Section 303(d) of the Clean Water Act requires the identification of waterbodies that do not meet, or are not expected to meet, water quality standards (i.e., impaired waterbodies). The affected waterbody, and associated pollutant or stressor, is then prioritized in the 303(d) List. The Clean Water Act further requires the development of a Total Maximum Daily Load (TMDL) for each listing. The current list, approved by the EPA, is the 2010 303(d) List. The Water Quality Control Policy for Developing California's Clean Water Act Section 303(d) List (Listing Policy) describes the requirements for developing the 303(d) list in California.
In addition to the impaired waterbody list required by Clean Water Act Section 303(d), Clean Water Act section 305(b) requires states to develop a report assessing statewide surface water quality. Both Clean Water Act requirements are being addressed through the 2010 CWA 303(d)/305(b) Integrated Report which will address both an update to the 303(d) list and a 305(b) assessment of statewide water quality. (See "2010 Integrated Report" tab)
In California, the 303(d) list is made up of three of the Integrated Report categories, 4a, 4b, and 5. These categories contain water bodies that have listed pollutants that are still requiring the development of a TMDL, or are being addressed by a USEPA approved TMDL or an action other than a TMDL. Below are the Integrated Report Category Reports that make up the 303(d) list and the Factsheets that contain the supporting information for listing decisions: