Vashon Wastewater Treatment Plant

Construction is complete on the new wastewater treatment plant that’s now protecting public health, water quality and local beaches for Vashon Island residents. The plant treats sewage from the Vashon Sewer District, which serves about 425 residential and commercial customers in and around the island’s main business area. The new plant is able to handle Vashon’s present and future wastewater treatment needs. It also has safe and reliable back up systems.

Positive Benefits for the Puget Sound

As part of the project, the treatment plant outfall pipe was extended an extra 1,450 feet into the Puget Sound. The pipe now discharges 2,800 feet offshore and out of the range of geoduck beds in the area.

Mitigation for the outfall project included the removal of 5.3 acres of derelict gill nets in Colvos Passage and Shilshole Bay. Abandoned, lost and discarded fishing gear can cause safety problems in marine waters for divers and sea life.

Collection and Treatment Process Overview

This graphic is also available as a PDF file (390 KB).

For more information

• Contact Jo Sullivan about King County's project at 206-296-8361 or jo.sullivan@kingcounty.gov.
• Spring 2007 Project Update (1.3 MB, PDF)
• Past news releases, plant upgrade project and Vashon Treatment Plant home page.

Department of Natural Resources and Parks
Wastewater Treatment Division
201 S. Jackson St.
Seattle, WA 98104-3855
Fax: 206-684-1278

Updated: April 15, 2008

Related Information:

WTD Facts at a Glance