303(d) Information and Map
Section 303(d) of the Clean Water Act (CWA) establishes that
states are to list (the 303(d) list) waters for which technology-based limits
alone do not ensure attainment of applicable water quality standards (WQS). The 303(d) list is to be submitted by the states to EPA on April 1
of each even numbered year. The 303(d) list includes priority rankings set
by the state for the listed waters.
Once the impaired waters are identified, Section 303(d) requires
that the states establish total daily maximum loads (TMDLs) that will meet water
quality standards for each listed water, considering seasonal variations and a
margin of safety (MOS) that accounts for uncertainty.
EPA's regulations for implementing Section 303(d) can be found
in the Codified Federal Register (CFR) for Water Quality Planning and Management
at 40 CFR Part 130. The regulations define terms used in Section 303(d)
and otherwise interpret and expand upon the statutory requirements.
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