Clean Water Act and Pollutant Total
Maximum Daily Loads (TMDLs)
Claudia Copeland
Specialist in Resources and Environmental Policy
September 21, 2012
Congressional Research Service
7-5700
www.crs.gov
R42752
CRS Report for Congress
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epared for Members and Committees of Congress
Clean Water Act and Pollutant Total Maximum Daily Loads (TMDLs)
Summary
Section 303(d) of the Clean Water Act (CWA) requires states to identify waters that are impaired
by pollution, even after application of pollution controls. For those waters, states must establish a
total maximum daily load (TMDL) of pollutants to ensure that water quality standards can be
attained. A TMDL is both a quantitative assessment of pollution sources and pollutant reductions
needed to restore and protect U.S. waters and a planning process for attaining water quality
standards. Implementation of section 303(d) was dormant until states and the Environmental
Protection Agency (EPA) were prodded by lawsuits. The program has been controversial, in part
because of requirements and costs faced by states to implement this 40-year-old provision of the
law, as well as industries, cities, farmers, and others who may be required to use new pollution
controls to meet TMDL requirements.
Despite controversies, the TMDL program has become a core element of overall efforts to protect
and restore water quality. States and EPA develop several thousand TMDLs annually, but many
more need to be completed. The most recent information indicates that over 41,000 waterbodies
do not meet water quality standards and need a TMDL to initiate corrective measures. The 303(d)
program has evolved, and especially during the last decade, EPA and states have addressed more
complex issues, including TMDLs involving both point (direct discharges) and nonpoint sources
(diffuse discharges) such as stormwater; TMDLs for less-traditional causes of impairment such as
ocean acidification and climate change; TMDLs for pollutants such as mercury that involve
coordination among water, air, and other environmental programs; and multi-jurisdictional
TMDLs.
The largest multi-jurisdictional TMDL, for the Chesapeake Bay watershed, has drawn
considerable attention. It was developed by EPA and was necessitated because previous largely
voluntary restoration efforts by the Bay jurisdictions were insufficient to attain water quality
standards. It addresses all segments of the Bay and its tidal tributaries that are impaired from
discharges of nitrogen, phosphorus, and sediment, with a goal of having TMDL implementation
measures in place by 2025. The Chesapeake Bay TMDL has a number of novel elements,
including Watershed Implementation Plans in which the jurisdictions identify specific measures
to achieve needed pollutant reductions, and biennial reports to the public on progress in
implementation. The Bay TMDL has been controversial with a number of groups concerned
about the costs of implementation and the likely mandatory nature of many of EPA’s and states’
actions. EPA’s authority to develop the TMDL has been challenged in a lawsuit.
When a TMDL is developed, implementation is a major uncertainty. First, section 303(d) does not
require implementation, and states’ strategies for implementation vary widely. Only a few have
laws requiring implementation plans, while many others rely on less structured policies. Second,
a number of barriers to implementation can be identified. The most prominent is insufficient
funding, but technical impediments such as insufficient scientific data also are a challenge. At the
same time, factors that may aid effective implementation can be identified, including active
involvement of stakeholders and governments, and adequate resources.
The TMDL program is in a period of transition and increasingly is addressing new challenges—
more complex TMDLs, larger scale impairments, and nonpoint sources. Other than recent
oversight hearings on the Chesapeake Bay TMDL, Congress has not shown active interest in the
TMDL program for more than a decade. Some stakeholders, especially states, believe that several
issues present Congress with an opportunity to examine the TMDL provisions of the CWA.
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Clean Water Act and Pollutant Total Maximum Daily Loads (TMDLs)
Contents
Background...................................................................................................................................... 1
Implementation of Section 303(d) ................................................................................................... 2
Revising the TMDL Rules......................................................................................................... 3
Recent Developments and Challenges ...................................................................................... 5
Administrative Developments............................................................................................. 5
Addressing Nonpoint Sources in TMDLs ........................................................................... 5
Stormwater .......................................................................................................................... 6
Mercury............................................................................................................................... 7
Ocean Acidification............................................................................................................. 8
Climate Change................................................................................................................... 9
Multi-Jurisdiction TMDLs ................................................................................................ 10
Chesapeake Bay TMDL .......................................................................................................... 11
Outside Assessments of the TMDL Program .......................................................................... 15
Factors Affecting Implementation ........................................................................................... 16
Conclusion ..................................................................................................................................... 18
Contacts
Author Contact Information........................................................................................................... 19
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Clean Water Act and Pollutant Total Maximum Daily Loads (TMDLs)
Background
The Clean Water Act (CWA) contains a number of complex and interrelated elements of overall
water quality management. Foremost is the requirement in section 303 that states establish
ambient water quality standards for water bodies, consisting of the designated use or uses of a
water body (e.g., recreational, public water supply, or industrial water supply) and the water
quality criteria which are necessary to protect the use or uses. Standards are then used to
determine which waters must be cleaned up, how much effluent may be discharged, and what is
needed for protection. Through permitting, states or the Environmental Protection Agency (EPA)
impose wastewater discharge limits on individual industrial and municipal facilities to ensure that
water quality standards are attained. However, Congress recognized in the act that, in many cases,
pollution controls implemented by industry and cities would be insufficient to attain and maintain
water quality standards, due to pollutant contributions from other unregulated sources.
Under CWA section 303(d), states must identify waters for which discharge limits specified in
permits are not stringent enough to achieve established water quality standards, after
implementation of technology-based controls by industrial and municipal dischargers. For each
waterbody or segment, states1 are required to set a total maximum daily load (TMDL) of
pollutants at a level that ensures that applicable water quality standards can be attained and
maintained. A TMDL is essentially a pollution budget, a quantitative estimate of what it takes to
achieve state water quality goals, setting the maximum amount of pollution a waterbody can
receive without violating water quality standards, including a margin of safety to account for
seasonal variations and uncertainty between pollutant loads and the quality of receiving waters.
As such, TMDLs provide a scientific calculation of how much pollutant loads need to be reduced
to meet those standards.
A TMDL is both a planning process for attaining water quality standards and a quantitative
assessment of problems, pollution sources, and pollutant reductions needed to restore and protect
a river, stream, or lake. TMDLs may address all pollution sources and allocate needed pollutant
reductions among categories of sources that contribute to the water quality impairment, including
point sources, such as municipal sewage treatment or industrial plant discharges (wasteload
allocation or WLA); and nonpoint sources (load allocation or LA), such as runoff from roads,
farm fields, and forests, atmospheric deposition, naturally occurring sources, and background
sources of the pollutant.
The goal of the TMDL is to eliminate an impairment, not meet a pollutant limit for its own sake.
The TMDL itself does not establish new regulatory controls on sources of pollution, and it does
not set discharge limits. Nor is it self-implementing. However, when TMDLs are established,
municipal and industrial wastewater treatment plants may be required to install new or improved
pollution control technology. For waters impaired by point source discharges, TMDLs are
enforced through revisions to existing CWA permits, which include the pollutant limits and a
schedule for compliance. For waters impaired by nonpoint source runoff, because there are no
federal controls over these sources (there is no CWA permit requirement as there is for point
sources), the primary implementation tools are state-run nonpoint source management programs,
coupled with state, local, and federal land management programs and authorities, and financial
1 Reference throughout this report to states includes states, U.S. territories, and Tribes authorized by EPA to administer
water quality standards on tribal lands.
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assistance and incentive programs. States can but are not required to regulate nonpoint sources to
achieve goals set out in a TMDL. For example, farmers or ranchers may be asked by states to use
alternative methods in their operations to prevent fertilizers and pesticides from reaching streams,
and they may receive funds to help them install on-farm pollution management systems or
practices.
