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Clean Water Act Section 403
A Framework For Ecological Risk
Assessment
Background
In 1972, Congress passed the Federal Water Pollution
Control Act, commonly known as the Clean Water Act
(CWA). Under the CWA, point source discharges (i.e.,
discharges from municipal and industrial facilities) to
waters of the United States must obtain a National
Pollutant Discharge Elimination System (NPDES)
permit, which requires compliance with technology- and
water quality-based treatment standards. In addition,
because of the complexity and ecological significance of
marine ecosystems, discharges to the territorial seas and
beyond must also comply with section 403 of the CWA,
which specifically addresses impacts from such point
sources on marine resources. The section 403 program
was one of the first of EPA's programs to incorporate
ecological risk assessment as part of the evaluation of the
impacts of point source discharges on the marine
environment.
Section 403 Requirements
Section 403 of the CWA provides that point source
discharges to the territorial seas, contiguous zone, and
oceans are subject to regulatory requirements in addition to the technology- or water quality-based requirements applicable to typical discharges. The section 403
requirements are intended to ensure that no unreasonable degradation of the marine environment will occur
as a result of the discharge and to ensure that sensitive
ecological conununities are protected. These requirements can include ambient monitoring programs
designed to determine degradation of marine waters,
alternative assessments designed to further evaluate the
consequences of various disposal options, and pollution
prevention techniques designed to further reduce the
quantities of pollutants requiring disposal and thereby
reduce the potential for harm to the marine environment. If section 403 requirements for protection of the
ecological health of marine waters are not met, an
NPDES permit will not be issued.
In assessing the potential effects of a marine discharge
during permit application review, the permitting
authority evaluates the impact of a marine discharge on
the biological community based on ecological, social,
and economic factors. Under the provisions of section
403, the permitting authority can require the permit
applicant to provide the information necessary to
conduct such an evaluation.
Ocean Discharge Guidelines
To implement section 403, EPA developed the Ocean
Discharge Guidelines (40 CFR Part 125, Subpart M
[45 FR 65942, October 3, 1980]), which specify the
ecological, social, and economic factors to be used by
permit writers when they evaluate the impact of a
discharge on the marine environment. The 10 ocean
discharge guidelines to be considered in determining
whether unreasonable degradation of the marine
environment will occur are as follows:
- (1)Quantities, composition, and potential bioaccumulation or persistence of the pollutants to be discharged.
- (2)Potential transport of the pollutants by biological, physical or chemical processes.
- (3)Composition and vulnerability of potentially exposed biological communities, including
- unique species or communities,
- endangered or threatened species, and
- species critical to the structure or function of the ecosystem.
- (4)Importance of the receiving water area to the surrounding biological community, e.g.,
- spawning sites,
- nursery/forage areas,
- migratory pathways, and
- areas necessary for critical life stages / functions of an organism.
- (5)The existence of special aquatic sites, including (but not limited to)
- marine sanctuaries/refuges,
- parks,
- monuments,
- national seashores,
- wilderness areas, and
- coral reefs/seagrass beds.
- (6)Potential direct or indirect impacts on human health.
- (7)Existing or potential recreational and commercial fishing.
- (8)Any applicable requirements of an approved Coastal Zone Management Plan (CZMP).
- (9)Such other factors relating to the effects of the discharge as may be appropriate.
- (10)Marine water quality criteria.
Much of the information necessary to make these
evaluations is usually already available to the permitting
authority from previous scientific studies, permit
evaluations, or other data collection activities. Additional information may be requested from the applicant
when necessary to help the permit writer make decisions
regarding the permit.
In those cases where there is insufficient information to
support a finding of "no unreasonable degradation,"
applicants must demonstrate that the discharge will not
cause "irreparable harm." When the permitting authority makes a determination of no irreparable harm, a
permit may be issued while confirmatory data on
ecosystem health are gathered to be evaluated prior to
reissuance of the permit. These data are collected as
part of a monitoring program to assess the impact of the
discharge on water, sediment and biological quality, as
well as an assessment of alternative sites for the discharge or disposal of the wastewater. Data are also
gathered through monitoring compliance with all other
conditions in the permit.
EPA has identified more than 300 facilities subject to
section 403 requirements under individual permits.
Approximately 2,500 oil and gas exploration and
production platforms must also meet section 403
requirements. These facilities are covered in five
general permits in Alaska and the Gulf of Mexico. One
general permit issued in Alaska covers approximately
300 seafood processing facilities, including both land-based facilities and seagoing vessels.
403 Authority
Statutory Authority: Section 403 of the Clean Water Act (33 U.S.C. Section 1343).
Regulatory Authority: Ocean Discharge Criteria Title 40, Part 125, Subpart M. Code of Federal Regulations (40 CFR 125.120-125.124).
Regulated Community: Point sources (i.e., industrial and municipal facilities) discharging seaward of the baseline of the territorial sea.
Key Section 403 Definitions
Unreasonable Degradation
- Significant adverse changes in ecosystem diversity, productivity, and stability of the biological community within the area of discharge and surrounding biological communities;
- Threat to human health through direct exposure to pollution or through consumption of exposed aquatic organisms; or
- Unreasonable loss of aesthetic, recreational, scientific, or economic value in relation to the benefit derived from the discharge.
Irreparable Harm
- Significant undesirable effects that are irreversible after cessation or modification of the discharge.
Baseline
- Defines the innermost boundary of the territorial seas; generally, the mean low water mark.
Ecological Risk Assessment and the 403 Process
As described by EPA in its Framework for Ecological
Risk Assessment (1992), ecological risk assessment is
the evaluation of the likelihood that adverse ecological
effects might occur as a result of exposure to one or
more environmental stressors. An environmental
stressor is any physical, chemical, or biological factor
that can cause an adverse environmental effect.
Common environmental stressors include pollutants
such as pesticides and organic chemicals, loss or alteration of habitat, and sudden or extreme changes
in temperature, Ecological effects commonly evaluated include mortality and reproductive or developmental abnormalities in fish, marine mammals, and
other marine organisms; the types and magnitude of
those effects; and the likelihood of recovery. Ecological risk assessment also involves evaluating ecological sustainability. Ecological sustainability entails
balancing ecological risks with socioeconomic factors
to determine an acceptable level of health and quality
of an ecological system.
Under the National Pollutant Discharge Elimination
System (NPDES) program, dischargers must achieve
compliance with national minimum technology-based
treatment requirements and any additional requirements necessary to meet state water quality standards.
This approach helps to ensure that the designated
uses of the receiving waters (e.g., fishable, swimmable) are not impaired. Section 403 can be used to
require an evaluation of ocean discharges that looks
beyond potential for water quality degradation.
Specifically, section 403 provides for evaluation of the
ecological risks and impacts associated with the
discharge. The 10 guidelines listed earlier incorporate not only water quality impacts, but also impacts
on the biological community and human health.
To assess potential impacts posed by a discharge, site-specific determinations of the magnitude of potential
ecological risks are made. For example, a discharge
might not cause long-term water quality degradation,
but it might contain levels of contaminants that are
harmful to marine organisms or entire marine
communities in the vicinity of the discharge, especially benthic (bottom) communities, such as coral
habitat, seagrass meadows, or shellfish beds. These
communities are important individually and also
make up part of the entire ecosystem, which directly
or indirectly affects human health, (e.g., fish consumption, human contact, etc.). By measuring and
evaluating ecological health -- in this case, marine
plant and animal life -- we can better understand the
risks and impacts pollutants pose to human health
and welfare and make informed permitting decisions.
Our natural resources are not unlimited. The use of
natural resources carries with it an obligation to
protect those resources for the future. The purpose of
ecological risk assessment is to gain an improved
understanding of the magnitude and likelihood of
adverse environmental responses to human activities
so we can make informed decisions based on the best
scientific data and knowledge. Ecological risk
assessment however, does not preclude human
activity in the environment. Rather, when appropriately carried out, it should be used to identify
situations where ecological sustainability is threatened.
EPA is committed to improving its decision-making
capabilities by using ecological risk assessment technologies, such as section 403 Ocean Discharge Criteria
Evaluations to protect both human and ecological health
to the greatest extent possible.
Contact Information
U.S. Environmental Protection Agency
Office of Wetlands, Oceans and Watersheds
Oceans and Coastal Protection Division
1200 Pennsylvania Avenue, NW (4504T)
Washington, DC 20460
(202) 566-1200
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