King County Wastewater Discharge Permits
from municipal wastewater facilities

King County discharges treated wastewater under permits issued by the Washington State Department of Ecology (Ecology). Ecology administers the National Pollutant Discharge Elimination System (NPDES) permits (external link) under authority delegated to the department by the U.S. Environmental Protection Agency. These permits outline the conditions under which a municipality can discharge treated wastewater. Learn more about Wastewater Discharge Permits in Washington State (PDF, external link).

King County has four NPDES permits for discharging treated wastewater from its regional wastewater system:

NPDES Permit Description

Permit no. and expiration date

Download permit*

West Point Treatment Plant, Seattle, WAThe West Point permit covers the operation of the West Point Treatment Plant in Seattle, the combined sewer overflow (CSO) system, the CSO treatment facilities including Alki, Carkeek, Elliott West, Henderson/Martin Luther King, and the portion of the conveyance system owned by King County.

WA-002918-1
June 30, 2014

(Ecology Web site)
Permit;
Fact Sheet;
Responsiveness Summary for comments received on Draft Permit  

South Treatment Plant, Renton WAThe South Plant permit covers the operation of the South Treatment Plant in Renton and the portion of the conveyance system owned by King County.

WA-002958-1
Sept. 30, 2009

(Ecology Web site)
Permit;
Fact Sheet;
Appendices

Carnation Treatment Plant, 2009The Carnation Treatment Plant permit covers the operation of the Carnation Treatment Plant and the portion of the conveyance system owned by King County.

WA-003218-2
April 15, 2013

(Ecology Web site)
Permit;
Fact Sheet

Vashon Treatment Plant, Vashon Island, WAThe Vashon Treatment Plant permit covers the operation of the Vashon Treatment Plant and the portion of the conveyance system owned by King County.

WA-002252-7
Aug. 31, 2011

(Ecology Web site)
Permit;
Fact Sheet

Note: Also covered under these permits is the Industrial Pretreatment Program administered by King County. That program is responsible for approving permits for discharges of industrial waste into the sewer system and the management and enforcement of such permits.

* Requires a PDF Reader to view document. If link doesn't work, refer to Ecology's list of permits by NorthWest region at: http://www.ecy.wa.gov/programs/wq/permits/northwest_permits.html

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© 2009 King County



News releases

Other NPDES permits held by King County

Other permited activities include the following:

Other county resources and information

For more information