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Performance Report

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The California Water Boards' Annual Performance Report - Fiscal Year 2011-12


MESSAGE:  TMDLs have been adopted to address 1,070 impaired water body listings, but more than 1,900 listings still need to be addressed statewide.

Implementation of adopted TMDLs is now underway. Implementation outcome status has been evaluated for about 19% of adopted TMDLs.
Number of TMDLs Adopted to date
Number of Listings Addressed by TMDLs 1,070
Number of Listings Addressed by other actions 516
Total Number of Listings Remaining 1,940

Region TMDLs Adopted Implementation Outcome Status Assessed % Assessed Conditions Improving Data Inconclusive Improvement Needed TMDL Achieved

TMDL OUTCOME REPORTS (Click on Map to select region, click on Thumbnail to Enlarge)

Region 1 Region 2 Region 3

Region 4 Region 5 Region 6

Region 7 Region 8 Region 9


Under Section 303(d) of the Clean Water Act, California required to develop a list of waters that do not meet water quality standards. This list is often referred to as the 303(d) list. The Clean Water Act further requires development of action plans, called Total Maximum Daily Loads (TMDL), to improve water quality. As of July 1, 2012, the State and Regional Boards have adopted approximately 180 TMDLs addressing more than 1,000 impaired waterbody listings. In California, TMDLs are incorporated into Basin Plans and include a program of implementation to ensure actions are put in place to reduce pollutant sources and ultimately resolve water quality problems. In effect, TMDLs are performance based water quality management plans. TMDL implementation schedules; however, can range from years to decades depending on the type of pollution, the complexity of the TMDL, and the physical setting of the waterbody being addressed. The progress reports presented above explain the implementation status and/or the water quality outcomes resulting from implementation of specific TMDLs. Each TMDL has a different program of implementation, a different schedule, and usually different challenges, therefore, the water quality outcomes vary.



Adoption of TMDLs can be a resource intensive and a time consuming process. Once adopted, TMDLs must be implemented to provide water quality benefits. As indicated above TMDLs are usually incorporated into a Regional Water Board Basin Plans, which in turn require development of a program of implementation for achieving the TMDL, including a description of the nature of actions that are necessary to achieve water quality objectives, time schedules for the actions to be taken, and a description of surveillance to be undertaken to determine compliance with objectives. This measure tracks TMDL implementation progress and shows how TDML implementation affects water quality.



  • Data Definitions: TMDL project: A TMDL project is a planned strategy to reduce pollution in an impaired water body so that its water quality standards are met. A TMDL project addresses one or more pollutants for a given waterbody or segment of waterbody (known as TMDL listings). TMDL listing: A TMDL listing refers to a pairing of a waterbody and a pollutant that is responsible for the impairment (i.e., each water body-pollutant combination is called a listing). A given waterbody is impaired due to the presence of one or more pollutants (each called a listing) and a TMDL project may address more than one listing. . The extent of each listing varies among Regional Boards. The current TMDL projects and listings are documented in the Water Boards' 2010 Clean Water Act Section 303(d) list. Listing Underway: Listings remaining to be addressed by TMDL projects underway.
  • References: Information on the Water Boards' TMDL activities



Impaired Water (Listing)
An impaired waterbody is one that does not meet the water quality objectives established to protect the beneficial uses of the water due to the presence of one or more pollutants. Such waters are identified on the Water Boards' Clean Water Act Section 303(d) list.

A pollutant is a waste or substance that, at certain levels, can cause waterbody impairment. The monitoring programs of the Water Boards and others provide information on the levels of pollutants in the State's waters.

Implementation Outcome Status Assessed
A summary report has been prepared showing the outcome of implementing TMDLs that have already been adopted. It is important to note that Regional Boards may be taking steps to implement TMDLs (e.g., incorporating TMDL requirements into permits, reviewing water quality data, etc.) for TMDLs for which outcome status reports have not yet been developed.


TMDL Achieved/Waterbody Delisted
Water quality data or other information demonstrate that final water quality targets are consistently met; OR The waterbody has been removed from the 303(d) list.
Conditions Improving
Water quality data and/or other indicators demonstrate improvement; ANDThe final water quality targets not consistently being met; AND
The overall schedule for achieving the TMDL has not yet elapsed.
Data Inconclusive
Not enough data (of acceptable quality) has been collected to demonstrate that the TMDL targets are consistently met; OR
Variability in data do not permit a determination in water quality trends (positive or negative).
Improvement Needed
Final water quality targets not consistently met; AND
The overall schedule for achieving the TMDL has elapsed; OR
In Water Board staff judgment, water quality data or other indicators suggest that TMDL targets will not be met by the time the overall schedule for achieving the TMDL has elapsed indicating a need to either revise the TMDL or take other regulatory action; OR
In Water Board staff judgment, water quality data and/or other indicators demonstrate that water quality is either declining or not improving.

( Page last updated:  8/20/13 )