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The 303(d) List of Impaired Water Bodies


The Federal Clean Water Act (CWA) gives States the primary responsibility for protecting and restoring surface water quality. Under the CWA, States that administer the CWA must review, make necessary changes, and submit the CWA section 303(d) list to the U.S. Environmental Protection Agency (U.S.EPA). CWA Section 305(b) requires each State to report biennially to U.S.EPA, on the condition of its surface water quality. The U.S.EPA has issued guidance to States which requires the two reports to be integrated. For California, this combined report is called the California 303(d)/305(b) Integrated Report.

For 303(d), State and Regional Water Boards assess water quality monitoring data for California’s surface waters every two years to determine if they contain pollutants at levels that exceed protective water quality standards. Water body and pollutants that exceed protective water quality standards are placed on the State’s 303(d) List. This determination in California is governed by the Water Quality Control Policy for developing California’s Clean Water Act Section 303(d) List. U.S.EPA must approve the 303(d) List before it is considered final.

Placement of a water body and pollutant that exceeds protective water quality standards on the 303(d) List, initiates the development of a Total Maximum Daily Load (TMDL). In some cases other regulatory programs will address the impairment instead of a TMDL.

For 305(b) Report, State and Regional Water Boards place the water body segment that were assessed into one of U.S.EPA’s five Integrated Report beneficial use report category. For this assessment available data are used to evaluate most common beneficial uses including aquatic life, drinking water supply, fish consumption non-contact recreational, and swimming.

California has been developing 303(d)/305(b) Integrated Reports every two years since 1976. Most of these reports are available in electronic format on the State Board's Water Quality Assessment web page.

Current Status of 2012 303(d) Listing Process

The State Board, in coordination with Regional Water Board staff and U.S. EPA, has been assessing the data submitted by all interested parties in response to the notice of solicitation dated May 24, 2010. Pursuant to the State Board's commitment to making the Integrated Report process more efficient and submittals to U.S. EPA more timely, a new strategy has been developed for the listing process. The strategy includes establishing three groups, each consisting of three Regional Water Boards and submitting an Integrated Report for one group per listing cycle. Consequently, the 2012 Integrated Report will consist solely of data submitted for the North Coast region, the Lahontan region, and the Colorado River Basin region. The 2014 Integrated Report will consist of data submitted for the Central Coast region, the Central Valley region, and the San Diego region. Finally, the 2016 Integrated Report will consist of data for the San Francisco Bay region, the Los Angeles region, and the Santa Ana region. Regional Boards may still examine high priority listing and de-listing decisions even if they are "off-cycle" (see below for proposed de-listings).

Due to the volume of data received during the 2010 data solicitation period, the State Water Board will not solicit additional data until all of the current data are assessed and migrated to the California Water Quality Assessment Database (CALWQA) for Regional Water Board listing and de-listing recommendations. However, data will be accepted into the California Environmental Data Exchange Network (CEDEN) immediately so it can be assessed during future listing cycles. There are four reigonal CEDEN data centers that can assist with uploading data.

Proposed De-Listings

Muir Beach Delisting Project:
The San Francisco Bay Regional Water Quality Control Board approved at its May 14, 2014, meeting a proposal to remove Muir Beach from the Clean Water Act Section 303(d) list of impaired water bodies for impairment by indicator bacteria. Muir Beach is now on the list for indicator bacteria resulting in impairment of water contact recreational use. The staff report detailing recent water quality assessments and staff’s interpretation of the assessments and related information can be found below. This proposed delisting is expected to be included in the Integrated Report submitted to U.S. EPA for the 2016 listing cycle. 

Napa River and Sonoma Creek Delisting Project:
The San Francisco Bay Regional Water Quality Control Board approved at its February 12, 2014 meeting a proposal to delist Sonoma Creek for nutrients resulting in excessive algae growth and to remove this water body from the EPA 303(d) list. The staff report detailing recent water quality assessments, lines of evidence, and interpretation of data are provided below. This de-listing will be included in the Integrated Report submitted to U.S. EPA for the 2014 listing cycle. See the Napa River Nutrients and Sonoma Creek Nutrients project pages for more information.

Past 303(d) Lists (2010 List)

Evaluation of Water Quality Conditions for San Francisco Bay Region. Proposed Revisions to federal Clean Water Act Section 303(d) List of Impaired Waters.

The last complete 303(d) list for the San Francisco Bay Region was completed in 2010. View and query the final 2010 303(d) list on the State Board website. For information about the San Francisco Regional Water Board process in preparing the 2010 303(d) list, see the documents below.


Past 303(d) Lists (2006 List)