A primary objective of
this schedule is to ensure that PWSs provide additional treatment
without delay for higher risk sources. This is especially important
with a risk-targeted rule, given the significant time required for
initial monitoring. However, the compliance schedule balances this
objective with the need to provide PWSs and States with time to prepare
for implementation activities.
SDWA section 1412(b)(10) states that a drinking water regulation
shall take effect 3 years from the promulgation date unless the
Administrator determines that an earlier date is practicable. Today's
rule requires PWSs to begin monitoring prior to 3 years from the
promulgation date. Based on EPA's assessment and recommendations of the
Advisory Committee, as described in this section, EPA has determined
that these monitoring start dates are practicable and appropriate.

[[Page 718]]

In general, PWSs serving at least 10,000 people conduct two years
of source water monitoring for Cryptosporidium (as well as E. coli and
turbidity in filtered PWSs). At the conclusion of this monitoring,
these PWSs have six months to analyze monitoring results and report
their treatment bin classification to the State for approval. Where
required, PWSs must provide the necessary level of additional
Cryptosporidium treatment within three years of bin classification,
though States may allow an additional two years for PWSs making capital
improvements. A second round of source water monitoring must be
initiated six years after initial bin classification.
For PWSs serving at least 10,000 people, the timing of monitoring
and treatment activities in today's rule partially reflects
recommendations by the Stage 2 M-DBP Advisory Committee and the
schedule in the August 11, 2003 proposed LT2ESWTR. EPA has modified the
proposed compliance schedule to stagger monitoring start dates for PWSs
serving 10,000 to 99,999 people. The following discussion addresses
these changes from the proposal.
The proposed rule required all PWSs serving at least 10,000 people
to begin source water monitoring six months after the rule was
established, as recommended by the Advisory Committee. Under today's
final rule, PWSs serving at least 100,000 people maintain this
schedule. The monitoring start date for PWSs serving 50,000 to 99,999
people is staggered by six months and begins 12 months after the rule
is effective. For PWSs serving 10,000 to 49,999, the monitoring start
date is staggered by 18 months and begins 24 months after the rule is
effective. Dates to comply with additional treatment requirements are
staggered accordingly.
This staggering of monitoring start dates for PWSs serving 10,000
to 99,999 people is advantageous in several respects:
? Provides more time for PWSs that have not monitored for
Cryptosporidium previously to prepare for monitoring (PWSs serving at
least 100,000 people monitored for Cryptosporidium under the ICR). PWSs
can use this time to develop budgets, establish contracts with
Cryptosporidium laboratories, identify appropriate sampling locations,
and learn sampling procedures.
? Provides more time for Cryptosporidium analytical
laboratories to build capacity as needed to accommodate the sample
analysis needs of PWSs.
? Spreads out the transactional demand for regulatory
oversight. EPA anticipates that the period of greatest transactional
demand for States and EPA that oversee monitoring will be when PWSs
begin monitoring. The staggered schedule will allow States and EPA to
provide more assistance to individual PWSs.
? Eliminates the gap between the end of large PWS monitoring
and the start of small PWS monitoring (under the proposed rule
schedule, a gap of 18 months existed between the time that large PWSs
completed and small PWSs started Cryptosporidium monitoring). Such a
gap could create difficulties with maintaining Cryptosporidium sampling
and laboratory analysis expertise to support monitoring by small PWSs.
The timing of monitoring and treatment activities in today's rule
for PWSs serving fewer than 10,000 people is nearly identical to the
schedule in the August 11, 2003 proposed LT2ESWTR and reflects
recommendations by the Advisory Committee. The only change is allowing
these PWSs the option to spread their Cryptosporidium monitoring over
two years in order to facilitate budgeting for this monitoring.
However, this change does not affect the treatment compliance dates for
these PWSs.
Specifically, filtered PWSs serving fewer than 10,000 people
initially conduct one year of source water monitoring for E. coli or an
alternative indicator if approved by the State, beginning 30 months
after the rule is effective. At the conclusion of this monitoring,
these PWSs have six months to prepare for Cryptosporidium monitoring,
if required based on their indicator monitoring results. Filtered PWSs
that exceed the indicator trigger value and all unfiltered PWSs serving
fewer than 10,000 people must begin Cryptosporidium monitoring 48
months after the rule is effective. This Cryptosporidium monitoring may
consist of sampling twice-per-month for one year or once-per-month for
two years. PWSs must report their bin classification to the State for
approval within six months of the scheduled completion of
Cryptosporidium monitoring.
Regardless of the Cryptosporidium sampling frequency, PWSs serving
fewer than 10,000 people must comply with any additional
Cryptosporidium treatment requirements within 102 months (8.5 years)
after the rule is effective. States may allow an additional two years
for PWSs making capital improvements. PWSs must begin a second round of
source water monitoring for E. coli or an alternative State-approved
indicator within 11.5 years (138 months) after the rule is effective
(six years after the bin classification date for PWSs that sampled for
Cryptosporidium twice-per-month during initial source water monitoring).
In summary, the compliance schedule for today's rule maintains the
earliest compliance dates recommended by the Advisory Committee for
PWSs serving at least 100,000 people. These PWSs serve the majority of
people that consume water from surface sources. The schedule also
maintains the latest compliance dates the Advisory Committee
recommended, which apply to PWSs serving fewer than 10,000 people. EPA
has staggered compliance schedules for PWSs between these two size
categories in order to facilitate implementation of the rule.
3. Summary of Major Comments
EPA received significant public comment on the compliance schedule
in the August 11, 2003 proposal. Major issues raised by commenters
include providing more time for PWSs to prepare for monitoring, giving
States more time to oversee monitoring, ensuring that laboratory
capacity can accommodate the compliance schedule, and establishing
consistent schedules for consecutive PWSs. A summary of these comments
and EPA's responses follows.
Commenters were concerned that some PWSs, in particular PWSs
serving 10,000 to 50,000 people, would need more than the three months
allowed under the proposed rule to report sampling schedules for
monitoring. In order to develop sampling schedules, PWSs must establish
contracts with laboratories, which may involve using municipal
procurement procedures. For smaller PWSs, budgeting for this expense
may require substantial time and planning.
EPA recognizes this concern and today's final rule provides
significantly more time for many PWSs to submit sampling schedules.
Specifically, PWSs serving 50,000 to 99,999 people and those serving
10,000 to 49,999 people must submit sampling schedules 9 and 21 months
after the rule is effective, respectively. EPA believes that these PWSs
will have sufficient time to develop sampling schedules with these
compliance dates. Today's rule still requires PWSs serving at least
100,000 people to submit sampling schedules 3 months after the rule is
effective. Because these PWSs have monitored for Cryptosporidium
previously, however,

[[Page 719]]

EPA believes that this compliance date is feasible for these PWSs.
Several commenters recommended that States, rather than EPA,
oversee monitoring due to States' existing relationships with and
knowledge of their PWSs. Commenters were concerned that some States
will not participate in early implementation activities and indicated
that States would prefer monitoring to begin 24 months after rule
promulgation. States need sufficient time to become familiar with the
rule, train their staff, prepare primacy packages, and train PWSs.
In general, EPA would prefer that States oversee monitoring by
their PWSs and will work with States to facilitate their involvement
with rule implementation. Where States are unable to implement today's
rule, however, EPA is prepared to oversee implementation. Moreover, EPA
believes that the staggered compliance schedule in today's final rule
will enhance States' ability to implement the rule.
While EPA does not consider waiting until 24 months after rule
promulgation to start monitoring for all PWSs to be appropriate, most
PWSs will not begin monitoring until this time or later under today's
rule. Among large PWSs (i.e., those serving at least 10,000 people),
the majority are in the 10,000 to 49,999 person size category and these
PWSs do not begin monitoring until 24 months after rule promulgation.
Further, all PWSs serving fewer than 10,000 people do not begin
monitoring until 30 months after rule promulgation. These smaller PWSs
are likely to need the most assistance from States. By staggering
monitoring start dates, today's rule also reduces the number of PWSs
that will begin monitoring at any one time, when the most assistance
from regulatory agencies will be required.
Many commenters were concerned that the capacity at Cryptosporidium
analytical laboratories would not be sufficient for the proposed
implementation schedule. Commenters noted that the proposed rule
schedule had a break of 18 months between the end of large PWS
Cryptosporidium monitoring and the start of small PWS Cryptosporidium
monitoring and thought that this break would discourage laboratories
from making investments to improve capacity. Other commenters stated
that excess laboratory capacity exists and that upon indication that a
final rule is imminent, commercial laboratories will hire staff to
handle the expected number of samples. Laboratories will, however, need
time to train analysts.
EPA recognizes the concern with ensuring that capacity at
Cryptosporidium laboratories will be sufficient. Through EPA's
laboratory approval program (described in section IV.K), the Agency has
evaluated capacity at Cryptosporidium laboratories. Based on
information provided by laboratories, EPA believes that current
capacity at Cryptosporidium laboratories will be sufficient for the
monitoring that PWSs serving at least 100,000 people will begin six
months after the rule is effective. EPA expects that commercial
laboratories will increase capacity as needed to serve the demand of
smaller PWSs that begin monitoring later. Approximately six months are
required to train Cryptosporidium analysts. Consequently, the staggered
compliance schedule should allow time for laboratories to hire and
train staff as necessary. In addition, with the compliance schedule in
today's final rule, no break exists between the time that large PWSs
end and small PWSs begin Cryptosporidium monitoring. Thus, EPA has
eliminated this potential disincentive to laboratories investing in
capacity.
However, EPA will continue to monitor laboratory capacity and the
ability of PWSs to contract with laboratories to meet their monitoring
requirements under the LT2ESWTR. The Agency will assist with
implementation of the rule to help maximize the use of available
laboratory capacity by PWSs. If evidence emerges during implementation
of the rule that PWSs are experiencing problems with insufficient
laboratory capacity, the Agency will undertake appropriate action at
that time.
In regard to consecutive PWSs (i.e., PWSs that buy and sell treated
water), commenters recommended that compliance schedules in the Stage 2
DBPR and LT2ESWTR should be consistent. Some commenters also suggested
that where a small PWS sells water to a large PWS, the small PWS should
comply on the large PWS schedule. In response, today's final rule
requires PWSs that sell treated drinking water to other PWSs to comply
according to the schedule that applies to the largest PWS in the
combined distribution system. This approach will ensure that PWSs have
the same compliance schedule under both the LT2ESWTR and Stage 2 DBPR.

H. Public Notice Requirements

1. Today's Rule
Today's rule establishes the following public notice requirements:
? For violations of treatment technique requirements, which
today's rule establishes for Cryptosporidium treatment and for covering
or treating uncovered finished water reservoirs, PWSs must issue a Tier
2 public notice and must use existing health effects language (except
as provided below) for microbiological contaminant treatment technique
violations, as stated in 40 CFR 141 Subpart Q, Appendix B.
? For violations of monitoring and testing procedure
requirements, including the failure to collect one or two source water
Cryptosporidium samples, PWSs must issue a Tier 3 public notice. If the
State determines that a PWS has failed to collect three or more
Cryptosporidium samples, the PWS must provide a Tier 2 special public
notice. Violations for failing to monitor continue until the State
determines that the PWS has begun sampling on a revised schedule that
includes dates for collection of missed samples. This schedule may also
include a revised bin determination date where necessary.
? PWSs must report their bin classification no later than
six months after the end of the scheduled monitoring period (specific
dates in section IV.G.). Failure by a PWS to collect the required
number of Cryptosporidium samples to report its bin classification by
the compliance date is a treatment technique violation and the PWS must
provide a Tier 2 public notice. The treatment technique violation
persists until the State determines that the PWS is implementing a
State-approved monitoring plan to allow bin classification or will
install the highest level of treatment required under the rule. If the
PWS has already provided a Tier 2 special public notice for missing 3
sampling dates and is successfully meeting a State-approved schedule
for sampling and bin determination, it need not provide a second Tier 2
notice for missing the bin determination deadline in today's rule.
2. Background and Aalysis
In 2000, EPA published the Public Notification Rule (65 FR 25982,
May 4, 2000) (USEPA 2000b), which revised the general public
notification regulations for PWSs in order to implement the public
notification requirements of the 1996 SDWA amendments. This regulation
established the requirements that PWSs must follow regarding the form,
manner, frequency, and content of a public notice. Public notification
of violations is an integral part of the public health protection and
consumer right-to-know

[[Page 720]]

provisions of the 1996 SDWA Amendments.
Owners and operators of PWSs are required to notify persons served
when they fail to comply with the requirements of a NPDWR, have a
variance or exemption from the drinking water regulations, or are
facing other situations posing a risk to public health. The public
notification requirements divide violations into three categories (Tier
1, Tier 2 and Tier 3) based on the seriousness of the violations, with
each tier having different public notification requirements.
EPA has limited its list of violations and situations routinely
requiring a Tier 1 notice to those with a significant potential for
serious adverse health effects from short term exposure. Tier 1
violations contain language specified by EPA that concisely and in non-
technical terms conveys to the public the adverse health effects that
may occur as a result of the violation. States and water utilities may
add additional information to each notice, as deemed appropriate for
specific situations. A State may elevate to Tier 1 other violations and
situations with significant potential to have serious adverse health
effects from short-term exposure, as determined by the State.
Tier 2 public notices address other violations with potential to
have serious adverse health effects on human health. Tier 2 notices are
required for the following situations:
? All violations of the MCL, maximum residual disinfectant
level (MRDL) and treatment technique requirements, except where a Tier
1 notice is required or where the State determines that a Tier 1 notice
is required; and
? Failure to comply with the terms and conditions of any
existing variance or exemption. Tier 3 public notices include all other
violations and situations requiring public notice, including the
following situations:
? A monitoring or testing procedure violation, except where
a Tier 1 or 2 notice is already required or where the State has
elevated the notice to Tier 1 or 2; and
? Operation under a variance or exemption.
The State, at its discretion, may elevate the notice requirement
for specific monitoring or testing procedures from a Tier 3 to a Tier 2
notice, taking into account the potential health impacts and
persistence of the violation.
As part of the IESWTR, EPA established health effects language for
violations of treatment technique requirements for microbiological
contaminants. EPA believes this language, which was developed with
consideration of Cryptosporidium health effects, is appropriate for
violations of some Cryptosporidium treatment requirements under the
LT2ESWTR. However, for persistent monitoring violations and missing the
deadline for bin determination, EPA is promulgating alternative
language that better informs consumers of the nature and potential
health consequences of the violation.
As described in section IV.C, EPA proposed automatically
classifying PWSs in the highest treatment bin (Bin 4) if they fail to
complete required monitoring. For today's final rule, EPA has
determined that providing more flexibility to States in dealing with
PWSs that fail to monitor is appropriate. EPA also believes, however,
that responses to monitoring failures must reasonably ensure that PWSs
complete monitoring as required to determine a bin classification
within the compliance date, or as soon thereafter as possible.
Moreover, consistent with the public health protection and consumer
right-to-know provisions of the 1996 SDWA Amendments, consumers should
be informed of these monitoring failures.
Instead of the proposed automatic Bin 4 classification for
monitoring failures under today's rule, PWSs must provide a Tier 3
public notice for monitoring violations including up to two missed
Cryptosporidium samples. If a PWS misses three or more Cryptosporidium
samples (other than the specifically exempted situations described in
section IV.A.1.c), this persistent violation requires a Tier 2 public
notice. This elevated public notice level reflects significant concern
that persistent failure to collect required samples will result in the
PWS being unable to determine its Cryptosporidium treatment bin
classification and the corresponding required treatment level by the
compliance date.
Further, if a PWS is unable to determine a bin classification by
the compliance date due to failure to collect the required number of
Cryptosporidium samples, this is a treatment technique violation that
also requires a Tier 2 public notice, unless the system is already
complying with an alternate State-approved schedule for monitoring and
bin determination. A PWS that does not determine its bin classification
by the required date may not be able to comply with the Cryptosporidium
treatment technique requirements of today's rule by the required date
and provide the appropriate level of public health protection.
3. Summary of Major Comments
In the August 11, 2003, proposal, EPA requested comment on whether
violations of the treatment requirements for Cryptosporidium under the
LT2ESWTR should require a Tier 2 public notice and whether the proposed
health effects language is appropriate (USEPA 2003a). Most commenters
supported requiring a Tier 2 public notice for violations of
Cryptosporidium treatment requirements under the LT2ESWTR and agreed
that no new health effects language is needed for this notification.
One commenter stated that a failure to meet Cryptosporidium removal
requirements under LT2ESWTR should require Tier 1 public notice.
Today's final rule reflects the views of most commenters and is
consistent with existing regulations in requiring a Tier 2 public
notice for Cryptosporidium treatment technique violations. A State may
elevate a violation to Tier 1 if the State determines that the
violation creates significant potential for serious adverse health
effects from short-term exposure.
Another commenter agreed that Tier 2 notice was appropriate but
recommended that the LT2ESWTR and any associated guidance be more
explicit as to when a treatment technique violation occurs with the use
of microbial toolbox options. As described in section IV.D, EPA has
stated in today's final rule that failure by a PWS in any month to
demonstrate treatment credit with microbial toolbox options equal to or
greater than its Cryptosporidium treatment requirements is a treatment
technique violation. This violation lasts until the PWS demonstrates
that it is meeting criteria for sufficient treatment credit to satisfy
its Cryptosporidium treatment requirements.

I. Reporting Source Water Monitoring Results

This section presents specific reporting requirements that apply to
source water monitoring under today's rule, including EPA's data system
for reporting and reviewing monitoring results. For related
requirements, see section IV.A for monitoring parameters frequency,
section IV.J for required analytical methods, and section IV.K for
approved laboratories. General reporting requirements under today's
rule and associated compliance dates are shown in section IV.G.
1. Today's Rule
PWSs must report results from the required source water monitoring

[[Page 721]]

described in section IV.A no later than 10 days after the end of the
first month following the month when the sample is collected. For
Cryptosporidium analyses, PWSs must report the data elements specified
in Table IV.I-1. For samples in which at least 10 L is filtered and all
of the sample volume is analyzed, only the sample volume filtered and
the number of oocysts counted must be reported. Table IV.I-2 presents
the data elements that PWSs must report for E. coli and turbidity
analyses. PWSs, or approved laboratories acting as the PWSs' agents,
must retain results from Cryptosporidium and E. coli monitoring until
36 months after bin determination for the particular round of monitoring.

Table IV.I-1.--Cryptosporidium Data Elements To Be Reported
------------------------------------------------------------------------
Data element Reason for data element
------------------------------------------------------------------------
Identifying information:
PWSID.............................. Needed to associate plant with
public water system.
Facility ID........................ Needed to associate sample
result with facility.
Sample collection point............ Needed to associate sample
result with sampling point.
Sample collection date............. Needed to determine that
utilities are collecting
samples at the frequency
required.
Sample type (field or matrix spike) Needed to distinguish field
\1\. samples from matrix samples
for recovery calculations.
Sample results:
Sample volume filtered (L), to Needed to verify compliance
nearest \1/4\ L \2\. with sample volume
requirements.
Was 100% of filtered volume Needed to calculate the final
examined? \3\. concentration of oocysts/L and
determine if volume analyzed
requirements are met.
Number of oocysts counted.......... Needed to calculate the final
concentration of oocysts/L.
------------------------------------------------------------------------
\1\ For matrix spike samples, sample volume spiked and estimated number
of oocysts spiked must be reported. These data are not required for
field samples.
\2\ For samples in which < 10 L is filtered or < 100% of the sample volume
is examined, the number of filters used and the packed pellet volume
must also be reported to verify compliance with LT2ESWTR sample volume
analysis requirements. These data are not required for most samples.
\3\ For samples in which < 100% of sample is examined, the volume of
resuspended concentrate and volume of this resuspension processed
through IMS must be reported to calculate the sample volume examined.
These data are not required for most samples.

Table IV.I-2.--E. coli and Turbidity Data Elements To Be Reported
------------------------------------------------------------------------
Reason for collecting data
Data element element
------------------------------------------------------------------------
Identifying Information:
PWS ID............................. Needed to associate analytical
result with public water
system.
Facility ID........................ Needed to associate plant with
public water system.
Sample collection point............ Needed to associate sample
result with sampling point.
Sample collection date............. Needed to determine that
utilities are collecting
samples at the frequency
required.
Analytical method number........... Needed to associate analytical
result with analytical method.
Method Type........................ Needed to verify that an
approved method was used and
call up correct web entry
form.
Source water type.................. Needed to assess
Cryptosporidium indicator
relationships.
E. coli/100 mL..................... Sample result (although not
required, the laboratory also
will have the option of
entering primary measurements
for a sample into the LT2ESWTR
internet-based database to
have the database
automatically calculate the
sample result).
Turbidity Information:
Turbidity result................... Needed to assess
Cryptosporidium indicator
relationships.
------------------------------------------------------------------------

PWSs serving at least 10,000 people must submit sampling schedules
(described in section IV.A) and monitoring results for the initial
source water monitoring to EPA electronically at the following Internet
site: https://intranet.epa.gov/lt2/. These PWSs should instruct their
laboratories to electronically enter results at this site using web-
based manual entry forms or by uploading XML files (extensible markup
language files--a standard format that enables information exchange
between different systems) from laboratory information management
systems (LIMS). After laboratories enter sample results, PWSs must
review the results on-line at this site. The State may approve an
alternative approach for reporting source water monitoring schedules
and sample results if, for example, a PWS or laboratory does not have
the capability to report data electronically.
If a PWS believes that its laboratory entered a sample result into
the data system erroneously, the PWS may notify the laboratory to
rectify the entry. In addition, if a PWS believes that a result is
incorrect, the PWS may electronically mark the result as contested and
petition the State to invalidate the sample. If a PWS contests a sample
result, the PWS should submit a rationale to the State, including a
supporting statement from the laboratory, providing a justification.
PWSs may arrange with laboratories to review their sample results prior
to the results being entered into the EPA data system.
PWSs serving fewer than 10,000 people must submit sampling
schedules and monitoring results for the initial round of source water
monitoring to the State. Further, all PWSs must submit sampling
schedules and monitoring results for the second round of

[[Page 722]]

monitoring to the State. Regardless of the reporting process used, PWSs
must report an analytical monitoring result to the State no later than
10 days after the end of the first month following the month when the
sample was collected.
2. Background and Analysis
The reporting requirements for source water monitoring in today's
final rule reflect those in the August 11, 2003 proposed LT2ESWTR
(USEPA 2003a). The data elements that PWSs must report for
Cryptosporidium and E. coli analyses are the minimum necessary to
identify the sample, determine the sample concentration, and verify
that the PWS complied with rule requirements like minimum sample volume
and approved analytical methods. PWSs or laboratories must keep bench
sheets and slide reports for Cryptosporidium analyses for three years
after bin determination for the particular round of monitoring, at
which time PWSs must be in compliance with any additional
Cryptosporidium treatment requirements based on the monitoring results.
Due to the early implementation schedule, EPA expects to partner
with States to implement initial source water monitoring by large PWSs
under today's rule. EPA has developed an Internet-based data system to
allow electronic reporting and review of source water monitoring
results by laboratories, PWSs, States, and EPA. States may use this
data system to oversee monitoring by their PWSs. Where States are
unable to provide this oversight, the data system will allow EPA to
implement today's rule. Accordingly, PWSs serving at least 10,000
people must use this data system to report sampling schedules and
sample results for the initial round of source water monitoring unless
the State approves an alternative method for reporting.
EPA expects laboratories to report analytical results for
Cryptosporidium, E. coli, and turbidity analyses directly to the data
system using web forms and software that are available free of charge.
The data system will perform logic checks on data entered and will
calculate results from primary data where necessary. This is intended
to reduce reporting errors and limit the time involved in
investigating, checking, and correcting errors at all levels. The
LT2ESWTR proposal describes the analysis functions of the data system
in more detail (USEPA 2003a).
In general, EPA expects that States will implement the initial
source water monitoring by small PWSs and the second round of
monitoring by all PWSs. Thus, PWSs must submit sampling schedules and
monitoring results for this monitoring to the State. Note that where
States do not assume primacy for the rule, however, EPA will act as the
State.
3. Summary of Major Comments
EPA received significant public comment on the following aspects of
reporting requirements for source water monitoring in the August 11,
2003 proposed LT2ESWTR: the deadline for reporting sample results,
EPA's electronic data system, and reporting results to EPA rather than
the State. A summary of these comments and EPA's responses follows.
Some commenters were concerned with requiring PWSs to report sample
results no later than the 10th of the second month after the month when
the sample is collected. Commenters stated that this will cause most
PWSs to sample in the first part of the month, which will exacerbate
laboratory capacity problems. As an alternative, commenters recommended
that PWSs be required to report sample results 72 days after
collection. This approach would give all PWSs the same time period to
report sample results regardless of the collection date and would
facilitate PWSs and laboratories scheduling sample collection dates
more uniformly throughout the month.
In response, EPA believes that requiring PWSs to report monitoring
results by the 10th of the second month after sample collection is
appropriate. This will maintain consistency with existing drinking
water regulations, which typically require monitoring results to be
reported by the 10th of the following month. Thus, specifying this
reporting date under today's rule will avoid causing PWSs and States to
develop different reporting dates for different regulations. Due to the
time required for laboratories to analyze Cryptosporidium samples,
today's rule gives PWSs an extra month to report monitoring results;
i.e., the minimum time PWSs have to report results is approximately 40
days (one month plus 10 days). This time frame, however, is greater
than what is necessary for laboratories to analyze samples and for PWSs
to review results. Consequently, EPA does not believe that PWSs will
benefit by collecting a sample at the start of a month in comparison to
the end of a month.
Many commenters expressed concern with the readiness of the
electronic data system for reporting and reviewing monitoring results
under today's rule. Commenters stated that PWSs have experienced
significant problems with data systems that supported earlier rules,
such as the Information Collection Rule and the Unregulated Contaminant
Monitoring Rule. Commenters recommended that the data system be in
place and fully tested prior to finalization of the rule and that EPA
provide training for users. If the data system is not available when
the rule is finalized, commenters asked that the monitoring be delayed
as specified in the Agreement in Principle (USEPA 2000a).
EPA has ensured that the LT2 data system has been fully tested and
deployed prior to finalizing the rule. During development of the data
system, EPA has involved stakeholders in a joint requirements
workgroup, which has made recommendations for data system
characteristics and has participated in data system testing. EPA has
developed guidance and other training materials for PWSs, States, and
laboratories on how to use the data system and will provide technical
assistance on a ongoing basis to data system users. EPA believes these
steps will help to avoid problems that stakeholders experienced with
data systems for earlier rules.
Some commenters expressed concerns about large PWSs reporting
monitoring results to EPA. Commenters stated that implementation of the
rule should be administered by States, due to the existing
relationships States have with the PWSs they regulate. For States that
will implement the rule, commenters recommended allowing PWSs to report
to States, rather than EPA. Commenters also requested that EPA provide
copies of all monitoring data and PWS correspondence to States when
they assume primacy.
EPA will work with States to implement today's rule and to help
States assume as much responsibility for implementation as they can.
Through the LT2ESWTR data system, States will have full access to
monitoring results reported by their PWSs. Today's rule also allows
States to direct their PWSs to report monitoring results directly to
them, rather than EPA. Further, States may require PWSs to submit
descriptions of monitoring locations for approval. In general, EPA will
seek to involve States in any communications with and decisions for
their PWSs and will allow States to take responsibility for these
activities if they choose to do so. However, because monitoring for the
largest systems begins before States will have had time to assume
primacy, EPA must be prepared to oversee monitoring for these PWSs
where States are unable to do so.

[[Page 723]]

J. Analytical Methods

1. Analytical Methods Overview
Today's final rule requires public water systems to conduct
LT2ESWTR source water monitoring using approved methods for
Cryptosporidium, E. coli, and turbidity analyses. PWSs must meet the
quality control criteria stipulated by the approved methods and
additional method-specific requirements, as stated in this section.
Related requirements for reporting source water monitoring results and
using approved laboratories are discussed in sections IV.I and IV.K,
respectively.
EPA has developed guidance for sampling and analyses under the
LT2ESWTR. The Source Water Monitoring Guidance Manual for Public Water
Systems under the LT2ESWTR provides recommendations on activities like
collecting samples and setting up contracts with laboratories. The
Microbial Laboratory Manual for the LT2ESWTR provides information for
laboratories that conduct analyses. These guidance documents may be
requested from EPA's Safe Drinking Water Hotline, which may be
contacted as described in the FOR FURTHER INFORMATION CONTACT section
in the beginning of this notice, and are available on the Internet at
http://www.epa.gov/safewater/disinfection/lt2.
2. Cryptosporidium Methods
a. Today's Rule
Cryptosporidium analysis for source water monitoring under today's
rule must be conducted using either Method 1622: Cryptosporidium in
Water by Filtration/IMS/FA (EPA 815-R-05-001, USEPA 2005c) or Method
1623: Cryptosporidium and Giardia in Water by Filtration/IMS/FA (EPA
815-R-05-002, USEPA 2005d). Additional method requirements for today's
rule include the following:
? For each Cryptosporidium sample, at least a 10-L sample
volume must be analyzed unless a PWS meets one of the two exceptions
stated in this section. PWSs may collect and analyze greater than a 10-
L sample volume.
? The first exception to the sample volume requirement stems
from sample turbidity. If a sample is very turbid, it may generate a
large packed pellet volume upon centrifugation (a packed pellet refers
to the concentrated sample after centrifugation has been performed in
EPA Methods 1622 and 1623). Samples resulting in large packed pellets
must have the sample concentrate aliquoted into multiple ``subsamples''
for independent processing through IMS, staining, and examination. PWSs
are not required to analyze more than 2 mL of packed pellet volume per
sample.
? The second exception to the sample volume requirement
stems from filter clogging. In cases where the filter clogs prior to
filtration of 10 L, the PWS must analyze as much sample volume as can
be filtered by 2 filters, up to a packed pellet volume of 2 mL. This
condition applies only to filters that have been approved by EPA for
nationwide use with Methods 1622 and 1623--the Pall Gelman
EnvirochekTM and EnvirochekTM HV filters, the
IDEXX Filta-MaxTM foam filter, and the Whatman
CrypTestTM cartridge filter.
? Methods 1622 and 1623 include fluorescein isothiocyanate
(FITC) as the primary antibody stain for Cryptosporidium detection,
DAPI staining to detect nuclei, and DIC to detect internal structures.
Under today's rule, PWSs must report total Cryptosporidium oocysts as
detected by FITC as determined by the color (apple green or alternative
stain color approved for the laboratory under the Lab QA Program
described in section IV.K), size (4-6 micrometers) and shape (round to
oval). This total includes all of the oocysts identified as described
here, less any atypical organisms identified by FITC, DIC, or DAPI
(e.g., possessing spikes, stalks, appendages, pores, one or two large
nuclei filling the cell, red fluorescing chloroplasts, crystals,
spores, etc.).
? As required by Method 1622 and 1623, PWSs must have 1
matrix spike (MS) sample analyzed for each 20 source water samples. The
volume of the MS sample must be within ten percent of the volume of the
unspiked sample that is collected at the same time, and the samples
must be collected by splitting the sample stream or collecting the
samples sequentially. The MS sample and the associated unspiked sample
must be analyzed by the same procedure. MS samples must be spiked and
filtered in the laboratory. However, if the volume of the MS sample is
greater than 10 L, the PWS is permitted to filter all but 10 L of the
MS sample in the field, and ship the filtered sample and the remaining
10 L of source water to the laboratory. In this case, the laboratory
must spike the remaining 10 L of water and filter it through the filter
that was used to collect the balance of the sample in the field.
? Laboratories must use flow cytometer-counted spiking
suspensions for spiked QC samples.
b. Background and Analysis
The M-DBP Advisory Committee recommended the use of Methods 1622 or
1623 and a minimum sample volume of 10 L for source water
Cryptosporidium analyses under the LT2ESWTR. The August 11, 2003
proposed rule reflected these recommendations, with associated QC
requirements and exceptions to the minimum sample volume for samples
that are highly turbid or cause significant filter clogging (USEPA
2003a). Today's final rule is unchanged from the proposal in these respects.
Today's rule requires the use of methods 1622 or 1623 because they
are the best available methods that have undergone full validation
testing. As described in section III.E, these methods were used during
the ICRSS, where MS samples indicated a mean recovery and relative
standard deviation of 43 and 47 percent, respectively (Connell et al.
2000). EPA expects that PWSs will achieve comparable performance with
these methods during source water monitoring under today's rule. With
the minimum sample volume and QC requirements in today's rule, this
level of performance will be sufficient to assign PWSs to
Cryptosporidium treatment bins and realize the public health goals
intended by EPA and the Advisory Committee for the LT2ESWTR. EPA has
also approved these methods for ambient water monitoring under a
separate rulemaking (68 FR 43272, July 21, 2003) (USEPA 2003b).
The proposed LT2ESWTR required the use of April 2001 versions of
Methods 1622 or 1623 and requested comment on approving revised
versions of these methods in the final rule (USEPA 2003a). The revised
methods were included in the proposal as draft June 2003 versions. The
revisions in these versions included increased flexibility in some QC
requirements, clarification of certain method procedures, an increase
in the allowable sample storage temperature to 10[deg]C, the addition
of several approved analysis modifications, and other refinements (see
the proposed rule for details)(USEPA 2003a).
Today's rule requires the use of the revised versions of Methods
1622 and 1623. In the versions of these methods finalized with today's
rule, the upper temperature limit for sample receipt has been increased
to 20[deg]C. This change responds to public comment and recent
publications (Ware and Schafer 2005, Francy et al. 2004, Nichols et al.
2004). As described in section IV.A, PWSs may grandfather data
generated with earlier approved versions of these methods (i.e., 1999
or 2001 versions).

[[Page 724]]

c. Summary of Major Comments
Public comment on the August 11, 2003 proposed LT2ESWTR supported
approval of the revised versions of Methods 1622 and 1623, which
today's rule establishes for source water Cryptosporidium monitoring.
EPA also received comment regarding the lack of viability and
infectivity information with these methods and requirements for
analyzing QC samples.
Several commenters were concerned that Methods 1622 and 1623 do not
indicate whether a Cryptosporidium oocyst is viable and infectious.
While EPA recognizes that these methods do not provide information on
Cryptosporidium infectivity, EPA's analysis indicates that they can
perform effectively for identifying those PWSs that should provide
additional Cryptosporidium treatment (USEPA 2005a). This analysis is
based on the actual performance of these methods in the ICRSS. Further,
EPA and the M-DBP Advisory Committee, which recommended Methods 1622
and 1623, accounted for this lack of information on infectivity when
designing the Cryptosporidium treatment bins in today's rule. EPA has
not identified any feasible methods for quantifying Cryptosporidium
infectivity in a national monitoring program.
Several commenters suggested that laboratories should only be
required to perform one OPR test per day instead of one for every 20
samples, as Methods 1622 and 1623 require. EPA believes, however, that
the frequency of one OPR test per 20 samples is appropriate for
identifying and correcting problems. For example, if an OPR test is
performed once per day for a laboratory that processes 60 samples per
day, a problem that occurs at sample 10 will be continued through the
next 50 samples. If an OPR test is performed once per 20 samples, a
problem that occurs at sample 10 would only affect 10 additional
samples. Consequently, EPA is maintaining the current QC criteria in
Methods 1622 and 1623.
3. E. coli Methods
a. Today's Rule
For enumerating source water E. coli density under the LT2ESWTR,
EPA is approving the same methods that are currently approved for
ambient water monitoring under 40 CFR 136.3. EPA established these
methods through the rulemaking ``Guidelines Establishing Test
Procedures for the Analysis of Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water'' (USEPA 2003b). Table IV.J-1
summarizes these methods. Method identification numbers are provided
for applicable standards published by EPA and voluntary consensus
standards bodies including Standard Methods, American Society of
Testing Materials (ASTM), and the Association of Analytical Chemists (AOAC).

Table IV.J-1.--List of Approved Analytical Methods for E. coli 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Standard Methods 18th,
Method EPA 19th, 20th Ed. ASTM AOAC Other
--------------------------------------------------------------------------------------------------------------------------------------------------------
MPN 2 3 4, multiple tube........... ...................... 9221B.1/9221F 5 6 7...
Multiple tube/multiple well........ ...................... 9223B 5 8............. ..................... 991.15 9............. Colilert[supreg]
8
10, Colilert-
18[supreg]
8 10 11.
MF 2 3 12 13 14 two step, or....... 1103.1 16............. 9222B/9222G5 15 9213D D5392-93 17..........
5.
Single step........................ 1603 18, 1604 19...... ...................... ..................... ..................... mColiBlue 24 20.
--------------------------------------------------------------------------------------------------------------------------------------------------------
1 Recommended for enumeration of E. coli in ambient water only, number per 100 ml.
2 Tests must be conducted to provide organism enumeration (density). Select the appropriate configuration of tubes/filtrations and dilutions/volumes to
account for the quality, character, consistency, and anticipated organism density of the water sample.
3 To assess the comparability of results obtained with individual methods, it is suggested that side-by-side tests be conducted across seasons of the
year with the water samples routinely tested in accordance with the most current Standard Methods for the Examination of Water and Wastewater or EPA
alternate test procedure (ATP) guidelines.
4 Samples shall be enumerated by the multiple-tube or multiple-well procedure. Using multiple-tube procedures, employ an appropriate tube and dilution
configuration of the sample as needed and report the Most Probable Number (MPN). Samples tested with Colilert[supreg]
may be enumerated with the
multiple-well procedures, Quanti-tray[supreg], or Quanti-tray[supreg]
2000, and the MPN calculated from the table provided by the manufacturer.
5 APHA. 1998, 1995, 1992. Standard Methods for the Examination of Water and Wastewater. American Public Health Association. 20th, 19th, and 18th
Editions. Amer. Publ. Hlth. Assoc., Washington, DC.
6 The multiple-tube fermentation test is used in 9221.B.1. Lactose broth may be used in lieu of lauryl tryptose broth (LTB), if at least 25 parallel
tests are conducted between this broth and LTB using the water samples normally tested, and this comparison demonstrates that the false-positive rate
and false-negative rate for total coliform using lactose broth is less than 10 percent. No requirement exists to run the completed phase on 10 percent
of all total coliform-positive tubes on a seasonal basis.
7 After prior enrichment in a presumptive medium for total coliform using 9221B.1, all presumptive tubes or bottles showing any amount of gas, growth or
acidity within 48± 3 h of incubation shall be submitted to 9221F. Commercially available EC-MUG media or EC media supplemented in the
laboratory with 50 [mu]g/ml of MUG may be used.
8 These tests are collectively known as defined enzyme substrate tests, where, for example, a substrate is used to detect the enzyme glucuronidase
produced by E. coli.
9 AOAC. 1995. Official Methods of Analysis of AOAC International, 16th Edition, Volume 1, Chapter 17. Association of Official Analytical Chemists
International. 481 North Frederick Avenue, Suite 500, Gaithersburg, Maryland 20877-2417.
10 Descriptions of the Colilert[supreg], Colilert-18[supreg], Quanti-Tray[supreg]
and Quanti-Tray[supreg]
2000 may be obtained from IDEXX Laboratories,
Inc., One IDEXX Drive, Westbrook, Maine 04092.
11 Colilert-18[supreg]
is an optimized formulation of the Colilert[supreg]
for the determination of total coliforms and E. coli that provides results
within 18 h of incubation at 35 [deg]C rather than the 24 h required for the Colilert[supreg]
test and is recommended for marine samples.
12 A 0.45 [mu]m membrane filter (MF) or other pore size certified by the manufacturer to fully retain organisms to be cultivated and to be free of
extractables which could interfere with their growth.
13 Because the MF technique usually yields low and variable recovery from chlorinated wastewaters, the Most Probable Number method will be required to
resolve any controversies.
14 When the MF method has not been used previously to test ambient water with high turbidity, large number of noncoliform bacteria, or samples that may
contain organisms stressed by chlorine, a parallel test should be conducted with a multiple-tube technique to demonstrate applicability and
comparability of results.
15 Subject total coliform positive samples as determined by 9222B or other membrane filter procedure to 9222G using NA-MUG media.
16 USEPA. 2002c. Method 1103.1: Escherichia coli (E. coli) In Water By Membrane Filtration Using membrane-Thermotolerant Escherichia coli Agar (mTEC).
U.S. Environmental Protection Agency, Office of Water, Washington, DC. EPA-821-R-02-020.
17 ASTM. 2000, 1999, 1996. Annual Book of ASTM Standards--Water and Environmental Technology. Section 11.02. American Society for Testing and Materials.
100 Barr Harbor Drive, West Conshohocken, PA 19428.

[[Page 725]]

18 USEPA. 2002. Method 1610: Escherichia coli (E. coli) In Water By Membrane Filtration Using Modified membrane-Thermotolerant Escherichia coli Agar
(modified mTEC). U.S. Environmental Protection Agency, Office of Water, Washington, DC. EPA-821-R-02-023.
19 Preparation and use of MI agar with a standard membrane filter procedure is set forth in the article, Brenner et al. 1993. ``New Medium for the
Simultaneous Detection of Total Coliform and Escherichia coli in Water.'' Appl. Environ. Microbiol. 59:3534-3544 and in USEPA. 2002. Method 1604:
Total Coliforms and Escherichia coli (E. coli) in Water by Membrane Filtration by Using a Simultaneous Detection Technique (MI Medium). U.S.
Environmental Protection Agency, Office of Water, Washington, DC. EPA-821-R-02-024.
20 A description of the mColiBlue24 test, Total Coliforms and E. coli, is available from Hach Company, 100 Dayton Ave., Ames, IA 50010.

For most PWSs, the time from sample collection to initiation of
analysis (i.e., the holding time) for source water E. coli samples may
not exceed 30 hours for all approved E. coli methods. However, if the
State determines on a case-by-case basis that analyzing an E. coli
sample within 30 hours is not feasible, the State may approve the
holding of an E. coli sample for up to 48 hours between collection and
initiation of analysis. E. coli samples held between 30 to 48 hours
must be analyzed by the Colilert reagent version of Standard Method
9223B as listed in 40 CFR 136.3. All E. coli samples must be maintained
below 10[deg]
C and not allowed to freeze.
The E. coli sample holding time established for source water
monitoring under the LT2ESWTR does not apply to E. coli sample holding
time requirements that have been established under other programs and
regulations.
b. Background and Analysis
In the August 11, 2003 proposed LT2ESWTR, EPA planned to approve
the same E. coli methods that the Agency had proposed for ambient water
monitoring in an earlier rulemaking, ``Guidelines Establishing Test
Procedures for the Analysis of Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water'' (USEPA 2001h). EPA selected
these methods based on data generated by EPA laboratories, submissions
to the EPA alternate test procedures program and voluntary consensus
standards bodies, peer reviewed journal articles, and publicly
available study reports.
On July 21, 2003, EPA finalized ``Guidelines Establishing Test
Procedures for the Analysis of Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water'' (USEPA 2003b). The only method
from the proposal of this rule that was not included in the final rule
was Colisure, which was excluded due to insufficient data on its
performance with surface water. For the other methods, EPA revised
certain titles and added method numbers to be consistent with other
microbiological methods, but the technical content of these methods in
the final rule did not change from the versions included in the
proposed rule.
EPA is approving these same E. coli methods for analyses under the
LT2ESWTR. The source water E. coli analyses that PWSs will conduct
under the LT2ESWTR are similar to the ambient water analyses for which
EPA approved E. coli methods under ``Guidelines Establishing Test
Procedures for the Analysis of Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water'' (USEPA 2003b). EPA continues
to support the findings of this rule and believes that the E. coli
methods approved therein have the necessary sensitivity and specificity
to meet the data quality objectives of the LT2ESWTR.
An important aspect of monitoring for E. coli is the allowable
sample holding time (i.e., the time between sample collection and
initiation of analysis). Existing regulations, such as 40 CFR 141.74,
limit the holding time for E. coli samples to 8 hours. However, for
PWSs that must ship E. coli samples to an off-site laboratory for
analysis, meeting an 8 hour holding time is generally not feasible. For
example, during the ICRSS, all of the PWSs that shipped samples off-
site for E. coli analysis exceeded an 8 hour holding time, and 12
percent of these samples had holding times in excess of 30 hours.
While most large PWSs that will monitor for E. coli under the
LT2ESWTR will conduct these analyses on-site, most small PWSs must ship
samples off-site to an approved laboratory. To address the concern that
PWSs using off-site laboratories cannot meet an 8-hour holding time,
EPA participated in studies to assess the effect of increased sample
holding time on E. coli analysis results. These studies are summarized
in the proposed rule (USEPA 2003a) and are described in detail in Pope
et al. (2003). Based on these studies, EPA has concluded that the
holding time for E. coli samples can be extended beyond 8 hours prior
to analysis without compromising the data quality objectives of
LT2ESWTR monitoring.
In the proposed LT2ESWTR, EPA required analysis of E. coli samples
to be initiated within 24 hours of sample collection and required that
samples be kept below 10[deg]
C and not allowed to freeze (USEPA
2003a). These proposed requirements were based on data showing that
most samples maintained within these temperature conditions were not
significantly different at 24 hours than at the standard holding time
of 8 hours. The proposal also noted that data indicated no significant
sample degradation after longer time periods, such as 30 or 48 hours,
for certain methods. Accordingly, EPA requested comment on establishing
a longer E. coli holding time in the final rule.
For today's final rule, EPA is establishing a holding time of 30
hours for all approved E. coli methods. After reviewing public comment
on this issue, which is summarized in the following section, and
reassessing the studies described in the proposed rule, EPA has
concluded that a 30 hour holding time limit for E. coli samples is
appropriate and consistent with the data quality objectives of LT2ESWTR
source water monitoring. Further, EPA believes that meeting a 30 hour
holding time is feasible for most PWSs that must ship E. coli samples
to an off-site laboratory for analysis. This longer holding time,
however, does not apply to E. coli monitoring conducted under other
programs and regulations.
EPA recognizes that in rare cases, having an E. coli sample
analyzed within 30 hours may not be feasible for a PWS due to distance
to an approved laboratory and limited transportation options. In these
cases, today's rule allows the State to approve up to a 48 hour holding
time for E. coli samples. Samples held between 30 to 48 hours must be
analyzed by the Colilert reagent version of Standard Method 9223B. This
is the only method evaluated in Pope et al. (2003) where no significant
sample degradation occurred at 48 hours.
PWSs must maintain samples below 10[deg]C and not allow them to
freeze. EPA has developing guidance for PWSs on packing and shipping E.
coli samples to maintain these temperature conditions. See the overview
at the beginning of this section for information on how to access this
guidance.
c. Summary of Major Comments
In the August 11, 2003 LT2ESWTR proposal, EPA requested comment on
whether the E. coli methods proposed for approval under the LT2ESWTR
are appropriate and whether there are additional methods not proposed
that should be considered. EPA also requested comment on the proposal
to extend the holding time for E. coli

[[Page 726]]

