Maury Island Open Space

Last Updated: June 2024

Información en español

Fact sheet  |  Postcard (February 2024)

Response to Comments (June 2024)

Ecology held a 30-day comment period (February 26 - March 26, 2024) to review an amendment to the legal agreement (Agreed Order) with King County that addresses contamination at the Maury Island Open Space cleanup site (site). The site is now referred to as the Maury Island Natural Area by King County.

As of December 2023, King County has already completed the first two cleanup phases of the Cleanup Action Plan. (See below)

The procedural amendments to the legal agreement included:

• The final 2019 Cleanup Action Plan and an updated schedule of deliverables to complete the remaining phases.
• An Environmental Covenant to restrict land uses on the site such as maintaining the capped roads and trails and not disturbing contaminated soil without Ecology permission.
• Updated legal language to comply with updated applicable laws.

Ecology has reviewed and considered the public comments received on the legal agreement amendment. Based on Ecology’s evaluation of the comments, no changes to the document were necessary, and it is being finalized.

King County will continue completing Ecology’s Cleanup Action Plan through 2029:

• Revegetate several areas within the site.
• Cap maintenance roads and majority of trails with a minimum of 3 to 4 inches of compacted gravel and a 3-inch-thick layer of mineral soil or additional gravel.
• Decommission some trails and redundant trail spurs.
• Complete limited wetland remediation near gravel parking lot. 

The Model Toxics Control Act (MTCA) is Washington’s environmental cleanup law. It provides requirements for contaminated site cleanup and sets standards that protect human health and the environment. Ecology enacts the MTCA and oversees cleanups.

The MTCA site cleanup process is completed in steps (see graphic) over a variable timeline.

Completed cleanup phases:

• Phase 1: 1A in July 2019: Capped all trails; 1B in October 2020: Cleaned up skeet range and removed invasive vegetation in Acres 4-6

• Phase 2:  March 2022: Planted Acres 4-6

Future cleanup phases with schedule details in legal agreement amendment:

• Phase 3:December 2024: Cleared and planted Acres 7-10

• Phase 4: December 2026: Clear and plant Acres 11-13 and complete wetland remediation

• Phase 5: December 2029:  Clear and plant Acres 14-16

Current Maury Island Open Space cleanup site Public Participation Plan (Updated February 2024)

This plan includes information for the public regarding opportunities to get involved in the Site cleanup process. The outreach activities and mechanisms presented reflect Ecology’s current plans for keeping the public informed and for receiving information and comments from the public. 

Ecology’s Cleanup Action Plan requires King County to: 

• Revegetate several areas within the site.
• Cap maintenance roads and majority of trails with a minimum of 3 to 4 inches of compacted gravel and a 3-inch-thick layer of mineral soil (or equivalent).
• Decommission some trails and redundant trail spurs.
• Complete limited wetland remediation near gravel parking lot.

The site is approximately 266-acres and is located on the southeast side of Maury Island above Puget Sound. A portion of the site was formally operated as a sand and gravel mine by CalPortland (previously known as Glacier NW), and the 1-mile shoreline is the longest undeveloped stretch of Puget Sound shoreline in King County. The County acquired the site in 2010. It is currently open to the public for non-motorized recreation, including walking, hiking, mountain biking, and equestrian use. 

Environmental investigations have shown that contaminants exist throughout the site because of fallout from the former ASARCO Tacoma Smelter smokestack, and from former shooting sports activities in the area. These include arsenic, lead, and polycyclic aromatic hydrocarbons (PAHs) in the soil that exceed levels allowed under the state’s cleanup law, the Model Toxics Control Act (MTCA).

This site is within the Tacoma Smelter Plume. Ecology’s Southwest Regional Office manages the overall Tacoma Smelter Plume cleanup. This site is being cleaned up on a separate track through the formal cleanup process, under the management of the Ecology’s Northwest Regional Office. Ecology funds and manages the Soil Safety Program as part of cleaning up the Tacoma Smelter Plume.

En español 

Si le gustaría recibir documentos en español, por favor llame a 425-324-5901 y espere a que un intérprete se una a la llamada o envíe un correo electrónico a preguntas@ecy.wa.gov.

Traducciones de avisos públicos para Maury Island Open Space se preparan bajo solicitud.