Under CWA section 303(d), states are required to submit to U.S. EPA a list identifying waters within its boundaries not meeting water quality standards (impaired waters) and the water quality parameter (i.e., pollutant) not being met (referred to as the 303(d) List). States are also required to include a priority ranking of such waters, taking into account the severity of the pollution and the impacted beneficial uses, for the development of total maximum daily loads (TMDLs). The Water Quality Control Policy for Developing California's Clean Water Act Section 303(d) List (Listing Policy) provides the requirements for developing the 303(d) List in California.
In addition to the 303(d) List, Clean Water Act section 305(b) requires states to report to U.S. EPA on the overall water quality conditions of their surface waters, not just those that are impaired (this is referred to as the 305(b) Report). Both Clean Water Act section 303(d) and section 305(b) requirements are being satisfied by the 2014 and 2016 California Integrated Report. (See "2014 and 2016 Integrated Report" tab)
Consistent with Section 2 of the Listing Policy, the California 303(d) List is made up of Integrated Report Categories, 4a, 4b, and 5. These categories contain water bodies that have listed pollutants that still require the development of a TMDL, are being addressed by a U.S. EPA approved TMDL, or a U.S. EPA approved 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: