Claudia
Copeland
Specialist in Resources and Environmental Policy
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.
Date of Report: September 21, 2012
Number of Pages: 22
Order Number: R42752
Price: $29.95
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