EPA has specific responsibilities under section 303(d). First, EPA is required to review and
approve a state’s list of impaired waters and TMDLs. Second, if a state fails to identify impaired
waters and develop a TMDL where one is needed, the CWA requires EPA to develop an impaired
waters list for the state and make its own TMDL determination. EPA is not authorized to
implement a TMDL.
Implementation of Section 303(d)
EPA acknowledges that a vigorous TMDL program is needed because significant water quality
problems persist in the nation’s waters, nearly 40 years after enactment of the CWA. An estimated
40% of the nation’s waters assessed by states do not meet water quality standards.2 TMDLs are
one element of state water quality management programs. Other activities include standard
setting, monitoring, permitting, and enforcement, and all must be integrated with the TMDL
program. Most states have lacked the resources to do TMDL analyses, which involve complex
assessment in order to ascribe and quantify environmental effects from particular discharge
sources. Baseline water quality monitoring data for the analyses (to identify impaired waters and
pollution sources) have been limited. EPA has both been reluctant to intervene in the states and
also lacked resources to do so itself. Thus, there was little initial implementation of the provision
enacted in 1972. Only in 1992 did EPA issue regulations requiring states, every two years, to list
waters that do not attain water quality standards and establish TMDLs to restore water quality.
Responding to the failure of states and EPA to meet these requirements, however, environmental
groups filed lawsuits in more than three dozen states to compel compliance with the law’s
requirements. Environmentalists see implementation of section 303(d) as important both to
achieving the overall goals and objectives of the act and to pressuring EPA and states to address
nonpoint and other sources that are responsible for many water quality impairments nationwide
but have not been well controlled. Of the suits tried or settled, nearly two dozen resulted in court
orders requiring expeditious TMDL development by states or EPA.
The TMDL litigation falls into three general categories: (1) challenges intended to compel EPA to
step in to fulfill TMDL requirements where a state has failed partially or completely to do so; (2)
challenges to EPA’s listing of impaired waters, TMDL approval decisions, or EPA’s promulgation
of TMDLs; and (3) challenges to the substance or content of TMDLs.3
Because of the lawsuits and existing requirements of the law, in 1997, EPA issued interpretive
guidance which for the first time called on states to develop long-term schedules for
implementing TMDLs. There is neither a CWA nor a regulatory deadline for states to develop
2 U.S. Environmental Protection Agency, National Water Quality Inventory: Report to Congress, 2004 Reporting
Cycle, EPA 841-R-08-001, January 2009, http://water.epa.gov/lawsregs/guidance/cwa/305b/2004report_index.cfm.
3 For information on TMDL litigation by state, see http://water.epa.gov/lawsregs/lawsguidance/cwa/tmdl/lawsuit.cfm.
However, this information is a partial list that is not comprehensive or current.
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TMDLs. Under the 1997 guidance, EPA recommends that states establish TMDLs in order to
meet water quality standards within 8 to 13 years of listing the water as impaired.4 Development
of TMDLs has increased (since 1996, states and EPA have established more than 48,000), but
many more remain to be completed. The most recent state 303(d) lists, most of them submitted in
2008 and 2010, identified over 41,000 waterbodies as not meeting water quality standards and in
need of a TMDL, affecting more than 300,000 miles of rivers and shorelines and 5 million acres
of lakes and resulting from nearly 72,000 causes of impairment.5 Nationwide, more than 50% of
all impairments are caused by nutrients and sediment, metals including mercury, and pathogens
(e.g., fecal coliform, E. coli, enterococcus bacteria, and other). Pathogens are the largest single
cause of impairments.6
Development of TMDLs does not equate automatically with restoration that attains water quality
standards. Implementation is complex and highly dependent on state and local stakeholders. It
takes time, as does demonstrating results. EPA has adopted a goal of having 3,360 waters (8.2%
of all impaired waters identified in 2002) in attainment with applicable water quality standards by
2015.7
Revising the TMDL Rules
In 1999, EPA proposed revisions to the 1992 TMDL regulations to clarify and strengthen the
program. The key proposed changes included a new requirement for a more comprehensive list of
impaired and threatened waterbodies; a new requirement that states, territories and authorized
Indian tribes establish and submit schedules for establishing TMDLs; a new requirement that the
listing methodologies be more specific, subject to public review, and submitted to EPA;
clarification that TMDLs include 10 specific elements; a new requirement for a TMDL
implementation plan (section 303(d) does not mandate implementation, a widely acknowledged
gap; see “Factors Affecting Implementation,” below); and new public participation requirements.
EPA’s proposal had few strong supporters, for varying reasons. States, which would be directly
affected by the proposal, criticized the burdens that new requirements would place on them. They
were concerned that they lack the resources to meet tight deadlines for developing and
implementing TMDLs. Further, states said that TMDLs should not necessarily be prioritized over
and should be integrated with other elements of existing water quality management programs.
Industry groups were greatly concerned about impacts of new pollution control requirements that
result from TMDLs. But, municipal and industrial point source groups urged states and EPA to
ensure that TMDL requirements do not fall disproportionately on their discharges, while possibly
failing to address nonpoint source contributions to impaired waters. Farm groups and others with
nonpoint discharges questioned EPA’s authority to include nonpoint source pollution in the
TMDL program. The forestry industry vigorously criticized potential impacts of the proposal.
Environmentalists, who support the need for a stronger and more comprehensive TMDL program,
4 This is a longer time frame than has been mandated as a result of some of the TMDL litigation. The schedules for
TMDLs in lawsuits concluded by consent decrees and settlement agreements range from 4 years to 20 years; most call
for a 10-year development schedule.
5 Many waters are impaired by more than one pollutant or other cause.
6 For information, see http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.control?p_report_type=
T#status_of_data.
7 U.S. Environmental Protection Agency, Office of Water, National Water Program Guidance, Fiscal Year 2013,
April 2012, p. 32. In 2002, states identified 39,503 specific waterbodies as impaired.
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objected to the lengthy time periods in the proposal before water quality improvements are likely
to occur. They have criticized the lack of aggressive implementation of a program that has existed
in the law since 1972.
Congressional interest was high: by the time the final rule was signed in July 2000, 13
congressional hearings had been held, and a number of legislative proposals to modify the Clean
Water Act or delay the rule had been introduced.8 EPA attempted to respond to the criticism with
flexibility on some of the most contentious points. While the revised rule was undergoing final
review, Congress adopted a provision in the FY2001 Military Constructions/FY2000 Urgent
Supplemental Appropriations Bill (P.L. 106-246), stating that no funds could be used in FY2000
or FY2001 to “make a final determination on or implement any new rule relative to” the 1999
proposal. Because President Clinton intended to sign the bill into law but opposed the TMDL
limitation, the Administration accelerated its review, allowing the EPA Administrator to sign it
before President Clinton signed the appropriations bill. In the final rule, EPA acknowledged
Congress’s action in the legislation and delayed the effective date of the rule’s changes until
October 31, 2001. The text of the final rule was published on July 13, 2000.9
The final rule built on the existing regulatory program and added details, specific requirements,
and deadlines requiring states to implement plans to clean up polluted waters. It retained key
elements of the 1999 proposal for more comprehensive identification of impaired waters,
schedules and minimum elements for TMDLs, and new public participation requirements. For
some interested parties, what was most of interest was what was not included in the final rule. In
efforts to respond to criticism, EPA dropped several provisions that were most controversial,
including some potentially affecting agriculture and forestry.10
The Bush Administration announced in October 2001 that it would delay the effective date of the
rule until May 2003, to allow for further review, but in March 2003, EPA withdrew the 2000 rule
in order to consider initiating an entirely new rule or other options. Officials said that additional
time was needed to decide whether and how to revise the program and that allowing the rule to
take effect in May 2003 would disrupt the ongoing review. No further timetable was announced.
