Watershed-Based
Needs Accounting
The reporting of needs in prior CWNSs has focused
on individual facilities, aggregated by State. As water quality
management becomes more sophisticated, there will be a greater
emphasis on the watershed as a water quality planning unit to
attain water quality goals. This emphasis is expected to provide
a more comprehensive and efficient basis for water quality planning.
This section presents three examples to demonstrate how multiple
pollution sources can be addressed together. The next CWNS will
explore the watershed approach in greater detail.
The term watershed refers to a geographic area in which
water, sediments, and dissolved materials drain to a common outlet:
a point on a larger stream, a lake, an underlying aquifer, an
estuary, or an ocean. This area is also called the drainage
basin of the receiving waterbody. A watershed-based management
approach allows an agency to consider not only the water resource
itself, but also the land from which the water drains and activities
that are undertaken on that land. This type of holistic planning
helps agencies target the principal water quality problems regardless
of their source.
The watershed approach makes sense for financial, environmental,
and community-building reasons. It facilitates program integration,
promotes public participation, and focuses energy on environmental
results. Coordinating efforts across traditional program areas
(for example, drinking water protection, pollution control, fish
and wildlife habitat protection, water supply, transportation,
and power generation) allows for planners to look at all the
issues within watersheds. This results in a better understanding
of the cumulative impact of various human activities.There are
several reasons to report needs on a watershed
basis. Many States are moving toward basing their water quality
work on watersheds. This allows the State to assess both the point
and nonpoint pollution sources in the watershed, and to address
them in the most cost-effective way. With limited resources at
all levels of government, watershed-based planning and assessment
allow States to focus on their highest priorities in a holistic
manner.
The following case studies show the benefits of accounting for
needs on a watershed basis. Watershed-based needs accounting links
the land use in the watershed, all the potential sources of pollution
in the watershed, and the eligible needs to the waterbody. The
State then has an idea of the effort required to meet water quality
standards for that particular waterbody.
Wisconsin: Yahara-Monona Watershed
The Yahara-Monona watershed, depicted in Figure 11, is a 60,160-acre
(94 square mile) drainage area located entirely within Dane County,
Wisconsin. More than 60 percent of the land use in the watershed
is classified as urban or urbanizing. The remaining land use is
considered rural, with agricultural lands being prevalent in the
southern part of the watershed. The watershed includes parts of
three cities (Madison, Monona, and Fitchburg), one village, and
four towns. The City of Madison accounts for approximately half
of the total land area in the watershed. The average annual precipitation
is approximately 31 inches.
Water quality problems in the watershed include low gradients and
low flows, channel straightening, sedimentation, and excessive
aquatic plants. The three largest lakes in the watershed are all
classified as eutrophic (nutrient rich). Previously, the water
quality of the lakes has been affected by municipal and industrial
sewage discharges, which have now been diverted around the lakes.
The levels of phosphorus, sediments, and metals all need to be
reduced.
Models were used to estimate the amount of various pollutants that
might be discharged from urban and agricultural lands. The pollutant
load estimates were used to develop  pollution
reduction targets in the watershed to meet water quality goals.
The needs identified for the Yahara-Monona watershed are listed
in Table 7. The needs for wastewater treatment (Categories I and
II) are for the Nine Springs wastewater treatment facility, which
treats the waste from the Madison Metropolitan Sewer District.
The SW needs include those referenced in the City of Madison's
Phase I SW permit. Finally, the needs that are required to control
rural NPS pollution, primarily agricultural, are presented. Calculating
these needs on a watershed basis allows the State to evaluate
the cost of different controls, and their expected effect on water
quality, to determine the best approach to solving their water
quality problems. 
Vermont: LaPlatte River Watershed
The LaPlatte River drains a 33,100-acre (51.7 square mile) watershed
in southwestern Chittenden County, Vermont. The watershed is depicted
in Figure 12. Approximately 45 percent of the land use is agricultural,
34 percent is forested, and less than 10 percent is residential.
The remaining land uses are open, wetland, water, or transportation.
The total population residing in towns in the watershed is fewer
than 6,000. The average annual precipitation is 33.5 inches.
The primary water quality impair-ment in the LaPlatte River, and
in Lake Champlain into which it drains, is excessive phosphorus.
Phosphorus levels are sufficiently high to cause severe eutrophication
and impairments to recreational use. Currently, two municipal
wastewater treatment facilities and one industrial facility discharge
into the watershed. Runoff from agricultural and urban areas also
contributes to excessive phosphorus loadings. 