samples to 24 hours; whether EPA should limit the extended holding time
to only those E. coli analytical methods that were evaluated in the
holding time studies described in the proposal; and whether EPA should
increase the source water E. coli holding time to 30 or 48 hours for
samples evaluated by one method, ONPG-MUG, and retain a 24-hour holding
time for samples analyzed by other methods.
Most commenters stated that the proposed E. coli analytical methods
are appropriate. Commenters also agreed with the proposal to extend the
holding time for source water E. coli samples, but recommendations
about the maximum holding time and the methods to which the extended
holding time should apply differed among commenters. Some suggested
that EPA increase the holding time to 30 hours for the ONPG-MUG method,
but retain a 24-hour holding time for the other methods. Other
commenters recommended a 48-hour holding time for some or all methods.
Several commenters advised that holding times for all methods should be
the same to limit confusion. Some commenters were concerned that a 30-
hour holding time would not be sufficient for small PWSs in remote
areas to ship samples to distant laboratories.
After consideration of the comments received, as well as the
holding time study data presented in the proposed rule and the time
required to ship samples off-site for analysis as evidenced in the
ICRSS, EPA has concluded that allowing a 30-hour holding time for all
E. coli methods approved under today's final rule is appropriate. Data
indicate that a 30-hour holding time for E. coli samples will not
adversely impact the data quality objectives of LT2ESWTR monitoring.
Further, establishing the same holding time for all methods will limit
confusion, and a 30-hour holding time will allow most PWSs that ship
samples off site for analysis to meet the holding time requirements.
Today's rule also allows the State to authorize a 48-hour holding time
for rare cases where a 30-hour holding time is not feasible.
4. Turbidity Methods
a. Today's Rule
Today's rule requires PWSs to use the analytical methods that have
been previously approved by EPA for analysis of turbidity in drinking
water, as listed in 40 CFR 141.74. These are Method 2130B as published
in Standard Methods for the Examination of Water and Wastewater (APHA
1992), EPA Method 180.1 (USEPA 1993), Great Lakes Instruments Method 2
(Great Lakes Instruments 1992), and Hach FilterTrak Method 10133.
b. Background and Analysis
As stated in section IV.A, today's rule requires filtered PWSs
serving at least 10,000 people to monitor for turbidity when they
conduct source water monitoring. EPA may use these data to modify the
indicator criteria that trigger Cryptosporidium monitoring by small
filtered PWSs, as recommended by the M-DBP Advisory Committee (USEPA
2000a). In addition, PWSs using conventional or direct filtration may
achieve additional Cryptosporidium treatment credit by demonstrating
very low turbidity in the combined filter effluent, as described in
section IV.D.7, or the individual filter effluent, as described in
section IV.D.8.
The August 11, 2003 proposed LT2ESWTR required PWSs to use
turbidity methods that EPA had previously approved under 40 CFR 141.74
for analyzing drinking water (USEPA 2003a). These are EPA Method 180.1
and Standard Method 2130B, which are based on a comparison of the
intensity of light scattered by the sample with the intensity of light
scattered by a standard reference suspension; Great Lakes Instruments
Method 2, which is a modulated four beam infrared method using a
ratiometric algorithm to calculate the turbidity value from the four
readings that are produced; and Hach FilterTrak (Method 10133), which
is a laser-based method used to analyze finished drinking water.
Today's final rule is unchanged from the proposal in regard to
analytical methods for turbidity. Hence, PWSs must use methods
currently approved in 40 CFR 141.74 for turbidity analysis. EPA
believes the currently approved methods are appropriate for turbidity
analyses that will be conducted under the LT2ESWTR. PWSs must use
turbidimeter instruments as described in the EPA-approved methods,
which may be either on-line or bench top instruments. If a PWS chooses
to use on-line instruments for monitoring turbidity, the PWS must
validate the continuous measurements for accuracy on a regular basis
using a protocol approved by the State, as required in 40 CFR 141.74.
c. Summary of Major Comments
EPA received public comment on the turbidity methods required in
the August 11, 2003 proposed LT2ESWTR. While commenters, in general,
agreed that currently approved turbidity methods are adequate to meet
the requirements of the rule, several commenters were concerned with
turbidity measurement variation among different instruments. One
commenter suggested voluntary third party testing, while another
recommended more rigorous calibration and verification processes.
As described in section IV.D.7, EPA has reviewed studies of low
level turbidity measurements, as well as standard test methods for
measurement of turbidity below 5 NTU. After reviewing this information,
EPA concluded that currently available monitoring equipment can
reliably measure turbidity at levels of 0.15 NTU and lower. However,
EPA agrees that rigorous calibration and maintenance of turbidity
monitoring equipment is necessary for PWSs pursuing the low filtered
water turbidity performance options in the microbial toolbox. EPA has
developed guidance on proper calibration, operation, and maintenance of
turbidimeters (USEPA 1999c).
A few commenters stated that the LT2ESTWR does not recognize
advancements in turbidity measurement and newly developed turbidity
measurement technologies. In response, EPA has not received information
that supports approval of analytical methods for turbidity in addition
to those currently approved under 40 CFR 141.74, which are also
approved for turbidity monitoring under today's rule. If other
turbidity methods are approved and added to 40 CFR 141.74 in the
future, these methods will also be approved under the LT2ESWTR.
One commenter requested that the LT2ESWTR specifically address
turbidity measurements in plants that practice lime softening. EPA
notes that additional treatment credit for combined filter effluent
turbidity is based on measurements collected under 40 CFR 141.173 or 40
CFR 141.551 (the IESWTR or LT1ESWTR). These regulations allow PWSs that
use lime softening to acidify samples prior to analysis in order to
address the effects of lime softening on turbidity measurements. In
regard to treatment credit based on individual filter effluent
turbidity, EPA does not believe that acidifying samples while measuring
turbidity every 15 minutes at each individual filter, as the IESWTR and
LT1ESWTR require, is feasible. However, PWSs that practice lime
softening could use the demonstration of performance toolbox option to
demonstrate that a plant is achieving removal efficiencies equivalent
to the additional credit allowed for individual filter performance.

[[Page 727]]

K. Laboratory Approval

Given the potentially significant implications for PWSs and
drinking water consumers of microbial monitoring under the LT2ESWTR,
laboratory analyses for Cryptosporidium, E. coli, and turbidity should
be accurate and reliable within the limits of approved methods.
Therefore, today's final rule requires PWSs to use laboratories that
have been approved to conduct analyses for these parameters by EPA or
the State.
1. Cryptosporidium Laboratory Approval
a. Today's Rule
Analysis of samples for Cryptosporidium under today's rule must be
conducted by a laboratory that is approved under EPA's Laboratory
Quality Assurance Evaluation Program (Lab QA Program) for Analysis of
Cryptosporidium in Water (described in 67 FR 9731, March 4, 2002, USEPA
2002d). A list of laboratories that are approved under this program is
available on the Internet at http://www.epa.gov/safewater/disinfection/lt2. If
a State adopts an equivalent approval process under a State laboratory
certification program, then PWSs can use laboratories approved by the
State.
b. Background and Analysis
Because States do not currently approve laboratories for
Cryptosporidium analyses, EPA has assumed initial responsibility for
Cryptosporidium laboratory approval. EPA initiated the Cryptosporidium
Lab QA Program prior to LT2ESWTR promulgation to ensure that adequate
analytical capacity will be available at approved laboratories to
support required monitoring, which begins 6 months after rule
promulgation. The August 11, 2003 proposed LT2ESWTR required PWSs to
have Cryptosporidium samples analyzed by laboratories approved under
the EPA Lab QA Program. Today's final rule is unchanged from the
proposal with respect to this requirement.
Laboratories seeking approval under the EPA Lab QA Program for
Cryptosporidium analysis must submit an interest application to EPA,
successfully analyze a set of initial performance testing samples, and
undergo an on-site evaluation. Laboratories that pass the quality
assurance evaluation are approved for Cryptosporidium analysis under
the LT2ESWTR. To maintain approval, laboratories must successfully
analyze a set of three ongoing proficiency testing samples
approximately every four months. The Lab QA Program is described in
detail in USEPA (2002d) and additional information can be found on the
Internet at http://www.epa.gov/safewater/disinfection/lt2.
EPA tracks the Cryptosporidium sample analysis capacity of approved
laboratories through the Lab QA Program. Using information provided by
laboratories, EPA expects that existing capacity should be sufficient
to support initial source water monitoring by large PWSs under the
LT2ESWTR. Further, the implementation schedule for today's rule, which
is described in section IV.G, provides time for laboratories to
increase capacity through steps like training new analysts as the
demand for sample analysis grows.
c. Summary of Major Comments
In regard to approval of laboratories for Cryptosporidium analysis,
major comments on the August 11, 2003 proposal addressed the following
issues: laboratory capacity, State approval programs, and analyst
experience criteria. Comments regarding Cryptosporidium laboratory
capacity are summarized in section IV.G, while those on the other
issues are summarized as follows.
EPA requested comment on States approving Cryptosporidium
laboratories. Most commenters, however, recommended that EPA maintain
the Lab QA Program, due to the specialized nature of the work. EPA
intends to maintain the Lab QA Program, but today's rule does allow
States to certify Cryptosporidium laboratories by setting up an
equivalent program.
EPA also requested comment on the experience criteria that Methods
1622 and 1623 include for Cryptosporidium analysts. Some commenters
recommended lowering analyst training and experience requirements,
while others recommended no change or an increase in microscopy
training. After evaluating these comments, EPA has concluded that the
analyst criteria included in Methods 1622 and 1623 are reasonable for
ensuring that analysts have the experience to evaluate source water
samples under today's rule. Consequently, EPA has not altered these
criteria from the approved methods.
2. E. coli Laboratory Approval
a. Today's Rule
PWSs must have E. coli samples analyzed by a laboratory that has
been certified by EPA, the National Environmental Laboratory
Accreditation Conference (NELAC) or the State for total coliform or
fecal coliform analysis in drinking water under 40 CFR 141.74. The
laboratory must use the same technique for E. coli analysis under
today's rule that the laboratory is certified to use for drinking water
under 40 CFR 141.74 (e.g., membrane filtration, multiple-well,
multiple-tube).
b. Background and Analysis
The August 11, 2003 proposed LT2ESWTR required PWSs to have E. coli
samples analyzed by laboratories that are certified to conduct total or
fecal coliform analyses in drinking water (i.e., under 40 CFR 141.74)
by EPA, NELAC or the State. The proposal required laboratories to use
the same E. coli analytical technique that they are certified to use
for coliform analyses in drinking water. Today's final rule is
unchanged from the proposal in regard to these requirements. EPA
believes that laboratories that are certified to conduct coliform
analyses in drinking water have the expertise to conduct E. coli
analyses under today's rule, provided they use the analytical technique
for which they are certified.
c. Summary of Major Comments
Two commenters on the August 11, 2003 proposal suggested that
laboratories should be certified specifically for quantitative analyses
of total or fecal coliform in a source water matrix. However, the
methods approved for source water E. coli analyses under today's rule
are also approved under the drinking water certification program. EPA
believes that analysts certified for these methods under the drinking
water certification program have the capability to perform the same
methods for a source water matrix, even though additional steps may be
required (such as dilutions). EPA has revised the Laboratory
Certification Manual to suggest Performance Evaluation (PE) samples for
source water matrix analyses and States have the option to require PE
samples as needed in their State laboratory certification programs.
3. Turbidity Analyst Approval
a. Today's Rule
Under today's rule, measurements of turbidity must be made by a
party approved by the State.
b. Background and Analysis
The August 11, 2003 proposed LT2ESWTR required that measurements of
turbidity be made by a party approved by the State. This reflects
existing requirements in 40 CFR 141.74 for measurement of turbidity in
drinking water. Today's final rule is unchanged from the proposal in
this respect.

[[Page 728]]

c. Summary of Major Comments
Commenters on requirements for turbidity analyst approval in the
August 11, 2003 proposal agreed that turbidity analyses should be
consistent with 40 CFR 141.74. Specifically, any person that is
currently approved to conduct turbidity analysis under existing
drinking water regulations should be approved to conduct turbidity
analyses under the LT2ESWTR. EPA agrees with this comment and it is
reflected in today's final rule.

L. Requirements for Sanitary Surveys Conducted by EPA

1. Today's Rule
Today's final rule establishes requirements for PWSs to respond to
significant deficiencies identified in sanitary surveys that EPA
conducts. These requirements give EPA authority equivalent to that
exercised by States under existing regulations to ensure that PWSs
address significant deficiencies.
? For sanitary surveys conducted by EPA under SDWA section
1445 or other authority, PWSs must respond in writing to significant
deficiencies outlined in sanitary survey reports no later than 45 days
after receipt of the report, indicating how and on what schedule the
PWS will address significant deficiencies noted in the survey.
? PWSs must correct significant deficiencies identified in
sanitary survey reports according to the schedule approved by EPA, or
if there is no approved schedule, according to the schedule the PWS
reported if such deficiencies are within the control of the PWS.
? A sanitary survey, as conducted by EPA, is an onsite
review of the water source (identifying sources of contamination by
using results of source water assessments where available), facilities,
equipment, operation, maintenance, and monitoring compliance of a PWS
to evaluate the adequacy of the PWS, its sources and operations, and
the distribution of safe drinking water. A significant deficiency
includes a defect in design, operation, or maintenance, or a failure or
malfunction of the sources, treatment, storage, or distribution system
that EPA determines to be causing, or has the potential for causing the
introduction of contamination into the water delivered to consumers.
2. Background and Analysis
As established by the IESWTR in 40 CFR 142.16(b)(3), primacy States
must conduct sanitary surveys for PWSs using surface water sources
every three or five years. The sanitary survey is an onsite review of
the following: (1) Source, (2) treatment, (3) distribution system, (4)
finished water storage, (5) pumps, pump facilities, and controls, (6)
monitoring, reporting, and data verification, (7) system management and
operation, and (8) operator compliance with State requirements.
Under the IESWTR, primacy States must have the authority to assure
that PWSs respond in writing to significant deficiencies identified in
sanitary survey reports no later than 45 days after receipt of the
report, indicating how and on what schedule the system will address the
deficiency (40 CFR 142.16(b)(1)(ii)). Further, primacy States must have
the authority to assure that systems take necessary steps to address
significant deficiencies identified in sanitary survey reports if such
deficiencies are within the control of the system and its governing
body (40 CFR 142.16(b)(1)(iii)).
EPA conducts sanitary surveys under SDWA section 1445 for PWSs not
regulated by primacy States (e.g., Tribal systems, Wyoming). However,
the authority required of primacy States under 40 CFR 142 to ensure
that PWSs address significant deficiencies identified during sanitary
surveys does not extend to EPA. Consequently, the sanitary survey
requirements established by the IESWTR created an unequal standard.
PWSs regulated by primacy States are subject to the States' authority
to require correction of significant deficiencies noted in sanitary
survey reports, while PWSs for which EPA has direct implementation
authority did not have to meet an equivalent requirement.
In the August 11, 2003 proposal, EPA requested comment on
establishing requirements under 40 CFR 141 for PWSs to correct
significant deficiencies identified in sanitary surveys conducted by
EPA. The requirements in today's final rule follow closely on the
language presented in the proposal. Today's rule ensures that PWSs in
non-primacy States are subject to comparable requirements for sanitary
surveys as PWS regulated by States with primacy.
3. Summary of Major Comments
Most public comment on the August 11, 2003 proposal supported
requiring PWSs to correct significant deficiencies identified in
sanitary surveys conducted by EPA. Commenters stated that requirements
for sanitary surveys should be consistent for PWSs and should not
depend on the primacy agency. EPA believes the requirements in today's
final rule will establish this consistency.
One commenter requested that EPA include a process for PWSs to
appeal a significant deficiency determination. EPA expects that PWSs
will raise any concerns regarding significant deficiency determinations
with the primacy agency, either the State or EPA, that conducts the
sanitary survey. States or EPA may withdraw or amend their significant
deficiency determinations as appropriate. The IESWTR did not establish
a separate appeal process for sanitary surveys conducted by States, and
EPA has not established such a process for sanitary surveys conducted
by EPA under today's rule.

M. Variances and Exemptions

SDWA section 1415 allows States to grant variances from national
primary drinking water regulations under certain conditions; section
1416 establishes the conditions under which States may grant exemptions
to MCL or treatment technique requirements. These conditions and EPA's
view on their applicability to the LT2ESWTR are summarized as follows:
1. Variances
Section 1415 specifies two provisions under which general variances
to treatment technique requirements may be granted:

(1) A State that has primacy may grant a variance to a PWS from
any requirement to use a specified treatment technique for a
contaminant if the PWS demonstrates to the satisfaction of the State
that the treatment technique is not necessary to protect public
health because of the nature of the PWS's raw water source. EPA may
prescribe monitoring and other requirements as conditions of the
variance (section 1415(a)(1)(B)).
(2) EPA may grant a variance from any treatment technique
requirement upon a showing by any person that an alternative
treatment technique not included in such requirement is at least as
efficient in lowering the level of the contaminant (section 1415(a)(3)).

EPA does not believe that the first variance provision is
applicable to filtered PWSs under today's rule. Filtered PWSs are
required to implement additional treatment under the LT2ESWTR only when
source water monitoring demonstrates higher levels of Cryptosporidium
contamination. Thus, this treatment technique requirement accounts for
the nature of the PWS's raw water source. Unfiltered PWS treatment
requirements also account for the nature of a PWS's raw water source
with respect to whether 2-or 3-log Cryptosporidium inactivation is required.
In theory, the first variance provision could be applied to the
requirement that all unfiltered PWSs provide at least 2-

[[Page 729]]

log Cryptosporidium inactivation. If an unfiltered PWS could show a raw
water Cryptosporidium level 3-log lower than the Bin 1 cutoff for
filtered PWSs (i.e., below 0.075 oocysts/1,000 L), this could
demonstrate that no treatment for Cryptosporidium is necessary. The
unfiltered PWS would already be achieving public health protection
against Cryptosporidium equivalent to filtered PWSs due to the nature
of the raw water source.
In practice, EPA has not identified an approach that is
economically or technologically feasible for a PWS to demonstrate such
a low level of Cryptosporidium to support granting a variance. This is
due to the extremely large volume and number of samples that would be
necessary to make such a demonstration with confidence. However,
unfiltered PWSs may choose to pursue the development and implementation
of monitoring programs to apply for a variance from Cryptosporidium
inactivation requirements based on the nature of the raw water source.
A sufficient monitoring program may be feasible in site-specific
circumstances or with the use of innovative approaches.
The second provision for granting a variance is not applicable to
the LT2ESWTR because the rule provides broad flexibility in how PWSs
achieve the required level of Cryptosporidium reduction through the
microbial toolbox. Moreover, the microbial toolbox contains an option
for Demonstration of Performance, under which States can award
treatment credit based on the demonstrated efficiency of a treatment
process in reducing Cryptosporidium levels. Thus, there is no need for
this type of variance under the LT2ESWTR.
SDWA section 1415(e) describes small PWS variances, but these
cannot be granted for a treatment technique for a microbial
contaminant. Hence, small PWS variances are not allowed for the LT2ESWTR.
2. Exemptions
Under SDWA section 1416(a), a State may exempt any PWS from a
treatment technique requirement upon a finding that (1) Due to
compelling factors (which may include economic factors such as
qualification of the PWS as serving a disadvantaged community), the PWS
is unable to comply with the requirement or implement measures to
develop an alternative source of water supply; (2) the PWS was in
operation on the effective date of the treatment technique requirement,
or for a PWS that was not in operation by that date, no reasonable
alternative source of drinking water is available to the new PWS; (3)
the exemption will not result in an unreasonable risk to health; and
(4) management or restructuring changes (or both) cannot reasonably
result in compliance with the Act or improve the quality of drinking water.
EPA believes that granting an exemption to the Cryptosporidium
treatment requirements of the LT2ESWTR would result in an unreasonable
risk to health. As described in section III.C, Cryptosporidium causes
acute health effects, which may be severe in sensitive subpopulations
and include risk of mortality. Moreover, the additional Cryptosporidium
treatment requirements of the LT2ESWTR are targeted to PWSs with the
highest degree of risk. Due to these factors, EPA does not support the
granting exemptions from the LT2ESWTR.

V. State Implementation

A. Today's Rule

This section describes the regulations and other procedures and
policies States must adopt to implement today's rule. States must
continue to meet all other conditions of primacy in 40 CFR Part 142. To
implement the LT2ESWTR, States must adopt revisions to the following
sections:

Sec. 141.2--Definitions
Subpart Q--Public Notification
New Subpart W--Additional treatment technique requirements for
Cryptosporidium
Sec. 142.14--Records kept by States
Sec. 142.15--Reports by States
Sec. 142.16--Special primacy requirements
1. Special State primacy requirements
To ensure that a State program includes all the elements necessary
for an effective and enforceable program under today's rule, a State
primacy application must include a description of how the State will
perform the following:
? Approve an alternative to the E. coli levels that trigger
Cryptosporidium monitoring by filtered systems serving fewer than
10,000 people (see section IV.A.1);
? Approve watershed control programs for the 0.5 log
watershed control program credit in the microbial toolbox (see section
IV.D.2);
? Assess significant changes in the watershed and source
water as part of the sanitary survey process and determine appropriate
follow-up action (see section IV.A); and
? Approve protocols for treatment credit under the
Demonstration of Performance toolbox option (see section IV.D.9), for
site specific chlorine dioxide and ozone CT tables (see section
IV.D.14), and for alternative UV reactor validation testing (see
section IV.D.15).
A State program can be more, but not less, stringent than Federal
regulations. As such, some of the elements listed here may not be
applicable to a specific State program.
2. State Recordkeeping Requirements
Today's rule requires States to keep additional records of the
following, including all supporting information and an explanation of
the technical basis for each decision:
? Results of source water E. coli and Cryptosporidium
monitoring for not less than 1 year;
? Cryptosporidium treatment bin classification for each
filtered PWS after the initial and after the second round of source
water monitoring. Also, any change in treatment requirements for
filtered systems due to watershed assessment during sanitary surveys;
? Determination of whether each unfiltered PWS has a mean
source water Cryptosporidium level above 0.01 oocysts/L after the
initial and after the second round of source water monitoring;
? The treatment processes or control measures that each PWS
employs to meet Cryptosporidium treatment requirements under the
LT2ESWTR, including measures that systems may use for only part of the
year; and
? A list of PWSs required to cover or treat the effluent of
an uncovered finished water storage facilities.
3. State Reporting Requirements
Today's rule requires States to report the following information:
? The Cryptosporidium treatment bin classification for each
filtered PWS after the initial and after the second round of source
water monitoring. Also, any change in treatment requirements for
filtered systems due to watershed assessment during sanitary surveys;
and
? The determination of whether each unfiltered PWS has a
mean source water Cryptosporidium level above 0.01 oocysts/L after the
initial and after the second round of source water monitoring.
4. Interim Primacy
States that have primacy (including interim primacy) for every
existing NPDWR already in effect may obtain interim primacy for this
rule, beginning on the date that the State submits the application for
this rule to USEPA, or the effective date of its revised regulations,
whichever is later. A State that wishes to obtain interim primacy

[[Page 730]]

for future NPDWRs must obtain primacy for today's rule. As described in
Section IV.A, EPA expects to work with States to oversee the initial
source water monitoring that begins six months following rule promulgation.

B. Background and Analysis

SDWA establishes requirements that a State or eligible Indian Tribe
must meet to assume and maintain primary enforcement responsibility
(primacy) for its PWSs. These requirements include the following
activities: (1) Adopting drinking water regulations that are no less
stringent than Federal drinking water regulations; (2) adopting and
implementing adequate procedures for enforcement; (3) keeping records
and making reports available on activities that EPA requires by
regulation; (4) issuing variances and exemptions (if allowed by the
State), under conditions no less stringent than allowed under SDWA; and
(5) adopting and being capable of implementing an adequate plan for the
provisions of safe drinking water under emergency situations.
40 CFR part 142 sets out the specific program implementation
requirements for States to obtain primacy for the public water supply
supervision program as authorized under SDWA section 1413. In addition
to adopting basic primacy requirements specified in 40 CFR Part 142,
States may be required to adopt special primacy provisions pertaining
to specific regulations where implementation of the rule involves
activities beyond general primacy provisions. States must include these
regulation specific provisions in an application for approval of their
program revision.
The current regulations in 40 CFR 142.14 require States with
primacy to keep various records, including the following: analytical
results to determine compliance with MCLs, MRDLs, and treatment
technique requirements; PWS inventories; State approvals; enforcement
actions; and the issuance of variances and exemptions. Today's final
rule requires States to keep additional records, including all
supporting information and an explanation of the technical basis for
decisions made by the State regarding today's rule requirements. EPA
currently requires in 40 CFR 142.15 that States report to EPA
information such as violations, variance and exemption status, and
enforcement actions, and today's rule adds additional reporting
requirements related to monitoring and treatment requirements.
On April 28, 1998, EPA amended its State primacy regulations at 40
CFR 142.12 to incorporate the new process identified in the 1996 SDWA
Amendments for granting primary enforcement authority to States while
their applications to modify their primacy programs are under review
(63 FR 23362, April 28, 1998) (USEPA 1998c). The new process grants
interim primary enforcement authority for a new or revised regulation
during the period in which EPA is making a determination with regard to
primacy for that new or revised regulation. This interim enforcement
authority begins on the date of the primacy application submission or
the effective date of the new or revised State regulation, whichever is
later, and ends when EPA makes a final determination. However, this
interim primacy authority is only available to a State that has primacy
(including interim primacy) for every existing NPDWR in effect when the
new regulation is promulgated. States that have primacy for every
existing NPDWR already in effect may obtain interim primacy for this
rule and a State that wishes to obtain interim primacy for future
NPDWRs must obtain primacy for this rule.

C. Summary of Major Comments

Public comment generally supported the special primacy requirements
in the August 11, 2003 proposal, and many commenters expressed
appreciation for the flexibility the special primacy requirements
provided to States. One commenter expressed concern that a State that
adopted this rule by reference would lose the flexibility intended in
the proposal. In response, EPA recognizes that some States may be
limited by their statutes in applying the flexibility allowed under
today's rule. However, EPA believes that providing flexibility for
States to approve site-specific approaches that achieve the public
health goals of the LT2ESWTR is appropriate and will benefit some
States and PWSs.
A few commenters were concerned that the special primacy
requirement to assess changes in watersheds as part of the sanitary
survey process would be difficult to meet due to a lack of resources or
large watersheds that overlap State boundaries. In response, EPA notes
that States are required to evaluate PWS sources under the existing
sanitary survey requirements (40 CFR 142.16(b)(3)). If a State
determines during a sanitary survey that significant changes have
occurred in the watershed that could lead to increased contamination of
the source by Cryptosporidium, today's rule gives the State the
authority to require the PWS to take actions to mitigate or treat the
contamination. Because the treatment requirements in today's rule
depend on the degree of source water contamination, EPA believes that
this assessment of changes in a PWS's source water following initial
bin classification is necessary.
EPA also received comments on State approval processes for
laboratories analyzing for Cryptosporidium to meet LT2ESWTR
requirements. Most commenters stated that EPA should maintain a
national certification program for laboratories approved for
Cryptosporidium analysis for LT2ESTWR compliance. Commenters indicated
that requiring States to approve laboratories for Cryptosporidium
analysis placed too great a demand on State resources. Today's rule
does not include a State primacy requirement for laboratory
certification for Cryptosporidium analysis.
Some commenters were concerned with the data tracking and review
burden on States from the reporting requirements for the individual
toolbox components. EPA agrees with commenters that, in some cases,
allowing PWSs to report summaries or to self-certify that the PWS met
the performance requirements for microbial toolbox treatment credit may
be appropriate. Today's rule allow States to modify the level of
reporting required for toolbox components and specifically, permit PWSs
to self-certify to the State that a toolbox component has met its
performance requirements.

VI. Economic Analysis

This section summarizes the economic analysis (EA) for the final
LT2ESWTR. The EA is an assessment of the benefits, both health and
nonhealth-related, and costs to the regulated community of the final
regulation, along with those of regulatory alternatives that the Agency
considered. EPA developed the EA to meet the requirement of SDWA
section 1412(b)(3)(C) for a Health Risk Reduction and Cost Analysis
(HRRCA), as well as the requirements of Executive Order 12866,
Regulatory Planning and Review, under which EPA must estimate the costs
and benefits of the LT2ESWTR. The full EA is presented in Economic
Analysis for the Long Term 2 Enhanced Surface Water Treatment Rule
(USEPA 2005a), which includes additional details and discussion on the
topics presented throughout this section of the preamble.
The LT2ESWTR is the second in a staged set of rules that address
public health risks from microbial contamination of surface and GWUDI
drinking water supplies and, more specifically, prevent Cryptosporidium

[[Page 731]]

from reaching consumers. As described in section III, EPA promulgated
the IESWTR and LT1ESWTR to provide a baseline of protection against
Cryptosporidium in large and small PWSs, respectively. Today's final
rule will achieve further reductions in Cryptosporidium exposure for
PWSs with the highest vulnerability. This EA considers only the
incremental reduction in exposure beyond the two previously promulgated
rules (IESWTR and LT1ESWTR) from the alternatives evaluated for the
LT2ESWTR.

A. What Regulatory Alternatives Did the Agency Consider?

Regulatory alternatives considered by the Agency for the LT2ESWTR
were developed through the deliberations of the Stage 2 M-DBP Federal
Advisory Committee (described in section III). The Advisory Committee
considered several general approaches for reducing the risk from
Cryptosporidium in drinking water. These approaches included both
additional treatment requirements for all PWSs and risk-targeted
treatment requirements for PWSs with the highest vulnerability to
Cryptosporidium following implementation of the IESWTR and LT1ESWTR. In
addition, the Advisory Committee considered related issues such as
alternative monitoring strategies.
After considering these general approaches, the Advisory Committee
focused on four regulatory alternatives for filtered PWSs (see Table
VI.A-1). With the exception of Alternative 1, which requires all PWSs
to provide additional treatment for Cryptosporidium, these alternatives
incorporate a risk-targeting approach in which PWSs are classified in
different treatment bins based on the results of source water
monitoring. Additional Cryptosporidium treatment requirements are
directly linked to the treatment bin classification. Accordingly, these
rule alternatives are differentiated by two criteria: (1) The
Cryptosporidium concentrations that define the bin boundaries and (2)
the degree of treatment required for each bin.
The Advisory Committee reached consensus regarding additional
treatment requirements for unfiltered PWSs without formally identifying
regulatory alternatives other than requiring no treatment for
Cryptosporidium (i.e., no new regulation).

Table VI.A-1.--Summary of Regulatory Alternatives for Filtered PWSs
------------------------------------------------------------------------
Mean source water Cryptosporidium Additional treatment
monitoring result (oocysts/L) requirements \1\
------------------------------------------------------------------------
Alternative A1
------------------------------------------------------------------------
2.0-log inactivation required for all PWSs
------------------------------------------------------------------------
Alternative A2
------------------------------------------------------------------------
< 0.03.................................... No additional treatment.
>= 0.03 and < 0.1......................... 0.5-log.
>= 0.1 and < 1.0.......................... 1.5-log.
>= 1.0.................................... 2.5-log.
-------------------------------------------
Alternative A3--Today's Final Rule
------------------------------------------------------------------------
< 0.075................................... No additional treatment.
>= 0.075 and < 1.0........................ 1-log.
>= 1.0 and < 3.0.......................... 2-log.
>= 3.0.................................... 2.5-log.
-------------------------------------------
Alternative A4
------------------------------------------------------------------------
< 0.1..................................... No additional treatment.
>= 0.1 and < 1.0.......................... 0.5-log.
>=1.0..................................... 1.0-log.
------------------------------------------------------------------------
\1\ Note: ``Additional treatment requirements'' are in addition to
levels already required under existing rules (e.g., the IESWTR and
LT1ESWTR) for PWSs using conventional treatment or equivalent.

B. What Analyses Support Today's Final Rule?

EPA has quantified benefits and costs for each of the filtered PWS
regulatory alternatives in Table VI.A-1 and for unfiltered PWS
requirements. Quantified benefits stem from estimated reductions in the
incidence of cryptosporidiosis resulting from the regulation. To make
these estimates, the Agency employed Monte Carlo modeling to account
for uncertainty and variability in key parameters like Cryptosporidium
occurrence, infectivity, and treatment efficiency. Costs result largely
from the installation of additional treatment, with lesser costs due to
monitoring and other implementation activities.
Cryptosporidium occurrence significantly influences the estimated
benefits and costs of regulatory alternatives. As discussed in section
III.E, EPA analyzed data collected under the ICR, the ICR Supplemental
Surveys of medium PWSs (ICRSSM), and the ICR Supplemental Surveys of
large PWSs (ICRSSL) to estimate the national occurrence distribution of
Cryptosporidium in surface water. EPA evaluated these distributions
independently when assessing benefits and costs for different
regulatory alternatives.
Another parameter that significantly influences estimated benefits
is Cryptosporidium infectivity (i.e., the likelihood of infection after
exposure to a given dose of Cryptosporidium). As discussed in section
III.E, EPA considered results from human volunteer feeding studies and
applied six different model forms to estimate dose-response relationships.
To address uncertainty in these estimates, benefits are presented
for three different dose response models: A ``high'' estimate based on
the model that showed the highest mean baseline risk, a ``medium''
estimate based on the model and data used at proposal, which is in the
middle of the range of estimates produced by the six models, and a
``low'' estimate, based on the model that showed the lowest mean
baseline risk. These estimates are not upper and lower bounds. For each
model, a distribution of effects is estimated, and the ``high'' and
``low'' estimates show only the means of these distributions for two
different model choices.
Both benefits and costs are determined as annualized present
values, which allows comparison of cost and benefit streams that are
variable over time. The time frame used for both benefit and cost
comparisons is 25 years. The Agency uses social discount rates of both
3 percent and 7 percent to calculate present values from the stream of
benefits and costs and also to annualize the present value estimates
over 25 years (see EPA's Guidelines for Preparing Economic Analyses
(USEPA 2000c) for a discussion of social discount rates).
Results of these analyses are summarized in this section of the
preamble. Detailed results and descriptions of the supporting analyzes
are shown in the LT2ESWTR EA (USEPA 2005a).
In evaluating the regulatory alternatives shown in Table VI.A-1,
EPA and the Advisory Committee were concerned with the following
questions: (1) Do the treatment requirements adequately control
Cryptosporidium concentrations in finished water? (2) How many PWSs
will be required to add treatment? and (3) What is the likelihood that
PWSs will be misclassified in higher or lower treatment bins through
monitoring?
Consistent with the consensus recommendation of the Advisory
Committee, EPA selected Alternative A3 for today's final rule. EPA has
determined that this alternative will significantly reduce the
incidence of cryptosporidiosis due to drinking water

[[Page 732]]

in vulnerable PWSs and is feasible for PWSs to implement.
Alternative A1 (across-the-board 2-log inactivation) was not
selected because it would impose costs but provide few benefits to PWSs
with relatively low Cryptosporidium risk. EPA was also concerned about
the feasibility of requiring every surface water treatment plant to
install additional treatment processes (e.g., UV) for Cryptosporidium.
With Alternative A2, EPA was concerned with the feasibility of
accurately classifying PWSs in treatment bins at a Cryptosporidium
concentration of 0.03 oocysts/L. EPA does not believe that Alternative
A4 would reduce risks from Cryptosporidium in vulnerable PWSs to the
extent feasible, as required under SDWA section 1412(b)(7)(A), because
of the low levels of treatment required.

C. What Are the Benefits of the LT2ESWTR?

EPA has quantified and monetized health benefits for reductions in
endemic cryptosporidiosis due to the LT2ESWTR. In addition, today's
rule is expected to provide additional health and nonhealth-related
benefits that EPA was unable to quantify. Table VI.C-1 summarizes these
unquantified benefits.
1. Nonquantified Benefits

Table VI.C-1.--Summary of Nonquantified Benefits
----------------------------------------------------------------------------------------------------------------
Benefit type Potential effect on benefits Comments
----------------------------------------------------------------------------------------------------------------
Reducing outbreak risks and response Increase............................. Some human or equipment
costs. failures may occur even with
the requirements of today's
rule; however, by adding
barriers of protection for
some PWSs, the rule will
reduce the possibility of such
failures leading to outbreaks.
Reducing averting behavior (e.g., Increase/No Change................... Consumers in PWSs that cease
boiling tap water or purchasing bottled using uncovered finished water
water). reservoirs (through covering
or taking such reservoirs off-
line) may have greater
confidence in water quality.
This may result in less
averting behavior that reduces
both out-of-pocket costs
(e.g., purchase of bottled
water) and opportunity costs
(e.g., time to boil water).
Improving aesthetic water quality....... Increase............................. Some technologies installed for
this rule (e.g., ozone) are
likely to reduce taste and
odor problems.
Reducing risk from co-occurring and Increase............................. Although focused on removal of
emerging pathogens. Cryptosporidium from drinking
water, PWSs that change
treatment processes will also
increase removal of pathogens
that the rule does not
specifically regulate.
Increased source water monitoring....... Increase............................. The greater understanding of
source water quality that
results from monitoring may
enhance the ability of plants
to optimize treatment
operations in ways other than
those addressed in this rule.
Reduced contamination due to covering or Increase............................. Contaminants introduced through
treating finished water storage uncovered finished water
facilities. storage facilities will be
reduced, which will produce
positive public health
benefits.
Change in the levels of disinfection Increase/Decrease.................... PWSs that install ozone to
byproducts. comply with the LT2ESWTR may
experience an increase in
certain DBPs. PWSs that
install UV or microfiltration
may reduce the use of chlorine
and experience a decrease in
DBPs.
----------------------------------------------------------------------------------------------------------------
Source: Chapter 5 of the LT2ESWTR Economic Analysis (USEPA 2005a).

2. Quantified Benefits
In quantifying benefits for the LT2ESWTR based on reductions in the
risk of endemic cryptosporidiosis, EPA considered several categories of
monetized benefits. First, EPA estimated the number of cases expected
to result in premature mortality (primarily for members of sensitive
subpopulations such as AIDS patients). The mortality estimate was
developed using data from the Milwaukee cryptosporidiosis outbreak of
1993 (described in section III), with adjustments to account for the
subsequent decrease in the mortality rate among people with AIDS and
for the difference between the portion of people living with AIDS in
1993 in Milwaukee and the current and projected national levels. EPA
estimated a mortality rate of 26.3 deaths per 100,000 illnesses for
those served by unfiltered PWSs and a mortality rate of 16.7 deaths per
100,000 illnesses for those served by filtered PWSs. These different
rates are associated with the incidence of AIDS in populations served
by unfiltered and filtered PWSs. A complete discussion on how EPA
derived these rates can be found in subchapter 5.2 of the LT2ESWTR EA
(USEPA 2005a).
Reductions in mortalities were monetized using EPA's standard
methodology for monetizing mortality risk reduction. This methodology
is based on a distribution of value of statistical life (VSL) estimates
from 26 labor market and stated preference studies. The mean VSL is
$7.4 million in 2005 with a 5th to 95th percentile range of $1.2 to
$16.9 million. A more detailed discussion of these studies and the VSL
estimate can be found in EPA's Guidelines for Preparing Economic
Analyses (USEPA 2000c). A real income growth factor was applied to
these estimates of approximately 1.9 percent per year for the 20-year
time span following implementation. Income elasticity for VSL was
estimated as a triangular distribution that ranged from 0.08 to 1.00,
with a mode of 0.40. VSL values for the 20-year span are shown in the
LT2ESWTR EA in Exhibit 5.24 (USEPA 2005a).
The substantial majority of cases are not expected to be fatal and
the Agency separately estimated the value of non-fatal illnesses
avoided that would result from the LT2ESWTR. For these, EPA first
divided projected cases into three categories, mild, moderate, and
severe, and then calculated a monetized value per case avoided for each
severity level. These were then combined into a weighted average value
per case based on the relative frequency of each severity level.
According to a study conducted by Corso et al. (2003), the majority of
illness fall into the mild category (88 percent). Approximately 11
percent of illness fall into the moderate category, which is defined as
those who seek medical treatment but are not hospitalized. The final 1
percent have severe symptoms that result in hospitalization. EPA
estimated different medical expenses and time losses for each category.
Benefits for non-fatal cases were calculated using a cost-of-
illness (COI)

[[Page 733]]

approach. Traditional COI valuations focus on medical costs and lost
wages, and leave out significant categories of benefits, specifically
the reduced utility from being sick (i.e., lost personal or non-work
time, including activities such as child care, homemaking, community
service, time spent with family, recreation, and pain and suffering),
although some COI studies also include an estimate for unpaid labor
(household production) valued at an estimated wage rate designed to
reflect the market value of such labor (e.g., median wage for household
domestic labor). Ideally, a comprehensive willingness to pay (WTP)
estimate would be used that includes all categories of loss in a single
number. However, a review of the literature indicated that the
available studies were not suitable for valuing cryptosporidiosis;
hence, estimates from this literature are inappropriate for use in this
analysis. Instead, EPA presents two COI estimates: A traditional
approach that only includes valuation for medical costs and lost work
time (including some portion of unpaid household production); and an
enhanced approach that also factors in valuations for lost unpaid work
time for employed people, reduced utility (or sense of well-being)
associated with decreased enjoyment of time spent in non-work
activities, and lost productivity at work on days when paid workers are
ill but go to work anyway.
Table VI.C-2 shows the various categories of loss and how they were
valued for each estimate for a ``typical'' case in 2003 (weighted
average based on severity level).

Table VI.C-2.--Traditional and Enhanced COI for Cryptosporidiosis, 2003$
[Weighted average cost per case]
------------------------------------------------------------------------
Loss category Traditional COI Enhanced COI
------------------------------------------------------------------------
Direct Medical Costs............. $106.91 106.91
Lost Paid Work Days.............. 120.13 120.13
Lost Unpaid Work Days \1\........ 24.32 48.64
Lost Leisure Time \2\............ not included 217.79
Lost Caregiver Days \3\.......... 22.98 61.50
Lost Leisure Productivity \4\.... not included 162.98
Lost Productivity at Work........ not included 126.29
----------------------------------
Total........................ 274.34 844.24
------------------------------------------------------------------------
\1\ Assigned to 39.7% of the population not engaged in market work;
assumes 40 hr. unpaid work week, valued at $6.23/hr in traditional COI
and $12.46/hr in enhanced COI. Does not include lost unpaid work for
employed people and may not include all unpaid work for people outside
the paid labor force.
\2\ Includes child care and homemaking (to the extent not covered in
lost unpaid work days above), time with family, and recreation for
people within and outside the paid labor force, on days when subject
is too sick to work.
\3\ Values lost work or leisure time for people caring for the ill.
Traditional approach does not include lost leisure time. Detail may
not calculate to totals due to independent rounding; Source: Appendix
L in LT2ESWTR EA (USEPA 2005a)
\4\ Analogous to lost productivity at work. Includes reduced
productivity in unpaid work and reduced enjoyment of recreation on
days when subject is sick but engages in unpaid work or leisure
activities anyway.

The various loss categories were calculated as follows: Medical
costs are a weighted average across the three illness severity levels
of actual costs for doctor and emergency room visits, medication, and
hospital stays. Lost paid work represents missed work time of paid
employees, valued at the median pre-tax wage, plus benefits, of $20.82
hour. The average number of lost work hours per illness day is 3.4
(this assumes that 60 percent of the population is in the paid labor
force and the loss is averaged over 7 days). The weighted average
number of lost work days per case is 1.7 days. Medical costs and lost
work days reflect market transactions. Medical costs are always
included in COI estimates and lost work days are usually included in
COI estimates.
In the traditional COI estimate, an equivalent amount of lost
unpaid work time was assigned to the 40 percent of the population that
are not in the paid labor force. This includes homemakers, students,
children, retires, and unemployed persons. This estimate attempts to
capture market-like work (e.g., homemaking, volunteer work) that is
unpaid. EPA did not attempt to calculate what percent of cases falls in
each of these five groups, or how many hours per week each group works,
but rather assumed an across-the-board 40 hour unpaid work week. For
this reason, it likely overstates the value of unpaid, market-like
work, but EPA does not have data on this. This time is valued at $6.23
per hour, which is one half the median post-tax wage (since work
performed by these groups is not taxed). This is also approximately the
median wage for paid household domestic labor.
In the enhanced COI estimate, an estimate of lost unpaid work days
for people outside the paid labor force was made by assigning the value
of $12.46 per hour to the same number of unpaid work hours valued in
the traditional COI approach (i.e., 40 unpaid work hours per week).
Lost unpaid work for employed people and any unpaid labor beyond 40
hours per week for those not in the labor market is shown as lost
leisure time in Table VI.C-2 for the enhanced approach and is not
included in the traditional approach.
In the enhanced approach, all time other than paid and market-like
work and sleep (8 hours per work day and 16 hours per non-work day) is
valued at the median after tax wage, or $12.46 per hour. This includes
lost unpaid personal work (e.g., chores, errands, housework) and
leisure time for people within and outside the paid labor force. The
average number of unpaid work hours per illness day is 2.3 (40 hours
per week averaged over 7 days x 40 percent of the population). Implicit
in this approach is that people would pay the same amount not to be
sick during their leisure time as they require to give up their leisure
time to work (i.e., the after tax wage). In reality, people might be
willing to pay either more than this amount (if they were very sick and
suffering a lot) or less than this amount (if they were not very sick
and still got some enjoyment out of activities such as resting,
reading, and watching TV), not to be sick. Multiplying 10.3 hours by
$12.46 gives a value of about $128 for a day of ``lost'' unpaid
personal work and leisure (i.e., lost utility of being sick). The
weighted average number of lost leisure days per case is the same as
the weighted average number of lost work days (1.7 days per case).

[[Page 734]]

In addition, for days when an individual is well enough to work but
is still experiencing symptoms, such as diarrhea, the enhanced estimate
also includes a 30 percent loss of work and leisure productivity, based
on a study of giardiasis illness (Harrington et al. 1985), which is
similar to cryptosporidiosis. Appendix P in the EA describes similar
productivity losses for other illnesses such as influenza (35%-73%
productivity losses). In the traditional COI analysis, productivity
losses are not included for either work or nonwork time. The weighted
average number of reduced productivity days per case, for both work and
leisure, is 1.3 days.
EPA believes that losses in productivity and lost leisure time are
unquestionably present and that these categories have positive value;
consequently, the traditional COI estimate understates the true value
of these loss categories. EPA notes that these estimates should not be
regarded as upper and lower bounds. In particular, the enhanced COI
estimate may not fully incorporate the value of pain and suffering, as
people may be willing to pay more than $228 (the sum of the valuation
of lost work and leisure) to avoid a day of illness. The traditional
COI estimate may not be a lower bound because it includes a valuation
for a lost 40 hour work week for all persons not in the labor force,
including children and retirees. This may be an overstatement of lost
productivity for these groups, which would depend on the impact of such
things as missed school work or volunteer activities that may be
affected by illness.
As with the avoided mortality valuation, the real wages used in the
COI estimates were increased by a real income growth factor that varies
by year, but is the equivalent of about 1.9 percent over the 20 year
period. This approach of adjusting for real income growth was
recommended by the SAB (USEPA 2000d) because the median real wage is
expected to grow each year (by approximately 1.9 percent).
Correspondingly, the real income growth factor of the COI estimates
increases by the equivalent of 1.9 percent per year (except for medical
costs, which are not directly tied to wages). This approach gives a
total COI valuation per case in 2010 of $306 (undiscounted) for the
traditional COI estimate and $985 (undiscounted) for the enhanced COI
estimate; the valuation in 2029 is $381 (undiscounted) for the
traditional COI estimate and $1,316 (undiscounted) for the enhanced COI
estimate. There is no difference in the methodology for calculating the
COI over this 20 year period of implementation; the change in valuation
is due to the underlying change in projected real wages.
Table VI.C-3 summarizes the annual cases of cryptosporidiosis
illness and associated deaths avoided due to the LT2ESWTR proposal.
Today's rule, on average, is expected to reduce 89,375 to 1,459,126
illnesses and 20 to 314 deaths annually after full implementation
(range based on the ICRSSL, ICRSSM, and ICR data sets and model choice
for Cryptosporidium infectivity).
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.001

Tables VI.C-4a and VI.C-4b show the monetized present value of the
benefit for reductions in endemic cryptosporidiosis estimated to result
from the LT2ESWTR for the enhanced and traditional COI values,
respectively. Estimates are given for the ICR, ICRSSL, and ICRSSM
occurrence data sets and for the three infectivity models.
With the enhanced COI and a 3 percent discount rate, the annual
present value of the mean benefit estimate ranges from $177 million to
$2.8 billion; at a 7 percent discount rate, the mean estimate ranges
from $144 million to $2.3 billion. With the traditional COI, the
corresponding mean benefit estimate at a 3 percent discount rate ranges
from $130 million to $2.0 billion; for a 7 percent discount rate, the
mean estimate ranges from $105 million to $1.7 billion. None of these
values include the unquantified and nonmonetized benefits listed in
Table VI.C-1.
BILLING CODE 6560-50-P

[[Page 735]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.002

BILLING CODE 6560-50-C
a. Filtered PWSs. Benefits to the approximately 168 million people
served by filtered surface water and GWUDI PWSs range from 34,000 to
702,000 reduction in mean annual cases of endemic illness based on
three infectivity models and ICRSSL, ICRSSM, and ICR data sets. In
addition, premature mortality is expected to be reduced by an average
of 6 to 116 deaths annually.
b. Unfiltered PWSs. The 10 million people served by unfiltered
surface water or GWUDI PWSs will see a significant reduction in
cryptosporidiosis as a result of the LT2ESWTR. In this population, the
rule is expected to reduce approximately 55,000 to 758,000 cases of
illness and 14 to 197 premature deaths annually.
For unfiltered PWSs, only the ICR data set is used to directly
calculate illness reduction because it is the only data set that
includes sufficient information on unfiltered PWSs. Illness reduction
in unfiltered PWSs was estimated for the ICRSSL and ICRSSM

[[Page 736]]

data sets by multiplying the ICR unfiltered PWS result by the ratio,
for the quantity estimated, between filtered PWS results from the
supplemental survey data set (SSM or SSL) and filtered PWS results from
the ICR.
3. Timing of Benefits Accrual (latency)
In previous rulemakings, some commenters have argued that the
Agency should consider an assumed time lag or latency period in its
benefits calculations. The Agency has not conducted a latency analysis
for this rule because cryptosporidiosis is an acute illness; therefore,
very little time elapses between exposure, illness, and mortality.
However, EPA does account for benefits and costs that occur in future
years by converting these to present value estimates.

D. What Are the Costs of the LT2ESWTR?

In order to estimate the costs of today's rule, the Agency
considered impacts on PWSs and on States (including territories and EPA
implementation in non-primacy States). Summary information on these
costs follows, with more detailed information in chapter 6 of the
LT2ESWTR EA (USEPA 2005a). A detailed discussion of the requirements of
today's rule is located in section IV of this preamble.
1. Total Annualized Present Value Costs
Tables VI.D-1 summarizes the annualized present value cost
estimates for the LT2ESWTR at 3 percent and 7 percent discount rates.
The mean annualized present value costs of the LT2ESWTR are estimated
to range from approximately $93 to $133 million using a 3 percent
discount rate and $107 to $150 million using a 7 percent discount rate.
This range in mean cost estimates is associated with the different
Cryptosporidium occurrence data sets. In addition to mean estimates of
costs, the Agency calculated 90 percent confidence bounds by
considering the uncertainty in Cryptosporidium occurrence estimates and
the uncertainty around the mean unit technology costs (USEPA 2005a).
PWSs will incur approximately 99 percent of the rule's total
annualized present value costs. States incur the remaining rule costs.
Table VI.D-2 shows the undiscounted initial capital and one-time costs
broken out by rule component. A comparison of annualized present value
costs among the rule alternatives considered by the Agency is located
in section VI.F of this preamble.
BILLING CODE 6560-50-P

[[Page 737]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.003
[[Page 738]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.004
BILLING CODE 6560-50-C
[[Page 739]]

2. PWS Costs
Table VI.D-3 shows the number of filtered and unfiltered PWSs that
will incur costs by rule provision. All PWSs that treat surface water
or GWUDI (i.e., nonpurchased PWSs) will incur one-time costs that
include time for staff training on rule requirements. PWSs will incur
monitoring costs to assess source water Cryptosporidium levels, though
monitoring requirements vary by PWS size (large vs. small) and PWS type
(filtered vs. unfiltered). Some PWSs will incur costs for additional
Cryptosporidium treatment, where required, and for covering or treating
uncovered finished water reservoirs.
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.005

a. Source water monitoring costs. Source water monitoring costs are
structured on a per-plant basis. There are three types of monitoring
that plants may be required to conduct--turbidity, E. coli, and
Cryptosporidium. Source water turbidity is a common water quality
parameter used for plant operational control. Also, to meet SWTR,
LT1ESWTR, and IESWTR requirements, most PWSs have turbidity analytical
equipment in-house and operators are experienced with turbidity
measurement. Thus, EPA assumes that the incremental turbidity
monitoring burden associated with the LT2ESWTR is negligible.
Filtered plants in small PWSs initially will be required to conduct
1 year of biweekly E. coli source water monitoring. These plants will
be required to monitor for Cryptosporidium if E. coli levels exceed 10
E. coli/100 mL for lakes and reservoir sources or 50 E. coli/100 mL for
flowing stream sources. EPA estimated the percent of small plants that
would be triggered into Cryptosporidium monitoring as being equal to
the percent of large plants that would fall into any bin requiring
additional treatment.
Estimates of laboratory fees, shipping costs, labor hours for
sample collection, and hours for reporting results were used to predict
PWS costs for initial source water monitoring under the LT2ESWTR. Table
VI.D-4 summarizes the present value of monitoring costs for initial bin
classification. Total present value monitoring costs for initial bin
classification range from $45 million to $59 million depending on the
occurrence data set and discount rate. Appendix D of the LT2ESWTR EA
provides a full explanation of how these costs were developed (USEPA
2005a).
b. Filtered PWSs treatment costs. The Agency calculated treatment
costs by estimating the number of plants that will add treatment
technologies and coupling these estimates with unit costs ($/plant) of
the selected technologies. Table VI.D-5 shows the number of plants
estimated to select different treatment technologies; Table VI.D-6
summarizes the present value treatment costs and annualized present
value costs for both filtered and unfiltered PWSs.

[[Page 740]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.006

To estimate the number of filtered plants that would select a
particular treatment technology, EPA followed a two step process.
First, the number of plants that will be assigned to treatment bins
requiring additional treatment was estimated. Second, the treatment
technologies that plants will choose to meet these requirements was
estimated using a ``least-cost decision tree.'' In this estimate, EPA
assumed that PWSs will select the least expensive technology or
combination of technologies to meet the log removal requirements of a
given treatment bin. Technology selections were constrained by maximum
use percentages, which recognize that some plants will not be able to
implement certain technologies because of site-specific conditions. In
addition, certain potentially lower cost components of the microbial
toolbox, such as changes to the plant intake, were not included because
EPA lacked data to estimate the number of plants that could select it.
These limitations on technology use may result in an overestimate of
costs. An in-depth discussion of the technology selection methodology
and unit cost estimates can be found in Appendices E and F of the
LT2ESWTR EA (USEPA 2005a).
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.007

c. Unfiltered PWSs treatment costs. The LT2ESWTR requires all
unfiltered PWSs to achieve 2-log of inactivation if their mean source
water Cryptosporidium concentration is less than or equal to 0.01
oocysts/L and 3-log of inactivation if it is greater than 0.01 oocysts/
L. For most PWSs, UV appears to be the least expensive technology that
can achieve these levels of Cryptosporidium inactivation, and EPA
expects UV to be widely used by unfiltered PWSs to meet today's rule
requirements. However, as with filtered PWSs, EPA estimated that a
small percentage of plants would elect to install a technology more
expensive than UV due to the configuration of

[[Page 741]]

existing equipment or other factors. Ozone is the next least expensive
technology that will meet the inactivation requirements for some PWSs
and EPA estimated that it will be used by plants that do not use UV.
All unfiltered PWSs must meet requirements of the LT2ESWTR;
therefore, 100 percent of unfiltered PWSs are estimated to add
technology. This assumes that no unfiltered PWSs currently use these
additional treatment technologies. For this cost analysis, EPA assumed
that all very small unfiltered PWSs will use UV; for all other
unfiltered PWS sizes, EPA estimated that 90 percent will install UV and
10 percent will add ozone. Treatment costs for unfiltered PWSs are
included in Table VI.D-6.
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.008

d. Uncovered finished water storage facilities. As part of the
LT2ESWTR, PWSs with uncovered finished water storage facilities must
either cover the storage facility or treat the discharge to achieve
inactivation and/or removal of at least 2-log Cryptosporidium, 3-log
Giardia lamblia, and 4-log viruses. To develop national cost estimates
for PWSs to comply with these provisions, unit costs for each
compliance alternative and the percentage of PWSs selecting each
alternative were estimated for the inventory of uncovered finished
water storage facilities. From a recent survey of EPA Regions, EPA
estimates that there are currently 81 uncovered finished water storage
facilities for which PWSs must take steps to comply with the LT2ESWTR.
A full description of the unit costs and other assumptions used in this
analysis is presented in Chapter 6 and Appendix I of the LT2ESWTR EA
(USEPA 2005a).
To comply with the treatment requirements, EPA determined that the
least-cost treatment option is a combination of chlorine and UV. For
PWSs with uncovered storage facility capacities of 5 million gallons
(MG) or less, covering the storage facilities is the least expensive
alternative. Although disinfection is the least expensive alternative
for the remaining PWSs, the ability of a PWS to use booster
chlorination depends on their current residual disinfectant type.
Somewhat less than half of all surface water PWSs are predicted to use
chloramination following implementation of the Stage 2 DBPR. Adding
chlorine to water that has been treated with chloramines is not a
feasible alternative; therefore, the fraction of PWSs projected to add
UV and booster chlorination to the effluent from the uncovered storage
facility was estimated at 50 percent, with the remaining 50 percent
projected to add covers.
Table VI.D-7 summarizes total annualized present value costs for
the uncovered finished water storage facility requirements using both 3
and 7 percent discount rates. EPA estimates the total annualized
present value cost for covering or treating the water from uncovered
finished water storage facilities to be approximately $10 million at a
3 percent discount rate and $13 million at a 7 percent discount rate.

[[Page 742]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.009

e. Future monitoring costs. Six years after initial bin
classification, filtered and unfiltered PWSs must conduct a second
round of monitoring to assess whether source water Cryptosporidium
levels have changed significantly. EPA will evaluate new analytical
methods and surrogate indicators of microbial water quality in the
interim. While the costs of monitoring are likely to change in the 9
years following rule promulgation, it is difficult to predict how they
will change. In the absence of any other information, EPA assumed that
the laboratory costs will be the same as for the initial monitoring.
All PWSs that conducted initial monitoring were assumed to conduct
the second round of monitoring, except for those PWSs that installed
treatment that achieves a total of 5.5-log or greater treatment for
Cryptosporidium as a result of the rule. These PWSs are exempt from
monitoring under the LT2ESWTR. EPA estimates that the cost of the
second round of source water monitoring will range from $21 million to
$36 million, depending on the occurrence data set and discount rate
used in the estimate. Appendix D of the EA provides further details
(USEPA 2005a).
f. Sensitivity analysis-influent bromide levels on technology
selection for filtered plants. One concern with the ICR data set is
that it may not reflect influent bromide levels in some PWSs during
droughts. High influent bromide levels (the precursor for bromate
formation) limits ozone use because some PWSs would not be able to meet
the MCL for bromate. EPA conducted a sensitivity analysis to estimate
the impact that higher influent bromide levels would have on technology
decisions. The sensitivity analysis assumed influent bromide
concentrations of 50 parts per billion (ppb) above the ICR
concentrations. Results of the analysis indicate that this higher
bromide level has a minimal impact on costs.
3. State/Primacy Agency Costs
EPA estimates that States (including primacy agencies) will incur
an annualized present value cost of $1.1 to 1.2 million using a 3
percent discount rate and $1.4 million at 7 percent. State
implementation activities include regulation adoption, program
implementation, training State staff, training PWS staff, providing
technical assistance to PWSs, and updating management systems. To
estimate implementation costs to States, the number of full-time
employees (FTEs) per activity is multiplied by the number of labor
hours per FTE, the cost per labor hour, and the number of States and
Territories.
In addition to implementation costs, States will also incur costs
associated with managing monitoring data. Because EPA will directly
manage reporting, approval, and analysis of results from the initial
round of monitoring by large PWSs (serving at least 10,000 people),
States are not predicted to incur costs for these activities. States
will, however, incur costs associated with small PWS monitoring. This
is a result of the later start of small PWS monitoring, which will mean
that some States will assume primacy for small PWS monitoring. In
addition, States will review the second round of monitoring results.
States will also incur costs for reviewing technology compliance data
and consulting with PWSs regarding disinfection benchmarking (for PWSs
that change their disinfection procedures to comply with today's rule).
Appendix D of the LT2ESWTR EA provides more information about the State
cost analysis (USEPA 2005a).
4. Non-Quantified Costs
EPA has quantified all the major costs for this rule and has
provided uncertainty analyses to bound the over or underestimates in
the costs. There are some costs that EPA has not quantified, however,
because of lack of data. For example, some PWSs may merge with
neighboring PWSs to comply with this rule. Such changes have both costs
(legal fees and connecting infrastructure) and benefits (economies of
scale). Likewise, PWSs would incur costs for procuring a new source of
water that may result in lower overall treatment costs.
In addition, the Agency was unable to predict the usage or estimate
the costs of several options in the microbial toolbox. These options
include intake management and demonstrations of performance. They have
not been included in the quantified analysis because data are not
available to estimate the number of PWSs that may use these toolbox
options to comply with the LT2ESWTR. Not including these generally
lower-cost options may result in overestimation of costs.

E. What Are the Household Costs of the LT2ESWTR?

Another way to assess a rule's impact is to consider how it may
impact residential water bills. This analysis considers the potential
increase in a household's water bill if a CWS passed the entire cost
increase resulting from this rule on to its customers. This serves as a
tool to gauge potential impacts and should not be construed as precise
estimates of potential changes to individual water bills.
Included in this analysis are all PWS costs, including rule
implementation, initial and future monitoring for bin classification,
additional Cryptosporidium treatment, and treating

[[Page 743]]

or covering uncovered finished water storage facilities. Costs for
Cryptosporidium monitoring by small PWSs, additional Cryptosporidium
treatment, and uncovered finished water storage facilities are assigned
only to the subset of PWSs expected to incur them. Although
implementation and monitoring represent relatively small, one-time
costs, they have been included in the analysis to provide a complete
distribution of the potential household cost. A detailed description of
the derivation of household costs is in Chapter 6 and Appendix J of the
LT2ESTWR EA (USEPA 2005a).
For PWSs that purchase treated water (i.e., purchased PWSs) from
larger nonpurchased PWSs, the households costs are calculated based on
the unit treatment costs of the larger PWS but included in the
distribution for the size category of the purchased PWS. Households
costs for these purchased PWSs are based on the household usage rates
appropriate for the retail PWS and not the PWS selling (wholesaling)
the water. This approach for purchased PWSs reflects the fact that
although they will not face increased costs from adding their own
treatment, whatever costs the wholesale PWS incurs will likely be
passed on as higher water costs.
Table VI.E-1 shows the results of the household cost analysis. In
addition to mean and median estimates, EPA calculated the 90th and the
95th percentiles. EPA estimates that all households served by surface
and GWUDI sources will face some increase in household costs due to
implementation of the LT2ESWTR. Of all the households subject to the
rule, from 22 to 41 percent are projected to incur costs for adding
treatment, depending on the Cryptosporidium occurrence data set used.
Approximately 92 percent of the households potentially subject to
the rule are served by PWSs serving at least 10,000 people and 99.8
percent are served by PWSs serving at least 500 people; these PWSs
experience the lowest increases in costs due to significant economies
of scale. Over 95 percent of all households are estimated to face an
annual cost increase of less than $12. Households served by small PWSs
that install advanced technologies will face the greatest increases in
annual costs. EPA expects that the model's projections for these PWSs
are, in some cases, overstated. Some PWSs are likely to find
alternative treatment techniques such as other toolbox options not
included in this analysis, or sources of water (ground water, purchased
water, or consolidating with another PWS) that would be less costly
than installing more expensive treatment technologies.
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.010

[[Page 744]]

F. What Are the Incremental Costs and Benefits of the LT2ESWTR?

Incremental costs and benefits are those that are incurred or
realized in reducing Cryptosporidium exposures from one regulatory
alternative to the next. Estimates of incremental costs and benefits
are useful in considering the economic efficiency of different
regulatory alternatives evaluated by EPA. Generally, the goal of an
incremental analysis is to identify the most efficient regulatory
alternative. However, this analysis is incomplete because some benefits
from this rule are unquantified and not monetized. Incremental analyses
should consider both quantified and unquantified (where possible)
benefits and costs.
Usually an incremental analysis implies increasing levels of
stringency along a single parameter, with each alternative providing
all the protection of the previous alternative, plus additional
protection. However, the regulatory alternatives evaluated for the
LT2ESWTR vary by multiple parameters (e.g., treatment bin boundaries,
treatment requirements). The comparison between any two alternatives
is, therefore, between two separate sets of benefits, in the sense that
they may be distributed to somewhat different population groups.
The regulatory alternatives, however, do achieve increasing levels
of benefits at increasing levels of costs. As a result, displaying
incremental net benefits from the baseline and alternative to
alternative is possible. Tables VI.F-1a and VI.F-1b show incremental
costs, benefits, and net benefits for the four regulatory alternatives,
A1-A4, shown in Table VI.A-1, using the enhanced and traditional COI,
respectively. All values are annualized present values expressed in
Year 2003 dollars. The displayed values are the mean estimates for each
occurrence distribution and infectivity model.
With the enhanced COI, incremental costs are generally closest to
incremental benefits for A2, a more stringent alternative than A3,
which is today's final rule. For the traditional COI, incremental costs
most closely equal incremental benefits for A3 under the majority of
conditions evaluated.

G. Are There Benefits From the Reduction of Co-Occurring Contaminants?

While the quantified and monetized benefits for the LT2ESWTR
includes only reductions in illness and mortality attributable to
Cryptosporidium, today's rule will reduce exposure to and disease from
other microbial pathogens and, in some cases, chemical contaminants.

[[Page 745]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.011
[[Page 746]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.012

All of the options in the microbial toolbox that PWSs will
implement to comply with today's rule will also reduce levels of other
microbial pathogens. For example, watershed control programs and intake
relocation

[[Page 747]]

will cut overall pathogen levels by reducing fecal contamination in the
source water. Membrane, bag, and cartridge filters will remove
pathogenic protozoa like Giardia lamblia that are similar in size to or
larger than Cryptosporidium. Lowering finished water turbidity from
conventional and direct filtration will improve removal of pathogens
across a broad size range, including viruses, bacteria, and protozoa.
Inactivation technologies like ozone and UV are highly effective
against a large number of different pathogen types.
Some membrane technologies that PWSs may install to comply with the
LT2ESWTR can also reduce or eliminate chemical contaminants including
arsenic, DBPs, and atrazine. The use of UV for inactivation of
Cryptosporidium may reduce the chlorine dosage that some PWSs must
apply, which can reduce levels of DBPs. EPA has recently finalized a
rule to further control arsenic levels in drinking water and is
concurrently establishing the Stage 2 DBPR to address DBP control.
The extent to which the LT2ESWTR can reduce the overall risk from
other contaminants has not been quantitatively evaluated because EPA
lacks sufficient data on the co-occurrence among Cryptosporidium and
other microbial pathogens and contaminants. Further, due to the
difficulties in establishing which PWSs would have multiple problems,
such as microbial contamination, arsenic, and DBPs or any combination
of the three, no estimate was made of the potential cost savings from
addressing more than one contaminant simultaneously.

H. Are There Increased Risks From Other Contaminants?

It is unlikely that the LT2ESWTR will result in a significant
increase in risk from other contaminants for most PWSs. Many of the
options that PWSs will select to comply with the LT2ESWTR, such as UV,
additional or improved filtration, and watershed control, do not form
DBPs. Ozone, another technology that is effective against
Cryptosporidium, does form DBPs (e.g., bromate). However, bromate is
currently regulated under the Stage 1 DBPR, and PWSs will have to
comply with this regulation if they implement ozone to meet the LT2ESWTR.

I. What Are the Effects of the Contaminant on the General Population
and Groups Within the General Populations That Are Identified as Likely
To be at Greater Risk of Adverse Health Effects?

Section III of this preamble discusses the health effects
associated with Cryptosporidium on the general population as well as
the effects on other sensitive sub-populations. In addition, health
effects associated with children and pregnant women are discussed in
greater detail in section VII.G of this preamble.

