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State Water Board/ TMDL

Total Maximum Daily Load Program

Section 303(d) of the federal Clean Water Act (CWA), requires States to identify waters that do not meet water quality standards after applying effluent limits for point sources other than POTWs that are based on the best practicable control technology currently available and effluent limits for POTWs based on secondary treatment. States are then required to prioritize waters/watersheds for total maximum daily loads (TMDL) development. States are to compile this information in a list and submit the list to U.S. EPA for review and approval. This list is known as the 303(d) list of impaired waters (303(d) list).

The State Water Resources Control Board (the State Water Board) and Regional Water Quality Control Boards have ongoing efforts to monitor and assess water quality, to prepare the Section 303(d) list, and to develop TMDLs.

Ambient Monitoring
The State Water Board is developing a new program to monitor the quality of the State's waters. The Surface Water Ambient Monitoring Program (SWAMP) will assess impacts on beneficial uses, the locations of polluted sites, the areal extent of pollution, and trends in water quality.

Section 303(d) List
The State's most recent 303(d) list was approved in 1998. California's current Section 303(d) list contains 509 water bodies, many for multiple pollutants.

Total Maximum Daily Loads (TMDLs)
TMDLs are documents that describe a specific water quality attainment strategy for a water body and related impairment identified on the 303(d) list. TMDLs may include more than one water body and more than one pollutant. The TMDL defines specific measurable features that describe attainment of the relevent water quality standards. TMDLs include a description of the total allowable level of the pollutant(s) in question and allocation of allowable loads to individual sources or groups of sources of the pollutant(s) of concern.

AB 982 (Ducheny)
AB 982 created a new program to reassess or confirm the approaches the State of California has taken to implement Section 303(d). This bill has provided the with an opportunity to carefully review the monitoring approaches, data needed to list sites, and how the State approaches TMDLs. The State Water Board has established a 24-member Public Advisory Group to assist in the evaluation of the State's monitoring and TMDL efforts.