A phosphorus loading study of Lake Champlain from the 31 major
tributaries flowing into the lake was conducted. Phosphorus load
reductions were assigned to each lake segment subwatershed to
achieve the established in-lake water quality standards for phosphorus.
A model was developed to estimate the total phosphorus load from
crop/pastureland, animal facilities, and urban areas. Four strategies
were developed to
achieve a 20 percent phosphorus reduction. The estimated needs
for these four strategies were then computed.
The public was involved through a local steering committee that
provided input and served as a "reality check" for output and
other results. Meetings were conducted to inform the public regarding
project goals and objectives, progress, and findings. 
As shown in Table 8, Scenario 1 allocated the entire load reduction
to agriculture at an estimated cost of $1.95 million. Scenario 2
modeled the cost as if an equal percentage of the phosphorus reduction
were taken from both agriculture and urban areas. Scenario 3 modeled
the cost if half of the phosphorus reduction was from agriculture
and half was from urban areas. Finally, Scenario 4 modeled the
cost if both agriculture and urban areas contributed an equal
dollar amount for the phosphorus reduction.
Scenario 1, in which the entire reduction is taken from the agricultural
land, is the least costly scenario. This is because of the lower
cost of some agricultural controls compared to urban controls.
In this case, assessing needs on a watershed basis allows for
a comparison of various pollution sources affecting a waterbody.
This provides a holistic approach to control those sources.
Tennessee: Richland Creek Watershed
The Richland Creek Watershed, depicted in Figure 13, is a 311,125-acre
(486 square mile) drainage area located in Giles, Lawrence, Marshall,
and Maury Counties. The watershed is inhabited by approximately
10,000 people, of whom 90 percent depend on its water for domestic
use. Approximately 60 percent of the land cover is agricultural
row crops and pasture. The remaining land cover comprises forest
(38 percent) and urban (2 percent).
 The
largest urban area is Pulaski, which encompasses 1.2 percent of
the watershed. Annual precipitation is 55 inches, with the heaviest
rainfall in the winter and spring.
Water quality problems are primarily from NPS pollution. Runoff
from agricultural plots contributes to increased sedimentation
and nutrient enrichment. Runoff from a private solid waste facility
has also been problematic. Additionally, the City of Pulaski has
identified storm water runoff from asphalt areas as a source of
water quality problems.
Concern by local officials and private citizens has resulted in
an awareness of water quality problems. The City of Pulaski has
undertaken a project to reduce the influence of urban runoff by
constructing buffer strips in problem areas. Several local, State,
and Federal agencies, as well as Tennessee Technological University,
have cooperatively developed a model to identify problem areas,
explore corrective actions, and provide a cost-benefit analytical
procedure. This process was developed using existing surface and
ground water models, integrated with geographic information system
technology, to provide local citizens with a tool for watershed
planning.
The needs identified for a subwatershed of the Richland Creek Watershed
are listed in Table 9. These scenarios were based on local citizen
visions for the condition of the subwatershed and the cost effectiveness
of remedial actions. The output is based on a Watershed Quality
Index (WQI) derived from the developed model (a higher WQI score
indicates better water quality). A single storm event of 1 inch
was used in all scenarios. The results show that a relatively
low-cost option, such as adding buffer strips around waterbodies,
would have about the same impact on the watershed as upgrading
the treatment plant to tertiary treatment. These changes were
also compared to a scenario in which all land in the watershed
would be reforested, which would achieve the best possible water
quality. 
What Can Be Concluded from These Case Studies?
Assessing needs on a watershed basis encourages integrated planning,
encompassing all the sources within a watershed. As these examples
show, various scenarios can be evaluated, with the cost and water
quality improvement to the watershed estimated. This allows States
to address their water quality concerns in the most cost-effective
manner and can help form the basis for such management approaches
as waste load allocations and effluent trading. Future CWNSs will
provide an opportunity to integrate multiple needs on a watershed
basis. The goal will be to identify the level of needs required
to achieve water quality compliance for individual watersheds.
301(h) Ocean Discharge Waiver
A variance (authorized under Section 301(h) of the CWA) from secondary
treatment requirement for treatment facilities discharging to
bays or estuaries.
Advanced Treatment
See Categories of Needs: Category II.
Animal Unit (AU)
A unit of measurement for any animal feeding operation. 1,000 animal
units is equal to 1,000 slaughter and feeder cattle or 714 dairy
cattle or 2,500 swine weighing over 25 kilograms (approximately
55 pounds) or 10,000 sheep or 500 horses.
Atmospheric Deposition
A process by which airborne particles (sometimes pollutants) are
deposited on the ground. After their deposition, these particles
may be transferred to surface waters by storm water runoff.
