Island Center Forest

Island Center Forest Health Work – Bypass Thin (Update May 2026)

King County Parks is planning 45.4 acres of commercial tree thinning in Island Center Forest across eight units, and 4.7 acres of drop-and-leave cutting in four alder “gap” cuts. Along Fir Hill Trail, dead and dying trees that pose a risk to trail users will be cut and left on-site. View a map of the project site. The project’s objectives are to reduce the Douglas-fir forest’s density to improve long-term drought and climate resilience, allow space for planting root rot-resistant tree species, and initiate a new cohort of trees in areas with declining red alder tree canopy and carbon volumes.

A few permitting steps remain before this work can begin:

1) In summer of 2026, King County plans to file a SEPA Checklist Addendum to supplement the original SEPA checklist from 2024 that incorporates changes based on comments from the original SEPA. 

Here’s a summary of comments we’ve heard from the public, and the County’s responses. [Insert link to Comment Response Summary]

The King County Parks Public Notices page has all SEPA documents issued to date.  Once the SEPA Addendum and Notice of Action Taken are files, they will also appear here. Scroll down for “Island Center Forest Bypass Thin”https://kingcounty.gov/en/dept/dnrp/nature-recreation/parks-recreation/king-county-parks/parks/public-notices

2) The County plans to concurrently file a Notice of Action Taken, which is an optional final step in the SEPA process. People or organizations may file an appeal during the 21-day open period of the Notice of Action Taken. To start the Notice of Action period, the County is required to notify neighbors and people or organizations that have provided comments on this project. 

3) The County will also apply for a Forest Practices Permit from Washington DNR in summer 2026.

4) The County will obtain a County Right of Way Use Permit, if needed, before work begins. 

Project Details: 

• Most of the work (36 acres) will take place in dense Douglas-fir areas, cutting and removing about half of the Douglas-fir trees. The objectives for the Douglas-fir treatments are to shift from overly-dense stands to less-dense, more diverse and drought-resistant conifer stands; prevent density-dependent tree mortality; slow the spread of laminated root rot and plant with rot-resistant species.
• In the red alder stands (9 acres), treatments will transition the forest from declining alders to more diverse, climate resilient mixed species stands. Most alders will be cut and removed, while all other trees will be retained. Alders make up around 2/3 of the tree species in the red alder stands (Douglas-fir and other conifers make up the other portion). The County will replant the stand with conifers and will also encourage naturally-resprouting red alder to re-initiate a new cycle of this short-lived species.
• This project is part of King County’s commitment to sustainable long-term timber production in line with ICF’s “working forest” designation, described in King County’s Comprehensive Plan (2022). Similar projects have taken place at ICF since 2008.
• 115th Ave SW will remain open to residents at all times during the work (both on the north end of the park coming from SW Bank Rd, and the south end coming from SW Cemetery Rd). The roads will be maintained for passenger vehicles at all times during the work. The gravel portion of 115th Ave SW on the north end coming from SW Bank Rd will undergo long-overdue maintenance to return that road to County road standards.
• Several trails, Mukai Trailhead, and Cemetery Trailhead will be closed for an estimated 8 weeks while the work takes place. Trail closures will include portions or all of Techmo, 115th Bypass, 188th Bypass, Landtrust, Gallops, Fir Hill, Valley of the Firs, and others for some or all of the project duration. King County will minimize trail impacts and closures as much as possible. 115th Bypass Trail will undergo substantial grading, drainage improvements, and cutting back vegetation along the shoulders. 188th Bypass between 115th Bypass and Fir Hill Trails with be obliterated and revegetated after the project upon request of King County Backcountry Trails. The new 188th trail will be the east-west route connecting those trails.

For additional information, please contact King County Parks Forester Paul Fischer, 206-817-8259 (cell) or pfischer@kingcounty.gov.

About the Park

Located in the center of Vashon Island, Island Center Forest is a Forest Stewardship Council® (license code FSC-C008225) certified working forest and natural area managed to demonstrate sustainable forest management while protecting and restoring the health of the site's habitat. Enjoy a picnic at the Forest Cathedral picnic shelter designed and built by islanders using local island wood.

Ten miles of multi-use trails lead visitors through 440 acres of consisting of forested stands, meadows, the Mukai Pond and the Meadowlake wetlands which form the headwaters of Judd Creek. Island Center Forest is habitat to a variety of wildlife, including more than 70 bird species.

Coinciding with the Washington Department of Fish and Wildlife’s designated hunting season in October, 220 acres of Island Center Forest are open for seasonal deer hunting and closed to other visitors, making this the only public land on Vashon Island where deer hunting has been allowed.

Park activities and facilities