J. What Are the Uncertainties in the Risk, Benefit, and Cost Estimates
for the LT2ESWTR?

For today's final rule, EPA has modeled the current baseline risk
from Cryptosporidium exposure through drinking water, along with the
reduction in risk and the cost for various rule alternatives. There is
uncertainty in the risk calculation, the benefit estimates, the cost
estimates, and the interaction with other regulations. The LT2ESWTR EA
has an extensive discussion of relevant uncertainties (USEPA 2005a),
and a brief summary of the major uncertainties follows.
In regard to the risk estimates, the most significant areas of
uncertainty are Cryptosporidium occurrence, treatment, and infectivity.
Among the three available occurrence data sets, the ICR plant-mean data
were higher than the ICRSSM or ICRSSL plant-mean data at the 90th
percentile. The reasons for these differing results are not well
understood but may stem from year-to-year variation in occurrence and
differences in the sampling and measurement methods employed. The
ICRSSM and ICRSSL data sets use a newer, more reliable sampling method
but include fewer plants and a shorter time frame. Additional
uncertainty is associated with estimating finished water occurrence
because the analysis is based on estimates of treatment plant
performance in removing Cryptosporidium.
EPA has addressed some of the uncertainty in occurrence by
evaluating benefits and costs for regulatory alternatives with each
Cryptosporidium data set. Further, in the 2-dimensional Monte Carlo
simulation models used to estimate risk, key parameters like occurrence
and treatment efficiency are treated as both variable and uncertain.
This approach is intended to account for the limitations in available
data and the recognized variability in these parameters among PWSs.
EPA has also considered occurrence data from additional sources.
For example, the LT2ESWTR EA discusses a study of infectious
Cryptosporidium in the finished water of 82 filtration plants by
Aboytes et.al, 2004. The mean level of infectious Cryptosporidium
measured in this study is higher than EPA has estimated using the ICR,
ICRSSM, or ICRSSL data sets. This result suggests that Cryptosporidium
occurrence at these plants may have exceeded levels during the ICR and
ICRSS surveys or that EPA may have overestimated the efficiency of
treatment plants in removing Cryptosporidium.
In regard to Cryptosporidium infectivity, EPA evaluated data from
human feeding studies conducted with different Cryptosporidium
isolates. The measured infectivity of these isolates varied widely,
however, and how well these isolates represent Cryptosporidium that
causes disease in PWSs is uncertain. In addition, extrapolating from
the higher Cryptosporidium dosing levels used in the human feeding
studies to the exposure levels typical for drinking water (e.g., one
oocyst) is uncertain. Another source of uncertainty is differences that
exist among populations groups, such as individuals that are more
sensitive (e.g., children, immunocompromised) or less sensitive
(previously infected adults).
EPA accounted for some of this uncertainty in infectivity by
treating the human feeding study results for different Cryptosporidium
isolates as random samples from a larger and unknown environmental
distribution of Cryptosporidium infectivity. EPA used a variety of
models for this analysis, as recommended by the SAB, and presents
results for a range of models to account for uncertainty in model
selection. In addition, limited data on levels of Cryptosporidium in
the 1993 Milwaukee outbreak and associated disease incidence suggest
that the infectivity of the Cryptosporidium responsible for that
outbreak is within the range EPA has estimated for the risk assessment
in today's rule.
Unquantified benefits from the reduction of co-occurring microbial
pathogens, as described earlier, are a significant source of
uncertainty in the estimate of benefits for the LT2ESWTR. EPA is also
uncertain about the monetization of avoided disease from
Cryptosporidium and has addressed this uncertainty through the use of
both traditional and enhanced COI values for benefits estimates.
While all of the significant costs of today's rule have been
identified by

[[Page 748]]

EPA, there are uncertainties in the estimates. Occurrence is the most
significant source of uncertainty in costs, and EPA has attempted to
account for this uncertainty through the use of different occurrence
data sets and Monte Carlo modeling as described previously. EPA has
also estimated uncertainty in unit process costs for treatment
technologies. In addition, the cost assessment for today's rule
includes sensitivity analyses, such an assessment of the impact of
influent bromide levels on technology selection. Chapter 6 of the
LT2ESWTR EA provides a fuller description of uncertainties in the cost
estimates (USEPA 2005a).
Last, EPA has recently finalized or is currently finalizing new
regulations for arsenic, radon, Cryptosporidium in small surface water
PWSs, filter backwash recycling, microbial pathogens in PWSs using
ground water, and DBPs. These rules may have overlapping impacts on
some PWSs, but the extent is not possible to estimate due to lack of
information on co-occurrence. However, PWSs may choose treatment
technologies that will address multiple contaminants. Therefore, while
the total cost impact of these drinking water rules is uncertain, it is
most likely less than the estimated total cost of all individual rules
combined.

K. What Is the Benefit/Cost Determination for the LT2ESWTR?

The Agency has determined that the benefits of the LT2ESWTR justify
the costs. As discussed in section VII.C, the rule provides a large
reduction in endemic cryptosporidiosis illness and mortalities. More
stringent alternatives provide greater reductions but at higher costs.
Alternative A1 provides the greatest overall reduction in illnesses and
mortalities but the incremental benefits between this option and
alternative A3 (today's final rule) are relatively small while the
incremental costs are significant. In addition, today's rule, unlike
alternative A1, specifically targets those PWSs whose source water
requires higher levels of treatment.
Tables VI.K-1a and VI.K-1b present net benefits for the four
regulatory alternatives that were evaluated. Generally, analysis of net
benefits is used to identify alternatives where benefits exceed costs,
as well as the alternative that maximizes net benefits. However, as
with the analysis of incremental net benefits discussed previously, the
usefulness of this analysis in evaluating regulatory alternatives for
the LT2ESWTR is somewhat limited because many benefits from this rule
are unquantified and nonmonetized. Analyses of net benefits should
consider both quantified and unquantified (where possible) benefits and
costs.
Also, as noted earlier, the regulatory alternatives considered for
the LT2ESWTR vary both in the population that experiences benefits and
costs (i.e., treatment bin boundaries) and the magnitude of the
benefits and costs (i.e., treatment requirements). Consequently, the
more stringent regulatory alternatives provide benefits to population
groups that do not experience any benefit under less stringent
alternatives.
As shown by Tables VI.K-1a and VI.K-1b, net benefits are positive
for all four regulatory alternatives evaluated under most occurrence
and discount rate scenarios. With both the enhanced COI and traditional
COI, net benefits are highest for the alternative A3, which is today's
final rule, under the majority of occurrence distributions and discount
rates evaluated.
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.013

[[Page 749]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.014

In addition to the net benefits of the LT2ESWTR, the Agency used
several other techniques to compare costs and benefits. For example,
EPA calculated the cost of the rule per case avoided. Tables VI.K-2a, b
and c show both the cost of the rule per illness avoided and cost of
the rule per death avoided. This cost effectiveness measure is another
way of examining the benefits and costs of the rule but should not be
used to compare alternatives because an alternative with the lowest
cost per illness/death avoided may not result in the highest net
benefits. With the exception of alternative A1, the rule options look
favorable when the cost per case avoided is compared to both the
weighted cost of cryptosporidiosis illness ($844 and $274 for the two
COI approaches) and the mean value of a statistical death avoided--
approximately $7 million dollars. Additional information about this
analysis and other methods of comparing benefits and costs can be found
in chapter 8 of the LT2ESWTR EA (USEPA 2005a).

[[Page 750]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.015
[[Page 751]]
[GRAPHIC]
[TIFF OMITTED]
TR05JA06.016

L. Summary of Major Comments

EPA received significant public comment on the analysis of benefits
and costs of the August 11, 2003 proposed LT2ESWTR in the following
areas: Cryptosporidium occurrence, drinking water consumption,
Cryptosporidium infectivity (i.e., dose-response), and valuation of
benefits. The following discussion summarizes public comment in these
areas and EPA's responses.
1. Cryptosporidium Occurrence
With respect to the analysis of Cryptosporidium occurrence, two
areas that received significant public comment are the quality of the
ICR and ICRSS data sets (i.e., whether the estimates derived from them
should be regarded as equally plausible) and the treatment of samples
in which no Cryptosporidium is detected (i.e., observed zeros).
a. Quality of the ICR and ICRSS data sets. As noted earlier, the
ICR, ICRSSM, and ICRSSL data sets differ significantly in the high
concentration portion of the occurrence distribution (e.g., 90th
percentile). While the measurement method employed in the ICRSS had
higher recovery and less variable volumes assayed, the ICR produced a
much greater number of assays and source waters sampled. Lacking a
technical basis to conclude that one data set provides a better
estimate, EPA conducted separate analyses of costs and benefits for all
three data sets. EPA requested comment on this approach.
The majority of commenters on this issue supported EPA's approach
of analyzing the three data sets separately to represent uncertainty
about occurrence. Two commenters suggested that the ICR data would be
more reliable for estimating national occurrence due to the larger
number of samples, while two others viewed the ICRSS data as more
reliable due to the improved analytical method. No commenters provided
a technical analysis indicating that one data set is more accurate.
Given these comments, EPA has retained the approach of analyzing costs
and benefits separately for each occurrence data set in today's final rule.
b. Treatment of observed zeros. One commenter remarked that the
majority of samples in which no oocysts were detected (i.e., observed
zeros) likely contained no oocysts in the volume assayed. This
commenter was concerned with a parameter in EPA's occurrence analysis
model for ``true zero,'' which characterizes the likelihood that a
source water is entirely free of Cryptosporidium at all times. In EPA's
model, the true zero parameter was assigned a value of 0.1 percent. As
described in USEPA (2005b), EPA based this assumption on the finding
that intensive sampling of surface waters usually detects
Cryptosporidium, even in protected watersheds. The commenter concluded,
however, that the true zero parameter resulted in the model assigning a
value of at least 1 oocyst to 99.9 percent of samples.
EPA responds that the true zero parameter in the occurrence
analysis model does not operate in this way. While the model is set-up
to estimate mean source water concentrations and not the concentrations
in individual volumes assayed, the model recognizes that the majority
of samples in the ICR and ICRSS contained no oocysts. The model does
assume that few, if any, of the source waters sampled in these surveys
never contained a single oocyst (the meaning of the true zero
parameter). EPA has clarified the definition of the true zero parameter
in USEPA (2005b). EPA has also conducted a sensitivity analysis in
which the true zero parameter was varied from values of 0 to 50
percent, with little effect on estimates of risk, benefit, and cost for
today's rule.
2. Drinking Water Consumption
Two commenters were concerned with the distribution for drinking
water consumption that EPA used in the proposed LT2ESWTR. This
distribution, which was based on a 1994-1996 survey by the United
States Department of Agriculture (USDA), reflects water consumption
from all sources. Commenters recommended two modifications to this
approach: (1) Adjust the distribution to account for factors like
bottled water and boiled water use; and (2) use an alternative
distribution from the USDA survey that reflects consumption of
community water system (CWS) water only.

[[Page 752]]

In response, EPA agrees that the distribution should be adjusted to
remove consumption attributable to bottled water. For the consumption
distribution in today's final rule, EPA subtracted bottled water usage,
based on information in the USDA survey, which had the effect of
reducing consumption by approximately 14 percent in comparison to the
proposal. EPA does not have information on the effectiveness of heating
water to make coffee or tea for inactivating Cryptosporidium and has
not modified the consumption distribution on this basis.
EPA continues to believe that the USDA distribution for consumption
of water from all sources, minus bottled water consumption, provides
the best available estimate for consumption of water from CWSs for
people served by CWSs. The USDA distribution for consumption of CWS
water only, which a commenter recommended, includes people not served
by CWSs (e.g., people with private wells). Inclusion these individuals
has the effect of underestimating the consumption of CWS water for
people served by CWSs in this distribution. In contrast, the
distribution for consumption of water from all sources includes people
not served by CWSs and the sources those people use (e.g., private
wells). This avoids the problem of underestimating consumption for
individuals served by CWS. Accordingly, EPA has retained the use of
this distribution in today's final rule, with the adjustment stated
previously for bottled water consumption.
3. Cryptosporidium Infectivity
In regard to Cryptosporidium infectivity (i.e., dose-response
assessment), EPA received significant comment on limitations in the
human feeding studies (e.g. representativeness of Cryptosporidium
isolates used in the studies, numbers of subjects) and uncertainty in
extrapolating from high study doses to low drinking water doses. EPA
believes that the statistical analysis of dose-response data, as
described in USEPA (2005a), properly accounted for these limitations
and uncertainties.
The statistical models used by EPA treated the isolates studied as
a random sample from a larger population of environmental isolates,
treated the subjects studied as a random sample from the larger
population of healthy individuals, and treated each individual's
outcome as a chance event, where the infection probability is a
function of the challenge dose. Collectively, these uncertainties
contributed to the significant uncertainty in EPA's estimate of the
likelihood of infection given one oocyst ingested.
Since the LT2ESWTR proposal, EPA has reviewed results from
additional human feeding studies with Cryptosporidium isolates and
analyzed data from these and the feeding studies considered for the
proposal with additional dose-response models (USEPA 2005a). As
described in Chapter 5 and Appendix N of the LT2ESWTR EA, the
infectivity estimates from the proposal are near the middle of the
range of estimates derived with the additional feeding study data and
dose-response models. Further, the mean estimates from these new
analyses fall within the 90th percentile uncertainty bounds for
infectivity estimates from the proposal (USEPA 2005a). Consequently,
EPA believes that the infectivity estimates from the additional feeding
study data and dose-response models are consistent with and supportive
of the estimates of infectivity from the proposal. Further, EPA's
estimates of infectivity are consistent with data on the infectivity of
Cryptosporidium in the 1993 Milwaukee outbreak (USEPA 2005a).
4. Valuation of Benefits
In the area of benefits valuation, EPA received significant public
comment on the valuation of morbidity, valuation of lost time under the
Enhanced COI approach, and unquantified benefits.
a. Valuation of morbidity. EPA received a comment that endemic
cases that do not show up in public health surveillance data may be too
mild (and perhaps even asymptomatic) to be economically significant.
EPA believes endemic cases are significant in terms of public health
risk and economic impacts. As discussed earlier, only a small fraction
of the millions of cases of gastrointestinal illnesses are traced to a
specific illness (such as cryptosporidiosis); yet endemic disease
clearly exists and those illnesses, even if mild, have public health
consequences and economic impacts (e.g., missed work). For example, the
benefits model in the EA assumes that 88 percent of all cases are mild,
and yet those illnesses represent significant impacts nationally.
Further, the risk assessment model separately computes infections and
illnesses. Thus, asymptomatic infections are excluded; only avoided
illnesses are assigned monetary benefits.
b. Valuation of lost time under the enhanced cost of illness (COI)
approach. One commenter extensively questioned the approach used to
value lost leisure and nonwork time under the Enhanced COI approach,
noting concerns about the relationship of the approach to standard
economics practices, the plausibility of the resulting values, and the
extent of peer review. The following discussion summarizes EPA's
responses on these issues.
As discussed in detail in the EA (USEPA 2005a), EPA recognizes that
the preferred approach for valuing health risk reductions is to rely on
estimates of individual willingness to pay (WTP). In the absence of
suitable WTP estimates, analysts often rely on approaches similar to
the Traditional COI approach used for this rule, as noted by the
commenter. However, empirical research as well as theoretic concerns
suggest that these types of COI approaches will generally understate
true WTP.
EPA designed the Enhanced COI approach to correct for one potential
source of understatement--the impact of illness on unpaid work and
leisure time. While the Enhanced COI approach is innovative, it is
rooted in standard welfare economic theory and builds on approaches
used to value time in numerous studies in the labor, transportation,
recreation, and health economics literature. The commenter is
concerned, however, that the Enhanced COI approach values nonwork time
at a higher rate than many recreational studies, several of which value
travel time at one-third of the wage rate. EPA's extensive review of
the recreational literature suggests, however, that there is no
consensus regarding the value of travel time, as discussed in the
Appendix P of the EA (USEPA 2005a). In addition, travel has both
pleasant and unpleasant aspects and hence may be valued less than other
leisure activities, many of which may be valued at a rate higher than
foregone wages.
To test the plausibility of the results, the commenter compares the
value of a ``lifetime case'' of cryptosporidiosis to the value of
statistical life (VSL) and suggests that the results (which show that
such a case would be roughly 70 percent of VSL) are improbably high.
However, EPA believes that this comparison is seriously flawed. There
is no generally accepted standard for determining whether values for
nonfatal risk reductions are ``reasonable'' compared to values for
fatal risk reductions. In addition, the calculation of the value of a
lifetime case of cryptosporidiosis contains several computational
errors, and represents the loss of all waking time (not just losses
attributable to cryptosporidiosis) and so is seriously overstated.
Perhaps most important, the approach used to value

[[Continued on page 753]]

Notices For
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994

National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule

Local Navigation