One EPA view, widely reported at the time, was that a new rule is not essential, because states are
improving and will continue to improve the pace at which TMDLs are established, even under
existing rules. Many environmentalists have said that, short of retaining the 2000 rule, the best
action would be to leave the 1992 rules in place, because, although flawed, those rules are
preferable to a new rule that might weaken the program. Other stakeholders have urged EPA to
adopt different strategies. Many states and industries favor a rule with more flexibility than either
the 2000 rule or existing regulations. In mid-2002, EPA developed a draft revised rule which it
informally circulated among interest groups and federal agencies for many months, but it did not
propose a new rule. In early 2009, there were some reports of discussion among EPA officials of
8 During the 106th Congress, hearings were held by the House Agriculture Committee; House Transportation and
Infrastructure Committee; Senate Agriculture, Nutrition and Forestry Committee; and Senate Environment and Public
Works Committee.
9 U.S. Environmental Protection Agency, “Revisions to the Water Quality Planning and Management Regulation and
Revisions to the National Pollutant Discharge Elimination System Program in Support of Revisions to the Water
Quality Planning and Management Regulation; Final Rules,” 65 Federal Register No. 135, July 13, 2000, pp. 43586-
43670.
10 See CRS Report RL30611, EPA's Total Maximum Daily Load (TMDL) Program: Highlights of the Final Revised
Rule, by Claudia Copeland.
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reviving review of the 2000 rule, but the Obama Administration has not come forward with
proposed regulatory changes.
As a result, program requirements under the 1992 regulations and court-sanctioned TMDL
schedules remain in place and are the drivers for much of the current TMDL activity.
Recent Developments and Challenges
The earliest TMDLs developed by EPA and states often addressed impairments resulting from
single pollutants and a limited number of sources. Developing even these relatively
straightforward TMDLs presented substantial technical and scientific challenges, but the national
program has by now become a core element of overall efforts to protect and restore water quality.
States and EPA develop several thousand TMDLs annually (e.g., EPA approved 2,566 in 2010
and 2,820 in 2011). At the same time, the 303(d) program has evolved, and especially during the
last decade, EPA and states have addressed more complex issues, including TMDLs for less-
traditional causes of impairment, TMDLs involving both point and nonpoint sources, and multi-
jurisdictional TMDLs. Legal challenges continue to influence implementation of the program.
Administrative Developments
Several provisions of the CWA direct states to report periodically to EPA on water quality
conditions and trends. The 303(d) requirement to identify impaired waters is one of these
provisions. Others are found in CWA section 305(b), which calls for a biennial assessment of all
navigable waters in the state, and section 314, which requires a biennial report on water quality
conditions of lakes. Since 2001, EPA has taken steps to minimize the administrative burden on the
states of implementing these overlapping provisions by integrating the requirements into a single
submission that enables a broad-scale, national inventory of water quality conditions. These
Integrated Report (IR) requirements are detailed in guidance memoranda; the most recent was
issued in March 2011.11 The IR format uses a five-part categorization approach for classifying the
status for each water segment, ranging from Category 1 (all designated uses are supported, and no
use is threatened) to Category 5 (at least one designated use is not supported or is threatened, and
a TMDL is needed—these are the waters that comprise 303(d) lists).
EPA has issued a number of guidance and other documents to support states as they address
emerging TMDL issues and concerns, which are discussed next.
Addressing Nonpoint Sources in TMDLs
The traditional focus of the CWA has been on controlling direct pollutant discharges to surface
waters from municipal and industrial point sources, through regulations and permits. Over time,
as these sources have abated pollution, uncontrolled nonpoint sources have become a larger
relative portion of remaining water quality problems. Nonpoint source pollution results from
indirect discharges to surface waters from diffuse sources such as land runoff, precipitation,
atmospheric deposition, drainage, seepage, or hydrologic modification. Nonpoint sources (both
11 See “Information Concerning 2012 Clean Water Act Sections 303(d), 305(b), and 314 Integrated Reporting and
Listing Decisions,” http://water.epa.gov/lawsregs/lawsguidance/cwa/tmdl/ir_memo_2012.cfm.
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urban and rural) are known to cause or contribute to water quality impairments throughout the
United States.
Whether and how to address nonpoint sources has been a key issue in the TMDL program. As
previously described, when states or EPA develop a TMDL, they have flexibility in making use of
available water quality management tools to allocate pollutant reductions. They can, for example,
tighten discharge limits on point sources through enforceable permits. But municipalities and
industries contend that limiting TMDLs only to point sources imposes disproportionate
requirements on their operations, especially in waters that are impaired both by point and
nonpoint sources.
Farming and forestry groups have long been concerned about how their activities might be
addressed in TMDLs and whether they might be subject to CWA regulation of some sort, even
though the act does not provide EPA with regulatory authority over nonpoint sources. EPA only
can influence activities of nonpoint sources through use of grants and funding, such as CWA
section 319, which addresses nonpoint source pollution through state-run nonpoint pollution
management programs.12 CWA section 303(d) does not specify whether TMDLs should cover
nonpoint sources, but EPA’s long-standing interpretation has been that nonpoint sources of
polluted runoff should be addressed, along with point sources, where they contribute to water
quality impairment. That interpretation was upheld in a key court case in 2002.13
Because their pollutant contributions are intermittent and because the principal policy tools
available to government are voluntary or incentive-based programs, not regulatory programs,
addressing nonpoint pollution sources in TMDLs is more challenging than is addressing point
sources. A TMDL must include a “reasonable assurance” component that needed load reductions
can be attained, but making this demonstration can be problematic when nonpoint sources are a
significant source of impairment, since there is no permit or similar enforcement mechanism to
provide accountability. Tracking implementation of practices to manage nonpoint pollution and
verifying results are difficult, especially practices that are done voluntarily and without federal or
state cost-share assistance. Some state officials contend that TDMLs for restoring impaired waters
are ineffective when nonpoint sources with few or no controls are the main sources of
impairment.14 One observer, however, has suggested that states avoid allocating reductions to
point sources “by relying on rather fanciful reductions from nonpoint dischargers (which, because
they have no permits, can be as fanciful as one wishes).”15
Stormwater
Throughout the United States, stormwater discharges are responsible for thousands of water
quality impairments. Stormwater is generated when precipitation from rain and snowmelt events
flows over land or impervious surfaces (paved streets, parking lots, and building rooftops) and
does not percolate into the ground. It may be conveyed through pipes or ditches, or it may flow
12 While the 319 program is voluntary at the federal level, states may include regulatory components in their 319
programs.
13 Pronsolino v. Marcus, 91 F.Supp.2d 1337 (N.D.Cal 2000) aff’d, Pronsolino v. Nastri, 291 F.3d 1123 (CA9 2002).
14 Amena H. Saiyid, “TMDLs Ineffective for Waters Impaired by Nonpoint Sources, State Officials Tell GAO,” Daily
Environment Report, vol. 141 (July 24, 2012), p. A-8.
15 Oliver A. Houck, “The Clean Water Act Returns (Again): Part 1, TMDLs and the Chesapeake Bay,” Environmental
Law Reporter, vol. 41, no. 3 (2011), pp. 10208-10228, 10211.
