Maury Island Open Space

Facility Site ID: 2901216 Cleanup Site ID: 1532

Site Status - November 2019

In April 2018 Ecology hosted a public comment period and meeting for a cleanup plan and associated documents related to the Maury Island Open Space Site.  The plan specifies environmental standards, cleanup methods, and scheduling as part of an existing agreement between Ecology and King County. The following documents were available for public comment:

  • Remedial Investigation: details an investigation of the nature and extent of contamination at the Site.
  • Feasibility Study: identifies 5 alternatives, and a preferred alternative, for addressing contamination at the Site.
  • Draft Cleanup Action Plan: describes how the preferred alternative will be implemented at the Site.
  • State Environmental Policy Act-Determination of Non-Significance: a determination that the cleanup work is not likely to harm the environment.

Ecology received 34 comments on these documents, and responded to all of them in a Response To Comments document. No comments warranted any changes to the draft documents, so Ecology made them final and authorized King County to proceed with the Cleanup Action Plan, which it has been doing since that time.

Stay tuned to this page for updates, and find additional information about the Maury Island Open Space park on King County's webpage.

Site Description

Maury Island Open Space cleanup area. Cleanup area is outlined in yellow. Click on the map to enlarge it.
Maury Island Open Space cleanup area. Cleanup area is outlined in yellow. Click on the map to enlarge it.
The site is approximately 266-acres in size and is located on the southeast side of Maury Island situated on a sea bluff above Puget Sound. A portion of this property was formally operated as a sand and gravel mine by CalPortland (previously known as Glacier NW). The County acquired this property in 2010 and it is currently open to the public for non-motorized recreation, including walking, jogging, hiking, mountain biking, and equestrian use.

The site contains Madrone forests and has adjacent marine habitat that supports endangered species such as chinook salmon, orca and bull trout. The site’s nearly one mile of shoreline is the longest undeveloped stretch of shore in King County. When combined with the County’s nearby 320 acre Maury Island Marine Park, the two properties represent the largest public holding of protected marine shoreline in all of Puget Sound.

Environmental investigations at the site have shown that contaminants exist throughout the site as a result of fallout from the former ASARCO Tacoma Smelter smokestack, and from former skeet shooting activities in the area.  Contaminants include arsenic, lead, and polycyclic aromatic hydrocarbons (PAHs) in the soil.  Concentrations exceed levels allowed under the state’s cleanup law, the Model Toxics Control Act (MTCA) and must be addressed.

For almost 100 years the Asarco company operated a copper smelter in Tacoma. Air pollution from the smelter settled on parts of King, Pierce, Kitsap, and Thurston counties, creating the Tacoma Smelter Plume. High concentrations of arsenic and lead from the smelter operations have been found in surface soils of Vashon - Maury Island, with properties closer to the former smelter having higher contamination. This site is within the Tacoma Smelter Plume but is being cleaned up on a separate track through the formal cleanup program, under the management of the Northwest Regional Office of the Toxics Cleanup Program. Ecology’s Southwest Regional Office is managing the overall Tacoma Smelter Plume cleanup. Ecology funds and manages the Soil Safety Program as part of cleaning up the Tacoma Smelter Plume.
Legal 1
Document Title Document Date Document Type
Maury Island Open Space Agreed Order for RI, FS and draft CAP 2013 2/4/2013 Agreed Order
Public Information 5
State Environmental Policy Act 1
Document Title Document Date Document Type
SEPA Determination of Non-Significance and Checklist 3/1/2018 SEPA Documents
Technical Reports 10
Document Title Document Date Document Type
Maury Island Open Space Property Engineering Design Report 7/27/2020 Engineering Design Report
Maury Island Open Space - Final Cleanup Action Plan - November 2019 11/28/2019 Cleanup Action Plan
MINA Compliance Monitoring Plan 6/20/2019 Site Specific Technical Document - other
Maury Island - Remedial Investigation - March 2018 3/1/2018 Remedial Investigation Report
Maury Island - Feasibility Study - March 2018 3/1/2018 Feasibility Study
Maury Island Open Space - Interim Action Workplan - June 2016 6/30/2016 Interim Action Documents
Maury Island Open Space - Final Remedial Investigation 6/2/2014 Remedial Investigation Report
Maury Island Open Space Draft Final Skeet Range Investigation Report 6/27/2011 Remedial Investigation Report
Maury Island Open Space RI/FS Work Plan 2010 11/5/2010 Remedial Investigation Work Plan
Maury Island Gravel Mine Impact Study - Nearshore Impact Assessment 3/1/2000 Remedial Investigation Report
There may be more documents related to this site. To obtain documents not available electronically, you will need to make a public records request.

Places to see print documents

  • Northwest Regional Office
    15700 Dayton Ave N
    Shoreline, 98133
    Please schedule an appointment to view print documents at this location.
  • Vashon Library
    17210 Vashon Highway SW
    Vashon Island, 98070
    This location may only have print documents available during open comment periods.

Contaminants 2

Contaminant Type
Surface Water
Metals - Metals Priority Pollutants C
Metals - Arsenic C
Confirmed Above Cleanup Levels
Below Cleanup Levels
This contaminant list was based on our best information at the time it was entered. It may not reflect current conditions at the site.