skip to main content

Combined Sewer Overflow Control

By reducing combined sewer overflows into local water bodies, King County is protecting public health and the environment.
For questions about the King County CSO Control Program, please contact Karen Huber.

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 CSO Notification

King County's Approved Long-term CSO Control Plan Amendment

Download plan amendment, program review and supporting technical documents

You will need a PDF Reader to view these files.

2012 Long-term CSO Control Plan Amendment, October 2012

2012 King County 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. This Plan has been submitted to the USEPA and the WA Dept of Ecology. The plan documents King County’s review of its CSO Control Program, which was conducted in accordance with policies and guidelines in the 1999 Regional Wastewater Services Plan (RWSP).

2012 King County Long-term CSO Control Plan Amendment (17.9 MB), October 2012

Back to top of page

King County Executive's Recommended CSO Control Plan, June 2012

King County Executive's Recommended Combined Sewer Overflow Control Plan

The King County Executive’s plan is a summary of the 2012 Long-term CSO Control Plan Amendment approved by the King County Council on September 17, 2012 (view news release). It reflects community values, concerns, and preferences expressed throughout a three year-long comprehensive review of the CSO Control Program. Completion of the nine CSO control projects will meet federal and state regulations by controlling all King County CSO locations to no more than one overflow per year on average at each location.

King County Executive's Recommended CSO Control Plan (2.8MB), June 2012

Back to top of page.

Supporting technical documents

Technical Memorandums supporting the 2012 CSO Control Program Review Report

The following technical memorandums (TMs) are referenced in the 2012 Long-term CSO Control Plan Amendment.

Back to top of page.

Approval of King County's 2012 Combined Sewer Overflow (CSO) Control Program Review Report, EPA, March 7, 2013

Print copies of these materials

Print copies of the plan and related technical memorandums are available on request.

Related information 

Recommended CSO Control Projects
A map of approved CSO control projects
 as presented in the plan.

 CSO Control Program Library