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over land and discharge directly into a waterbody. As the runoff flows over the land or impervious
surfaces, it accumulates debris, chemicals, sediment, or other pollutants that could harm water
quality if the runoff is discharged without treatment. The most common pollutants coming from
stormwater are nutrients, pathogens, sediment, and metals, according to EPA.
Most stormwater sources are point sources, which are regulated under the federal stormwater
regulatory program and thus are subject to CWA permit requirements. This program applies to
stormwater discharges from several broad categories: municipal separate storm sewer systems
(MS4s) that serve populations greater than 100,000 and smaller MS4s in Census-defined
urbanized areas; construction activity one acre and larger; and specified categories of industrial
activity.16
Other stormwater sources are nonpoint sources and thus are nonregulated by the CWA. Sources
include runoff from residential and commercial application of fertilizer and manure, land
disturbance and erosion, and atmospheric deposition.
Many impairments result from point source and nonpoint source stormwater discharges, and
TMDLs can address both. In developing these TMDLs, data needed to characterize loads from
regulated stormwater activities are generally available from CWA permitting programs. Assigning
wasteload allocations to these sources is done by adjusting their permit requirements. Data to
characterize loads from unregulated stormwater sources can be more difficult to obtain, and
assigning cleanup obligations to them presents the types of allocation and implementation
challenges previously discussed concerning nonpoint sources generally. The TMDL also must
recognize that stormwater may not be the only source of pollutants such as nutrients or metals in
an impaired waterbody.17
Mercury
Mercury is the cause of more than 4,700 impairments in thousands of 303(d) listed waterbodies;
more than 60% of these impairments are indicated by high mercury levels in fish. Mercury
accumulates in fish tissue as methylmercury, the form that presents the greatest risk to human
health through consumption of contaminated fish.
In many waterbodies, mercury originates largely from air sources, such as coal-fired power
plants, municipal waste combustors, and medical waste incinerators that deposit mercury in
waters or on adjacent lands that then wash into nearby waters. Contributions may come from a
combination of local, regional, and international sources. In some cases, the presence of mercury
results from past practices, such as legacy gold mining, or from geologic deposits. Some mercury
may be discharged to water from existing industrial point sources, although in many waterbodies,
the amounts are very small compared to other sources, according to EPA.
Since 1996, states and EPA have developed nearly 7,000 mercury TMDLs. Given the variety of
potential mercury sources, developing and implementing TMDLs for mercury-impaired waters
16 For information, see CRS Report 97-290, Stormwater Permits: Status of EPA’s Regulatory Program, by Claudia
Copeland.
17 Pathogens, metals, nutrients, and sediments are the cause of nearly 57% of impairments in 303(d) listed waters. See
http://ofmpub.epa.gov/tmdl_waters10/attains_nation_cy.control?p_report_type=T#status_of_data. How many of those
impairments are from stormwater sources is unknown.
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often involves coordination among multiple programs—water, air, waste, and toxics programs—
and multiple stakeholders. Technical and organizational challenges can be significant, particularly
where mercury is predominantly from atmospheric sources. Water management programs
generally do not control sources of air emissions, and controlling deposition that originates
outside a single jurisdiction is difficult.
Two TMDLs that notably have addressed these types of challenges are a statewide mercury
TMDL developed in Minnesota, consisting of two regional TMDLs in the state that cover 998
waterbody/pollutant combinations, and a regional mercury TMDL developed by seven northeast
states (Connecticut, Maine, Massachusetts, New York, New Hampshire, Vermont, and Rhode
Island).18 These and many other mercury TMDLs expect to be accomplished over time through
existing and future regulatory controls outside of the CWA (such as Clean Air Act regulation of
mercury emissions from coal-fired powerplants and other sources), making it difficult to estimate
with confidence the effectiveness of mercury reduction strategies. Thus, most anticipate periodic
reevaluation by the seven participating states to determine progress and the need for additional or
revised reductions to meet water quality standards.
Ocean Acidification
Oceans naturally absorb carbon dioxide (CO2) from the atmosphere, but too much CO2 can cause
them to become overly acidic. Scientists believe that ocean acidification (OA) is primarily caused
by increasing CO2 concentrations in the atmosphere. In a 2010 report, the National Research
Council of the National Academies of Sciences concluded that ocean chemistry is changing at an
unprecedented rate and magnitude due to anthropogenic CO2 emissions and that “there is a risk of
ecosystem changes that threaten coral reefs, fisheries, protected species, and other natural
resources of value to society.”19
Activists have been pressing EPA on a variety of fronts to address the role of increasing emissions
of CO2, a greenhouse gas, on climate change, including under the TMDL program. In 2009, the
Center for Biological Diversity (CBD) sued EPA in a challenge to the agency’s approval of
Washington’s 303(d) list, because the state’s list failed to include coastal waters as impaired for
marine pH due to CO2.20 CBD also sought to force EPA to revise and strengthen its existing water
quality criterion for pH in marine waters, issued in 1976. Under the CWA, EPA issues water
quality criteria, which are scientific information regarding concentrations of specific chemicals in
water which protect aquatic life or human health. States, in turn, use these EPA-recommended
criteria as a basis for developing water quality standards. CBD argued to EPA that the existing
marine pH criterion is not protective enough to address decreasing pH levels due to increased
CO2 emissions. The group contended that if states adopted more stringent marine pH criteria in
their water quality standards, more waters likely would be identified as impaired, thus requiring
TMDLs to achieve reduction in CO2 emissions that are responsible for the standards violations.
EPA has said that it has insufficient data to revise the national marine pH criterion at this time.
18 U.S. Environmental Protection Agency, “Examples of Approved Mercury TMDLs,” http://water.epa.gov/lawsregs/
lawsguidance/cwa/tmdl/mercury.cfm.
19 National Research Council, National Academies of Science, Ocean Acidification: A National Strategy to Meet the
Challenges of a Changing Ocean, National Academies Press, 2010, p. 15. For additional information, see CRS Report
R40143, Ocean Acidification, by Eugene H. Buck and Peter Folger.
20 In chemistry, pH (potential (of) hydrogen) is a measure of the concentration of hydrogen ions in a solution, hence, its
acidity or alkalinity.
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To settle the CBD lawsuit, EPA agreed to look for opportunities to use the CWA to address OA (it
did not commit to revising the existing marine pH water quality criterion). In 2010, EPA
published a Federal Register Notice seeking public comment on what considerations it should
take into account when deciding how to address the listing of waters as threatened or impaired by
OA under the TMDL program, including how to develop TMDLs for such listed waters.21 Also as
part of the settlement, EPA subsequently issued a memorandum that advised coastal states to list
waters that do not meet standards for marine pH when data are available, but the memo did not
elevate in priority the assessment and listing of waters for OA. The memo said, “EPA recognizes
that information is absent or limited for OA parameters and impacts at this point in time and,
therefore, listing for OA may be absent or limited in many States.”22 The agency expects to
provide additional guidance to states when future OA research provides improved monitoring and
assessment methods.
