Clean Water Act Section 303(d), List of Water Quality Limited Segments

The Central Coast Water Board is “on cycle” for the 2028 Integrated Report. The data solicitation period ended October 23, 2024. A draft Staff Report is planned for release in the spring of 2027. Please see the heading “2028 303(d) List (In Progress)” below for more details.

Central Coast Water Board staff is proposing some mapping changes/corrections for the 2026 Integrated Report. Please see the heading “2026 303(d) List (In Progress)” below for more details.

The 2024 303(d) List was partially approved by U.S. EPA on December 12, 2024. Please see the heading “2024 303(d) List (Partially Approved)” section below.

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 303(d) 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 303(d) list. The policy requires that Water Boards approve an updated 303(d) list every two years and include public participation. Since the 2020-2022 California Integrated Report cycle, the State Water Board has been administering the public process, including board hearings and development of the integrated report. While the Regional Water Boards play a significant role in the development of the integrated report, the Regional Water Boards no longer conduct individual board hearings and public comment periods. Finally, the 303(d) list is submitted to U.S. EPA for approval.

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). An introductory program fact sheet on the integrated report is available.

Please also see the State Water Board's website regarding the integrated report.

2028 303(d) List (In Progress)

The 2028 Integrated Report is currently in progress. Please visit State Board's website for more information about the 2028 Integrated Report.

2026 303(d) List (In Progress)

The 2026 Integrated Report is currently in progress. Please visit State Board's website for more information about the 2026 Integrated Report. Note that the Central Coast region is "off-cycle" for the 2026 Integrated Report and while no data for the Central Coast region will be included in this cycle, staff is proposing some mapping corrections. These corrections involve spatial changes, name changes/corrections, beneficial use corrections, and station association corrections. Details will be available in the staff report, which will be available Spring 2025.

2024 303(d) List (Partially Approved)

U.S. EPA partially approved the 2024 303(d) list on December 12, 2024. Any outstanding issues (see U.S. EPA’s Public Notice) with the 2024 303(d) list do not have to do with specific listings in the Central Coast region. Please see the State Board's website for more information about the 2024 Integrated Report.

2020-2022 303(d) List

The 2020-2022 303(d) List and Integrated Report was approved by U.S. EPA May 11, 2022. Please visit State Board's website for more information about the 2020-2022 Integrated Report.

Past 303(d) Lists

For information on past 303(d) lists, please visit State Water Board's website under "Integrated Report Cycles."

Questions?

For questions on the California 303(d) list and integrated report, contact Shanta Keeling of the Central Coast Water Board via email at: Shanta.Keeling@waterboards.ca.gov