Skip to main content

Annual Combined Sewer Overflow and Consent Decree Reports

King County prepares an annual report on its combined sewer overflow (CSO) control program for the Washington State Department of Ecology (Ecology).

These reports are required under the National Pollutant Discharge Elimination (NPDES) permit for King County’s West Point Treatment Plant in Seattle and WAC 173-245-090.1.

Additionally, King County has an agreement with the U.S. Environmental Protection Agency (EPA) and Ecology called a “consent decree,” which also requires an annual report. The consent decree outlines the planned actions to bring the County’s CSO program into compliance with the federal Clean Water Act (CWA).

The agreement with EPA and Ecology consolidates the two annual reports into one. This report meets the consent decree, state, and federal requirements.


2022 Annual CSO and Consent Decree Report 2022 CSO Annual Snapshot


Report Contents Appendices
1.0 Introduction A Untreated CSO Events, January–December 2022
2.0 Programs to Meet EPA’s Nine Minimum Controls B Treated CSO Events, January–December 2022
3.0 Control Status of CSO Locations C Alki Wet Weather Treatment Station 2022 Annual Report
4.0 CSO Control Measures Currently Underway D Carkeek Wet Weather Treatment Station 2022 Annual Report
5.0 Summary of Rainfall and CSO Events E Elliott West Wet Weather Treatment Station 2022 Annual Report
6.0 Summary of Consent Decree and NPDES Violations in 2022 F Henderson/MLK Jr. Way Wet Weather Treatment Station 2022 Annual Report
7.0 Post-construction Monitoring