Climate Change
Even for relatively straightforward impairments (e.g., a single pollutant such as a heavy metal
discharged from known sources), TMDL development is complex and resource-intensive. The
process requires extensive data on current water quality conditions, pollutants and sources
causing impairments, and modeling to analyze effects of load and wasteload allocations that will
attain water quality standards with a margin of safety. Climate change considerations add even
greater complexity to the analyses, including the need to assess future conditions that are
themselves uncertain and sources that can be both domestic and global. Nevertheless, a 2011 EPA
draft report notes that climate change may alter attainability of some designated uses and
parameters related to water quality standards (e.g., lower streamflow may increase stream
temperature) and recommends that “TMDLs and water quality standards should be examined to
ensure that these remain protective of aquatic life uses under changing climatic conditions.”23
The number of future TMDLs that could or should include potential climate change effects is
unknown. According to EPA, “It is probable that most existing TMDLs do not take climate
change considerations into account, and due to the number of TMDLs in existence (~40,000) it is
not feasible to re-open each TMDL with the sole purpose of incorporating climate change
considerations.” In the future, however, EPA will encourage development of TMDLs that
incorporate projected climate impacts and uncertainty, as appropriate.24
Consideration of climate change currently is occurring in a few TMDLs, including Vermont’s
phosphorus TMDL for Lake Champlain. A TMDL is required for Lake Champlain because
phosphorus concentrations in many segments of the lake are higher than levels allowed in
Vermont water quality standards. The states of Vermont and New York jointly developed a
21 U.S. Environmental Protection Agency, “Clean Water Act Section 303(d): Notice of Call for Public Comment on
303(d) Program and Ocean Acidification,” 75 Federal Register 13537-13540, March 22, 2010.
22 Denise Keehner, Director, EPA Office of Wetlands, Oceans and Watersheds, memorandum, “Integrated Reporting
and Listing Decisions Related to Ocean Acidification,” November 15, 2010, p. 4.
23 U.S. Environmental Protection Agency, Global Change Research Program, National Center for Environmental
Assessment, Implications of Climate Change for Bioassessment Programs and Approaches to Account for Effects,
Preliminary Draft, EPA/600/R-11/036A, March 2011, p. 7-1, http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=
233810. EPA expected to issue a final report in mid-2011 but has not done so.
24 U.S. Environmental Protection Agency, National Water Program 2012 Strategy: Response to Climate Change,
Public Comment Draft, March 2012, p. 51, http://water.epa.gov/scitech/climatechange/upload/
NWP_Draft_Strategy_03-27-2012.pdf.
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phosphorus TMDL, which EPA approved in 2002. However, EPA’s approval of the TMDL was
challenged in a federal lawsuit, which asserted a variety of flaws, including insufficiently
stringent wasteload allocations of pollutants for point sources coupled with a lack of reasonable
assurances that nonpoint source reductions would occur; an inadequate margin of safety;
inadequate specificity of the stormwater component of the wasteload allocations; and failure to
consider water resource effects associated with documented and predicted climate change.25
In April 2010, EPA signed a settlement agreement with the environmental plaintiffs, and in
January 2011, the agency reconsidered its previous approval of the Lake Champlain TMDL and
disapproved the Vermont portion. After re-reviewing the 2002 TMDL, EPA concluded that two of
the four contested elements are not consistent with EPA regulations and guidance available at the
time of TMDL approval: margin of safety, and reasonable assurance. EPA found the two other
elements of the complaint—the stormwater component, and climate change considerations—to be
consistent with then-current rules and guidance.
Under section 303(d)(2) of the CWA, upon disapproval of a TMDL, EPA must establish a new
TMDL to implement applicable water quality standards, and EPA has begun a new phosphorus
TMDL for the impaired Vermont segments in Lake Champlain. EPA informed the state of
Vermont that, in doing so, it may refine several aspects of the TMDL, not just the components
that were determined to be inadequate. Although EPA did not reject the challenged climate
change considerations in the 2002 TMDL, apparently they are being addressed now: one
component of preparing the TMDL is a study of potential effects of climate change and
phosphorus loads to Lake Champlain. EPA expects to prepare the TMDL for public comment in
late 2012 or early 2013.26
Multi-Jurisdiction TMDLs
For some time, EPA has encouraged states to develop TMDLs using a watershed approach,
recognizing that, where multiple impaired segments are clustered within a watershed, it
frequently is more efficient to organize restoration activities across the watershed, instead of
doing TMDLs for individual stream segments. One of the first states where this approach was
used is Montana, but it is also reflected in other locations. In cases where the watershed spans
more than one state, TMDLs have been developed jointly or in coordination by several states.
Beyond the expected challenges of TMDL development in a single stream segment (e.g., data,
resources, scientific uncertainties), these multi-jurisdiction TMDLs present additional challenges
(e.g., differing priorities, institutional coordination).
• Several states have developed statewide TMDLs for a single pollutant, such as
Minnesota’s mercury TMDL (described above). Other states (e.g., Florida and
North Carolina) are developing statewide TMDLs for mercury-impaired waters.
Several states also have developed statewide bacteria TMDLs (Rhode Island,
Connecticut, New Hampshire, and Vermont). New Hampshire has developed a
statewide chloride TMDL.
• Because air deposition from outside a single region is a prominent source of
mercury impairments, many mercury TMDLs are being developed on a multi-
25 Conservation Law Foundation v. U.S. Environmental Protection Agency, No. 2:08-cv-00238wks (D. Vt. 2008).
26 http://www.epa.gov/region1/eco/tmdl/pdfs/vt/LakeChamplainTMDLDevelpmtProcess.pdf.
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jurisdiction basis, including the six-state Northeast Regional Mercury TMDL
discussed above.
• New York and Connecticut developed TMDLs with measures needed to attain
water quality standards for dissolved oxygen in Long Island Sound. The TMDLs
require wastewater treatment plants and other point sources in both states to
reduce nitrogen discharges that contribute to the Sound’s water quality
impairment.
• Water quality monitoring data show that approximately half of the length of the
Ohio River (475 miles) is now listed as impaired for contact recreational use. As
a result, a bacteria TMDL is now under development for the entire river due to
the diverse sources that contribute to impairments, including municipal sewer
overflows, animal feedlots, textile and pulp mills, as well as nonpoint sources
such as leaking septic systems and land application of manure. Two EPA regions,
the six states along the river, and the Ohio River Valley Water Sanitation
Commission (ORSANCO) are participating in the TMDL.
• In 2010, EPA approved a TMDL developed by the Washington Department of
Ecology to address nutrient enrichment problems which have caused algae
blooms and low dissolved oxygen levels in Lake Spokane. The TMDL applies to
a 63-mile stretch of the Spokane River from the Idaho-Washington border to the
lake. It is one of the first TMDLs to coordinate point source reductions across
state boundaries; it includes cross-boundary wastewater and stormwater sources
in Idaho, because the Spokane River originates in that state, and modeling
determined that those point sources contribute to water quality impairments in
the watershed in Washington. Among the challenges for Washington and EPA
was developing a TMDL with equitable allocations for dischargers in Washington
and Idaho, one that would not call for disproportionate pollutant reductions in
either state.27
The largest multi-jurisdictional TMDL, for the Chesapeake Bay watershed, is discussed next.
Chesapeake Bay TMDL
One TMDL that touches on several of the issues discussed above and that has drawn considerable
attention and controversy, including from Members of Congress, was developed by EPA for the
64,000-square-mile Chesapeake Bay watershed.
Despite several decades of activity by governments, the private sector, and the general public,
efforts to improve and protect the Chesapeake Bay watershed have been insufficient to meet
restoration goals. Although some specific indicators of Bay health have improved slightly or
remained steady recently (such as blue crabs and underwater bay grasses), others remain at low
levels of improvement, especially water quality. Overall, the Bay and its tributaries remain in
poor health, with polluted water, reduced populations of fish and shellfish, and degraded habitat
and resources. The primary pollutants causing impairments are nutrients (nitrogen and
27 Michael A. Bussell, Director, Office of Water & Watersheds, U.S. EPA Region 10, letter to Kelly Susewind,
Washington Department of Ecology, “Approval of the Spokane River Dissolved Oxygen TMDLs.” May 10, 2010, p.
19, http://www.epa.gov/region10/pdf/tmdl/spokane_tmdl_approval_may2010.pdf.
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phosphorus) and sediment discharged from multiple urban, suburban, and rural sources around
the Bay.
In May 2009, President Obama issued an executive order that declared the Bay a “national
treasure” and charged the federal government with assuming a strong leadership role in restoring
the Bay.28 The executive order established a Federal Leadership Committee for the Chesapeake
Bay to develop and implement a new strategy for protecting and restoring the Chesapeake region.
The resulting strategy, which was released in May 2010, launched major specific environmental
initiatives to establish new clean water regulations on stormwater discharges and pollution
discharges from animal feedlots in the Bay watershed, put new agricultural conservation practices
on farms in the region, and restore land and water habitat.29
A central feature of the overall strategy is EPA’s establishment of a TMDL for Chesapeake Bay,
which was necessitated because the Bay states’ previous restoration efforts were insufficient to
attain water quality standards. Under a consent decree resolving litigation over impairment of Bay
waters, EPA was required to establish a Chesapeake Bay TMDL no later than May 1, 2011.30 EPA
issued the TMDL on December 29, 2010.
The Chesapeake Bay TMDL—which is actually divided into three separate TMDLs—is the
largest single TMDL developed to date. It addresses all segments of the Bay and its tidal
tributaries that are impaired from discharges of nitrogen, phosphorus, and sediment, with a goal
of having TMDL implementation measures in place by 2025. Nitrogen and phosphorus are
considered the main contributors to poor Bay water quality because, in excess amounts, they spur
algae blooms, which block sunlight critical to underwater grasses that support crabs, fish, and
waterfowl. When the algae die, they sink to the bottom and decompose in a process that depletes
the water of oxygen, creating so-called dead zones. Sediment also depletes water of oxygen. To
meet the TMDL goals, the amount of nitrogen entering the Bay needs to be reduced by 75.39
million pounds a year, phosphorus needs to be cut by 14.55 million pounds, and sediment needs
to be reduced by 3.7 million tons from 2009 levels. The TMDL allocates needed reductions of
these pollutants to all jurisdictions in the watershed. Detailed plans identifying specific reductions
are to be developed by the seven jurisdictions located in the Chesapeake Bay watershed in
Watershed Implementation Plans (WIPs).31
As part of the TMDL process, states are to prepare WIPs in three phases identifying specific
reductions and control measures to achieve needed pollutant reductions from point sources (i.e.,
industrial and municipal facilities and large animal feeding operations) and nonpoint sources (i.e.,
farms and forests). The WIPs are part of the accountability framework for the Bay TMDL. Phase
I WIPs were developed in December 2010. They generally outlined the types of controls and best
management practices (BMPs) that will be utilized to meet the first major goals of the TMDL:
that 60% of needed practices to achieve water quality standards will be in place by 2017. Each of
the states’ plans is different and reflects the states’ choices regarding localized identification of
needed controls and BMPs. EPA is now reviewing the Phase II WIPs, which describe how the
jurisdictions will work with specific localities over the next five years to reduce sources of
28 Executive Order 13508, “Chesapeake Bay Protection and Restoration,” 74 Federal Register 23099-23104, May 15,
2009.
29 For information, see http://www.chesapeakebay.net/news_federalstrategy.aspx?menuitem=51207.
30 Fowler v. U.S. EPA, Case No. 1:09-CV-00005-CKK (D.D.C.), May 10, 2010.
31 New York, Pennsylvania, Maryland, Delaware, Virginia, West Virginia, and the District of Columbia.
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impairment. The Bay jurisdictions are to submit Phase III WIPs by 2017, including any
modifications needed to meet the 2025 goal of having in place 100% of practices needed to
achieve the nutrient reduction targets.
The use of WIPs as part of the restoration strategy provides states flexibility to determine the mix
of specific controls they deem appropriate to meet the overall reduction goals. EPA fully expects
that the jurisdictions will meet commitments in the WIPs, but the agency also identified a number
of potential “backstop” actions available to it under the CWA if a state fails to do so, including
expanding permit coverage to currently unregulated sources, requiring net improvement offsets,
conditioning EPA grants, or increasing federal enforcement in the watershed. These CWA
backstop authorities are always available to EPA, but EPA’s use of them in the Chesapeake Bay
TMDL has been very controversial. It also marks a change from the historic nature of Bay
restoration, which was based primarily on stakeholder agreements.32 EPA’s review of the WIPs
has led to discussions with each jurisdiction to resolve certain issues, such as providing
reasonable assurance that allocation targets will be achieved. EPA’s approval of the Phase I WIPs
included certain backstops for New York, Pennsylvania, and West Virginia.33
The Chesapeake Bay TMDL has a number of novel elements. For example, building on a 2009
voluntary agreement by the Bay states, the TMDL requires the jurisdictions to commit to and
report on short-term milestones every two years to help government and the public assess
progress in implementing cleanup plans. Federal and state officials evaluated progress under the
first two-year milestone goals, which were to be reached by the end of 2011, and concluded that
in general, states have made significant overall progress and accelerated nutrient reduction
efforts, but that improvements are still needed in many areas. The mixed findings were not
unexpected. A review by environmental groups for a subset of important pollution controls found
that each state was ahead of schedule in implementing some actions, such as nutrient reduction
from wastewater treatment plants, but behind in others, such as implementing agriculture
conservation management plans.34 The first milestones under the TMDL were submitted by states
in January 2012, and they must be attained by the end of 2013.
The TMDL also reflects the view that nutrient trading can be a promising strategy for meeting
nutrient load limits in a cost-effective way. Under this market-based strategy, sources such as
municipal wastewater and industrial facilities achieve their individual load limits by purchasing
load reductions from other sources such as farmers for a lower cost than if the point source were
to install technology on-site. Three states in the Bay watershed (and a number of other states
outside the region) have initiated nutrient trading programs, but little implementation has
occurred. In the Bay TMDL, EPA supports (but does not mandate) trading to meet the plan’s
nutrient reduction targets and to account for and manage new or increased loadings in the future,
and each of the Bay jurisdictions included nutrient trading in its Phase II WIP.
32 U.S. Government Accountability Office, Chesapeake Bay Restoration Effort Needs Common Federal and State
Goals and Assessment Approach, GAO-11-802, August 2011, p. 10.
33 In New York, EPA required installation of biological nutrient removal at all wastewater treatment plants in the Bay
watershed. In Pennsylvania, EPA moved 50% of the state’s stormwater allocation into wasteload allocation, meaning
that the state likely will have to regulate those stormwater sources through MS4 permits. In West Virginia, EPA shifted
75% of the state’s animal feeding operation (AFO) load into wasteload allocation, meaning that sources could
potentially be subject to state or federal CWA permits as necessary to protect water quality if West Virginia does not
achieve reductions in agricultural loads from nonpoint sources, as identified in the WIP.
34 Chesapeake Bay Foundation and Choose Clean Water, “2011 Milestone Analysis Shows Progress,” July 9, 2012,
http://www.cbf.org/page.aspx?pid-3815.
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Many supporters believe that trading has the potential to result in substantial overall cost savings,
but actual predictions depend on numerous considerations and uncertainty (e.g., required trading
ratios, potential tradeable loads, geographic scope of trading, transaction costs). Trading is also
seen as a means of encouraging agriculture’s participation in Bay restoration, since it has the
potential of generating new revenue for the agricultural sector (since a point source may pay a
farmer to reduce pollutants that the point source would otherwise have to control). It is generally
believed that installing measures to control agricultural sources of nutrients is more cost-effective
than, for example, urban nonpoint source practices such as street sweeping or installing urban
forest buffers.35 To support these types of efforts, USDA awarded $2.35 million to five projects in
FY2012 to promote water quality trading in the Chesapeake Bay watershed. The supported
projects are intended to help completion of state water quality market rules and organizations
needed to carry out trading between point sources and farmers and ranchers. At the same time,
some observers are cautious about the role of water quality trading in restoring impaired waters.
One recent assessment of nutrient trading in the Bay watershed summarized both positive aspects
of nutrient trading—such as potential to use market forces and increase stakeholder support—and
negative aspects—trading to reduce water pollutants is technically complicated, interstate trading
is hindered by differing state requirements, and verifying results is difficult.36
EPA’s TMDL and the overall federal Bay restoration strategy under the executive order are
controversial with a number of groups that are concerned about the likely mandatory nature of
many of EPA’s and states’ upcoming actions. A major concern is that the strategy will be very
costly to implement and will hamper the region’s economic recovery. Critics point out that EPA
has not prepared a cost-benefit analysis of restoring the watershed. EPA is now preparing such an
analysis, based on the Phase I WIPs, and expects to complete it by the end of 2012. Estimating
benefits is more complicated than estimating costs because of the difficulty of monitoring and
verifying results, according to EPA.
Implicit in much of the criticism of the Chesapeake Bay TMDL is concern that EPA will use it as
a model for developing similar large-scale TMDLs in other locations. As previously described,
EPA has developed and approved a number of multi-state TMDLs (e.g., the Northeast Regional
Mercury TMDL), but some observers worry that what they view as an aggressive and inflexible
TMDL strategy for the Chesapeake Bay will be replicated for other waterbodies.
Legal challenges were brought by agricultural and home builder groups, who argue that EPA has
exceeded its CWA authority (for example, by imposing detailed pollutant allocations and using
backup authority to strengthen WIPs) and impinged on the responsibilities of states to assign
pollution reductions to individual sources.37 They also question the science and accuracy of
computer models that EPA used in setting overall pollution limits. EPA contends that
development of the TMDL was well within its authority under the CWA, and the agency disputes
that it overrode state authority, noting that states were fully involved in the TMDL development
process. Several environmental groups and municipal water utility groups have intervened on
EPA’s side in the litigation.
35 RTI International, Nutrient Credit Trading for the Chesapeake Bay, An Economic Study, prepared for the
Chesapeake Bay Commission, May 2012.
36 Willamette Partnership, Pinchot Institute for Conservation, and World Resources Institute, In it Together: A How-To
Reference for Building Point-Nonpoint Water Quality Trading Programs, Case Studies (Part 3 of 3), July 2012, pp. 32-
44.
37 American Farm Bureau Federation and Pennsylvania Farm Bureau v. U.S. EPA, Case No. 11-cv-0067 (M.D. Pa.).
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Environmental activists have expressed support that the federal government is finally asserting a
leadership role to restore the Bay and have endorsed legislation that would codify requirements of
the Bay TMDL in the Clean Water Act, while authorizing grants and other assistance for
implementing required measures. Companion bills to do so were introduced in the 111th Congress
(S. 1816 and H.R. 3852), but no legislation was enacted. The House Agriculture Committee also
approved separate legislation in the 111th Congress (H.R. 5509) that would have authorized an
expanded role for the Department of Agriculture in Chesapeake Bay restoration, to counter EPA’s
role in the TMDL. Legislation similar to H.R. 5509 has been introduced in the 112th Congress
(H.R. 4153). Congress has shown interest in the impact of the plan on agriculture through
oversight hearings by the House Agriculture Subcommittee on Conservation, Energy, and
Forestry (on March 16 and November 3, 2011).
Outside Assessments of the TMDL Program
Over the last decade, several assessments have recommended ways to strengthen the TMDL
program. One Government Accountability Office (GAO) report examined whether available
water quality data are sufficient to allow state officials to make key decisions about activities such
as identifying waters that do not meet water quality standards and developing strategies to address
those waters. Water quality data are so limited, particularly data for nonpoint sources, that many
fear that TMDL decisions will be based on unsound information and will impose unneeded or
inappropriate control mandates, according to GAO. Inconsistent monitoring, data collection, and
listing procedures used by states to identify impaired waters have hindered efforts to develop
effective TMDL programs, GAO found.38
In 2002, GAO issued a related report that examined the different approaches used by states to
identify impaired waters. Some of the approaches have no appropriate scientific basis, GAO said,
and states apply a range of quality assurance procedures to ensure the quality of data used to
make impairment decisions. GAO concluded that, because of inconsistencies in states’
approaches to identifying impaired waters, the information in EPA’s database of impaired waters
is of questionable reliability, and EPA cannot reliably tally the number of TMDLs that must be
completed nationwide.39
EPA’s responses to both reports are reflected in the Integrated Report guidance in place since
2004 (see “Administrative Developments”). It provides guidance on how states can document the
scientific and technical rationale for categorizing their waters, and it lists key elements that must
be included in states’ descriptions of their methodologies. In addition, in order to encourage a
long-term process of incremental improvement in state water monitoring programs, EPA
published a document recommending the basic elements of such a program.40
Following EPA’s controversial revisions of the TMDL program regulations in 2000 (which were
subsequently withdrawn in 2003), the agency’s FY2001 appropriation bill, P.L. 106-377, required
a study by the National Academies of Sciences (NAS) on the scientific basis of the program. The
38 U.S. General Accounting Office, Key EPA and State Decisions Limited by Inconsistent and Incomplete Data,
RCED-00-54, March 14, 2000.
39 U.S. General Accounting Office, Inconsistent State Approaches Complicate Nation’s Efforts to Identify Its Most
Polluted Waters, GAO-02-186, January 11, 2002.
40 U.S. Environmental Protection Agency, Elements of a State Water Monitoring and Assessment Program, EPA 841-
B-03-003, March 2003.
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NAS report, issued in 2001, concluded that scientific knowledge exists to move forward with the
program but recommended certain types of changes, such as utilizing iterative, adaptive
implementation and revision, as scientific data and information improve.41 EPA’s review of the
2000 rule after 2001 was at least partly to consider how to respond to those recommendations,
and many of the more recent TMDLs explicitly allow for and anticipate use of adaptive
management techniques.
In 2007, EPA’s Inspector General (IG) reported on TMDL implementation, particularly EPA’s
attention to information and systems to track and evaluate implementation. The IG found that a
lack of information prevents EPA from determining if TMDL implementation activities are
occurring in a timely manner, and the extent to which TMDLs are restoring impaired waters. EPA
tracks specific outcomes—e.g., numbers of TMDLs developed—but not functional results of
water quality improvement. The report noted that EPA has recently taken steps to measure results
and improve program data, including sponsoring studies of TMDL implementation and evaluating
additional results measures. These tasks are challenging, the IG acknowledged, but the report
urged EPA to provide more management direction to improve its ability to assess how well the
program is functioning.
