Central Coast Region - Clean Water Act Section 303(d), List of Water Quality Limited Segments

The State Water Resources Control Board (State Board) adopted the 2024 303(d) List on February 6, 2024. The 2024 303(d) List will be submitted to the U.S. EPA in the Spring of 2024. For more information, including the staff report, factsheets, and an interactive map, please visit the State Board’s website. Please also see the 2024 303(d) List (in progress) section below.

The U.S. EPA approved the 2020-2022 303(d) List on May 11, 2022. For more information, including the staff report, factsheets, and an interactive map, please visit the State Water Board website.

What is the 303(d) List?

Section 303(d) of the federal Clean Water Act requires states to develop, update, and submit to the United States Environmental Protection Agency (U.S. EPA) for approval, a list of waterbodies that are polluted (the 303(d) List). Under Title 40 Code of Federal Regulations (40 CFR) Section 130.7(d)(1), states are required to submit the 303(d) List biennially to the U.S. EPA. In addition to identifying the waterbodies that are not supporting beneficial uses, the List also identifies the pollutant or stressor causing impairment, and establishes a priority for developing a pollution control plan (typically a Total Daily Maximum Load or TMDL) to address the impairment.

How and when does the 303(d) List get updated? And how can I participate?

State Water Board initiates the process to update the 303(d) List by soliciting data and information from the public every two years. Staff at the Regional and State Water Board (Water Boards) consider "readily available data and information,” along with other data (e.g., data submitted directly via the U.S. EPA via the Water Quality Exchange (WQX) or data that cannot be uploaded into CEDEN and needs to be submitted directed via the Integrated Report Upload Portal, etc.) available to the Water Boards, in preparing the updated 303(d) List. Readily available data and information is defined as data and information successfully submitted to the State Water Board via the California Environmental Data Exchange Network (CEDEN). In California, the Water Boards follow the "Water Quality Control Policy for Developing California's Clean Water Act Section 303(d) List" (Listing Policy) when developing updates to the List. This policy describes the process by which the Water Boards comply with the requirements of the Clean Water Act section 303(d) and 305(b) in developing the List. The policy requires that Water Boards approve an updated 303(d) List every two years and include public participation. Finally, the List is submitted to U.S. EPA for approval.

2020-2022 Integrated Report Map

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In addition, pursuant to Clean Water Act Section 305(b), states must prepare a report on the water quality and condition of waters (305(b) Report) to identify whether waters are attaining water quality standards. The 305(b) Report does not require approval. However, U.S. EPA will compile the data from the state 305(b) Reports and transmit the summaries in their "National Water Quality Inventory Report" to Congress.

The Water Boards prepare a single Integrated Report that meets the reporting requirements of CWA sections 303(d) and 305(b).

Please also see the State Water Board’s website regarding the Integrated Report.

2024 303(d) List (In Progress)

The 2024 Integrated Report is currently in progress. Please visit State Board’s website for more information about the 2024 Integrated Report. 

2020-2022 303(d) List (Current Integrated Report)

2020-2022 303(d) List and Integrated Report, U.S. EPA approved May 11, 2022.

Past 303(d) Lists

For information on past 303(d) Lists, please visit State Board’s website under “Integrated Report Cycles.”


For questions on the California 303(d) List and/or Integrated Report contact Shanta Keeling of the Central Coast Water Board via email at: Shanta.Keeling@waterboards.ca.gov

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