Identifying and Listing Impaired Waters under the Clean Water Act

The Clean Water Act (CWA) requires states to identify waters that do not or are not expected to meet applicable water quality standards with current pollution control technologies alone.

Since 1992, EPA has issued program guidance on the 303(d) listing and reporting process to help states prepare and submit to CWA section 303(d) reports. In 2002 the Agency encouraged states to merge the 305(b) report and the 303(d) report. States are allowed to report on all their assessed water under section 305(b) and the list of those that are impaired in a single integrated report. Integrated Report Guidance (IRG) is issued biennially to support states in making listing decisions and reporting on the conditions of their waters.

Assessing, Listing and Reporting Requirements Pursuant to Sections 303(d), 305(b) and 314 of the Clean Water Act

Integrated Reporting

• Integrated Reporting Guidance

Section 303(d) Program Implementation Documents

• Memorandum: Milestone Template to Facilitate State-EPA Dialogue to Achieve Timely Impaired Waters Action under CWA Section 303(d) (pdf) (1.85 MB, 01/14/2021)
• Listing Waters Impaired by Atmospheric Mercury, March 8, 2007
• Clarification of the Use of Biological Data and Information in the 2002 Integrated Water Quality Monitoring and Assessment Report Guidance, March 26, 2002
• National Clarifying Guidance For 1998 State and Territory Section 303(d) Listing Decisions, August 17, 1997
• Guidance for 1994 Section 303(d) Lists, November 26, 1993

Retrospective Review of the Section 303(d) Program

• Final Report: Reducing Reporting Burden under Clean Water Act Sections 303(d) and 305(b), September 27, 2013