Best Management Practice (BMP)
A practice or combination of practices that are determined to be
an effective and practicable (including technological, economic,
and institutional considerations) means of controlling point and
nonpoint pollutants at levels compatible with environmental quality
goals.
Best Management System (BMS)
A combination of conservation practices or management measures
that, when applied, will achieve desired nonpoint source pollution
control through reduced transport of sediment, nutrients, and
chemicals into surface and ground water.
Biochemical Oxygen Demand (BOD/BOD5)
Amount of oxygen consumed by aerobic bacteria to decompose organic
matter. Used to measure extent of pollution by sewage or industrial
waste. BOD5 refers to the 5-day test to determine BOD.
Categories of Needs
Needs estimates address the following categories:
1. Secondary Treatment (Category I)
The minimum level of treatment that must be maintained by all treatment
facilities except those facilities granted ocean discharge waivers
under section 301(h) of the CWA. Treatment levels are specific
in terms of the concentration of conventional pollutants in the
wastewater effluent discharged from a facility after treatment.
Secondary treatment typically requires a treatment level that
will produce an effluent quality of 30 mg/l of both BOD5
and total suspended solids (TSS), although secondary treatment
levels required for some lagoon systems may be less stringent
than this. In addition, the secondary treatment must remove 85
percent of BOD5 and TSS from the influent wastewater.
Needs to attain incremental reductions in conventional pollutant
concentrations beyond secondary treatment requirements are included
in Category II.
2. Advanced Treatment (Category II)
A level of treatment more stringent than secondary treatment or
a significant reduction in nonconventional pollutants present
in the wastewater treated by a facility. Needs reported in this
category are necessary to attain incremental reductions in pollutant
concentrations beyond basic secondary treatment.
3. Infiltration/Inflow (I/I) Correction (Category
IIIA)
Control of the problem of penetration into a sewer system
of water other than wastewater from the ground through such means
as defective pipes or manholes (infiltration) or from sources
such as drains, storm sewers, and other improper entries into
the system (inflow). Included in this category are costs for correction
of sewer system infiltration/inflow problems. Costs also are reported
for preliminary sewer system analysis and for detailed sewer system
evaluation surveys.
4. Replacement/Rehabilitation of Sewers (Category
IIIB)
Reinforcement or reconstruction of structurally deteriorating sewers.
This category includes cost estimates for rehabilitation of existing
sewer systems beyond those for normal maintenance. Costs are reported
if the corrective actions are necessary to maintain the structural
integrity of the system.
5. Collector Sewers (Category IVA)
Pipes used to collect and carry wastewater from a sanitary or industrial
wastewater source to an interceptor sewer that will convey the
wastewater to a treatment facility. The needs in this category
include the costs of constructing new collector sewer systems
and appurtenances.
6. Interceptor Sewers (Category IVB)
Major sewer lines receiving wastewater flows from collector sewers.
The interceptor sewer carries wastewater directly to the treatment
facility or to another interceptor. The needs in this category
include costs for constructing new interceptor sewers and pumping
stations necessary for conveying wastewater from collection sewer
systems to a treatment facility or to another interceptor sewer.
7. Combined Sewer Overflow (CSO) Controls (Category
V)
Facilities or measures to achieve water quality objectives by preventing
or controlling periodic discharges of a mixture of storm water
and untreated wastewater (combined sewer overflows) that occur
when the capacity of a sewer system is exceeded during a rainstorm.
This category does not include costs for overflow control allocatable
to flood control or drainage improvement, or for treatment or
control of storm water in separate storm and drainage systems.
8. Storm Water (SW) (Category VI)
Activities to plan and implement municipal storm water management
programs pursuant to NPDES permits for discharges from MS4s. These
include structural and nonstructural measures that (1) reduce
pollutants from runoff from commercial and residential areas that
are served by the storm sewer, (2) detect and remove illicit discharges
and improper disposal into storm sewers, (3) monitor pollutants
in runoff from industrial facilities that flow into municipal
separate storm sewer systems, and (4) reduce pollutants in construction
site runoff.
9. Nonpoint Source (NPS) Pollution Controls (Category
VII)
Activities to plan and implement programs to control NPS pollution
of both surface water and ground water. These include structural
and nonstructural measures to reduce or eliminate pollutants from
both urban (non-Phase I SW) and rural areas. This category is
further divided into: (A) agricultural cropland sources; (B) agricultural
animal sources; (C) silviculture sources; (D) urban sources (excluding
those covered in Category VI); (E) ground water protection; (F)
estuary protection; and (G) wetland protection.
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