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.


For more information on TMDLs:

The State Water Resources Control Board (State Board) coordinates the TMDL Program statewide. The State Board's webpage contains addition information regarding the TMDL Program, development of TMDLs, and adopted TMDLs in California.

The U.S. Environmental Protection Agency (USEPA) has a webpage on the Impaired Waters and 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 USEPA covers Arizona, California, Hawaii, Nevada, the Pacific Islands subject to U.S. law, and approximately 140 Tribal Nations. USEPA Region 9's webpage on TMDLs also includes the monitoring, assessment and status of California's 303(d) list and finalized TMDLs.