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San Diego Region - Total Maximum Daily Loads (TMDLs)


The Total Maximum Daily Load (TMDL) program is required under Clean Water Act (CWA) Section 303(d). There are streams, lakes and coastal waters within this Region that do not meet certain water quality standards. CWA Section 303(d) addresses these waters by requiring states to identify the waters and develop total maximum daily loads (TMDLs) for them. A TMDL is a quantitative assessment of water quality problems, contributing sources, and load reductions or control actions needed to restore and protect bodies of water. The TMDL approach does not replace existing water pollution control programs. It provides a framework for evaluating pollution control efforts and for coordination between federal, state and local efforts to meet water quality standards. TMDLs are adopted as amendments to the Basin Plan. More information is available in the TMDL Program Fact Sheet.

TMDLs Adopted by Regional Board

TMDLs Adopted by Regional Board Using Alternative Approach

TMDLs in Process


For more information on TMDLs:

The U.S. Environmental Protection Agency has a webpage on the TMDL Program under section 303(d) of the Clean Water Act. Information on this page includes: status of 303(d) lists, TMDL program documents, TMDL Federal Advisory Committee, TMDL lawsuit information, and other links.

Region 9 of the EPA covers Arizona, California, Hawaii, Nevada, the Pacific Islands subject to U.S. law, and approximately 140 Tribal Nations. EPA Region 9's webpage on TMDLs also includes the status of California's 303(d) list and several finalized TMDLs.