skip to main content

Protecting our waters

Doing our part on rainy days
For questions about the King County Protecting Our Waters Program, please contact John Phillips.

Wastewater Treatment Division
King Street Center
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855

Get Directions to our office location in Seattle, Washington.

Real Time Combined Sewer Overflow (CSO) Notification

CSO_Banner_Photo_RIGHT

CSO Control Program Reviews and Plan Updates

King County's CSO program issues two documents for comprehensive review of program success, update and future projects. The reviews and updates are done in approximately five-year intervals.

CSO Control Program Review

Program Reviews are submitted to the King County Executive and Council. The Program Review analyzes the need for CSO control, public involvement, and the relationship of the CSO control program to other county priorities. The control project schedule is verified and, if necessary, reprioritized based on any new information or data.

CSO Control Plan

As a part of the application for renewal of the county's West Point Treatment Plant's National Pollutant Discharge Elimination System (NPDES) permit from the Washington State Department of Ecology, King County submits an update to the CSO Control Plan about every 5 years.

Under Ecology's CSO regulation (WAC 173-245) (external link) CSO Control Plan Updates reviews the achievements of the program over the past five years, commits to the next phase of projects for CSO control for the next NPDES permit phase, and amends the plan for any proposed changes.

You will need a PDF Reader to view these files.

2012 Long-term CSO Control Plan Amendment, October 2012
This plan amendment includes the 2012 CSO Control Program Review Report, as amended by the King County Council, along with the signed legislation approving the 2012 King County Long-term CSO Control Plan Amendment. 
2008 CSO Control Plan Update, June 2008
Table of Contents
Complete document (1.1MB)
King County CSO Public Notification Feasibility Study, July 2007
Letter to Ecology
Complete document (1.8MB)
CSO Control Program Review, April 2006
Table of Contents
Executive Summary
Complete document (1.5MB)
2000 CSO Control Plan Update, June 2000
Table of Contents (121KB)
Complete document (6.1MB)
King County CSO 5-Year Update
Task 4.0, Development of Alternatives, December 1997
Table of Contents (548KB)
Executive Summary (525KB)
Complete document (43MB)
METRO CSO 5-Year Update
Task 5 Report, RWSP System Alternatives,
Supporting CSO Project Descriptions, August 1995
Table of Contents (118KB)
Complete document (21MB)
1995 CSO Control Update, February 1995
Table of contents (113KB)
Complete document (5.2MB)
1986-1991 CSO Control Plan Update, January 1992
Table of contents (59KB)
Complete document (1.7MB)
1988 CSO Control Plan, April 1988
Table of contents (89KB)
Complete document (4.3MB)
1986 Final Supplemental Plan for CSO Control:
Plan for Secondary Treatment Facilities and CSO Control
, Volume 3, July 1986
Table of contents (194KB)
Complete document (6.6MB)

For more information