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For questions about the Wastewater Treatment Division Web site, please send an e-mail message or contact us at:

King Street Center
201 S. Jackson St., Suite 505
Seattle, WA 98104-3855
Phone: 206-684-1280
Fax: 206-684-1741
Telecommunication device for the deaf (TTY): 711

Get Directions to our office location in Seattle, Washington.

Staff Contacts

Puget Sound shoreline next to the West Point Treatment Plant, Seattle

South Treatment Plant

History

  • No Swim KidsIn 1958, King County voters created Metro, an agency charged with developing and operating a regional wastewater treatment system.
  • The South Plant, a secondary treatment plant, was completed in 1965.
  • In 1986, a new effluent discharge pipeline and outfall was completed to eliminate discharges to the Green/Duwamish River and carry treated wastewater 12 miles to a deep-water outfall in Puget Sound.
  • In 1994, resulting from a voter approved proposal to merge Metro with King County, King County assumes responsibility for South Plant.
  • In 1997, South Plant began producing reclaimed water.
  • In 2001, the South Plant was expanded to its current capacity of 115 mgd (million gallons per day) of average wet weather flow and 325 mgd during peak storms.
  • South Plant celebrated its 40 year anniversary on Saturday, October 8, 2005. View Summer 2005 South Plant Newsletter (PDF).

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