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Most King County offices will be closed on Thursday and Friday, Nov. 22-23, 2018, for the Thanksgiving holiday.  
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King County's CSO program issues two documents for a comprehensive review of program successes, updates, 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  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.

2012 CSO Control Plan amendment

In 2012, the King County Council and Executive approved nine recommended alternatives to control overflows that occur at 14 CSO locations in the regional wastewater system. These projects use both natural drainage and traditional infrastructure methods to control CSO outfalls. 

John Phillips
CSO Program Manager