EPA concurred with many of the IG’s conclusions, but responded in part that the agency has only
limited authority to require new post-TMDL monitoring, data tracking, and reporting. The IG had
recommended that EPA report annually on nationwide implementation activities, such as BMPs
completed and inclusion of wasteload allocations in point source discharge permits. EPA said that
“there are substantial cost and logistical implications of reporting annually and nationally on
TMDL implementation and TMDL environmental outcomes. After a point, tradeoffs between
level of effort invested in reporting and actually restoring impaired waters must be made by EPA
and the States.” 42
Factors Affecting Implementation
EPA and other stakeholders frequently point out that TMDLs are not the only approach to
restoring water quality and that TMDLs are sometimes inseparable from the combined effect of
multiple surface water protection program activities. TMDL implementation is only one of
several factors contributing to water quality improvements, and it is likely to be a small
percentage, the agency says. Other factors besides TMDL implementation could influence
whether a waterbody is in attainment with water quality standards, including new monitoring data
or a change in water quality standards, with data showing that the waterbody meets the new
standards.
Further, states point out that there can be advantages and disadvantages of using TMDLs to
address impairments. Some say, for example, that relying on TMDLs is the right approach when
the problem and the source of impairment are unknown, and more scientific evidence is needed to
allocate pollutant reductions. Others say that doing TMDLs for some types of sources (e.g.,
agriculture) provides transparency and assurance to the public about what the state is doing to
41 National Research Council of the National Academies of Science, Water Science and Technology Board, Assessing
the TMDL Approach to Water Quality Management, June 2001.
42 Office of Inspector General of the U.S. Environmental Protection Agency, Total Maximum Daily Load Program
Needs Better Data and Measures to Demonstrate Environmental Results, Report No. 2007-P-00036, September 19,
2007, p. 17.
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improve water quality. But in view of the technical and resource challenges of doing TMDLs, in
some cases, alternative approaches may also be appropriate. For example, a state may lawfully
avoid listing an impaired water as needing a TMDL if it can demonstrate to EPA that other
pollution control programs provide reasonable assurance that water quality standards will be met,
such as imposition of point source permit limits, or state regulations and local ordinances for
nonpoint sources. However, this use of non-TMDL options is a relatively new idea and has been
little used. Some think that alternative approaches are more difficult to achieve than a TMDL.
One approach, in the state of Washington, is called “straight to implementation.” It involves
working directly with landowners, which enables actions to prevent pollution without first
developing a TMDL, especially when the state has clear enforcement authority over all types of
sources, including nonpoint. Also, a TMDL may not be necessary in cases where the source of
impairment is clearly known and control measures and funding are known and available.43
That said, when a TMDL is developed, implementation is a huge gap in the program for several
reasons. First, as noted previously, CWA section 303(d) requires development of a TMDL for
impaired waters but does not require implementation. States’ strategies for implementation vary
widely. A recent survey determined that five states have laws requiring TMDL implementation
plans, either separately after the TMDL is approved or during development of the TMDL. In five
other states, formal implementation plans are not required, but are completed pursuant to state
guidance. In a third category are 15 states that develop implementation plans based on an
unwritten state initiative or they rely on federal guidance. And finally, another 15 states have less
intensively developed implementation plans, which generally are a brief section in the TMDL
report. No information was found for nine states. The survey also examined how states implement
nonpoint source pollutant reductions. It found that 10 states have regulations to address some or
all types of nonpoint source pollution, while most states use incentive-based and voluntary
programs instead of a regulatory approach.44
Second, a number of barriers to TMDL implementation can be identified.45 The most prominent
hindrance is funding. The CWA provides no dedicated funding for TMDL development or for
implementation. Inadequate resources are cited as a problem for BMP implementation for
nonpoint sources, for point source upgrades such as wastewater treatment plants, for abandoned
mine land restoration, for staffing and technical expertise, and for data collection, modeling, and
follow-up monitoring. Technical impediments are a related challenge, such as insufficient
scientific data on the pollutant removal performance of BMPs for nonpoint sources, or inability to
link water quality impacts to sources or causes due to lack of data and understanding of pollutant
fate and transport.
43 See Environmental Law Institute, National Workshop to Advance State TMDL Programs, Final Project Report &
Workshop Proceedings, November 2008, http://www.eli.org/pdf/tmdl/TMDL.FinalReport.pdf. Hereafter, National
Workshop.
44 Virginia Tech University, Biological Systems Engineering Department and the Center for TMDL and Watershed
Studies, State-Specific TMDL Implementation Information, September 2008, http://water.epa.gov/lawsregs/
lawsguidance/cwa/tmdl/upload/2009_09_09_tmdl_results_27_st_imp_info_va_tech.pdf.
45 See, for example, Brian Benham, Rebecca Zeckoski, and Gene Yagow, “TMDL Implementation: Lessons Learned,”
Proceedings: Water Environment Federation TMDL 2007 Conference, pp. 428-442, http://water.epa.gov/lawsregs/
lawsguidance/cwa/tmdl/upload/2009_09_09_tmdl_results_27_st_imp_info_va_tech.pdf; Environmental Law Institute,
State TMDL Program Resource Center, “State TMDL Program Snapshots,” http://www.eli.org/program_areas/Events/
StateTMDLProgramSnapshots.cfm; and National Workshop.
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At the same time, several factors that seem to aid effective implementation also can be identified.
These include active involvement of stakeholders and local and state governments; using a
diversity of approaches to address sources; existence of a watershed plan that is focused on issues
in the watershed and achievable through corrective actions; targeted or phased implementation;
and adequate resources to implement corrective measures, monitor progress, and provide
technical assistance.
Conclusion
After nearly 40 years of implementing the CWA, EPA and states acknowledge that a substantial
portion of the nation’s waters still are impaired or threatened by pollution. The most recent
national inventory of water quality reported that nearly 40% of surveyed water bodies remain too
polluted for fishing, swimming, and other designated uses. Yet those numbers only represent
rivers, streams, and lakes actually surveyed by state monitoring programs—typically about one-
third of all waters. The TMDL assessments developed by states yield more precise water quality
information and identify large numbers of waters requiring additional measures before water
quality standards are attained.
The TMDL program is in a period of transition. Many states are emerging from earlier consent
decree mandates and are increasingly addressing new challenges—for example, more complex
and resource-intensive TMDLs, larger scale impairments, and nonpoint sources. Whether the
program as it now exists is well suited to address some of these problems, such as ocean
acidification or climate change, is debatable. In August 2011, EPA and state program managers
launched discussions of developing new goals for the program. One year later, these discussions
produced a draft “long-term vision” for reforming the process, including allowing states the
option to consider protecting healthy waters, using alternative approaches that incorporate
adaptive management, and integrating TMDLs with other CWA and Safe Drinking Water Act
programs.46
Other than recent oversight hearings on the Chesapeake Bay TMDL, Congress has not shown
active interest in the TMDL program for more than a decade. Some stakeholders, especially
states, believe that several issues present Congress with an opportunity to examine the TMDL
provisions of the CWA. Issues could include integrating TMDLs into a larger clean water
program that considers all steps—from designation of uses to implementation—in order to meet
water quality standards, recognizing and striking a balance between water quality restoration and
pollution prevention, changing focus from point sources to nonpoint sources, and addressing
resource and funding needs.
46 Amena H. Saiyid, “Draft TMDL Plan Focuses on Protecting Waters, Not Just Restoring Impaired Ones,” Daily
Environment Report, August 20, 2012, http://www.bna.com/draft-tmdl-plan-n12884911304/.
Congressional Research Service
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Clean Water Act and Pollutant Total Maximum Daily Loads (TMDLs)
Author Contact Information
Claudia Copeland
Specialist in Resources and Environmental Policy
ccopeland@crs.loc.gov, 7-7227
Congressional Research Service
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