Island Center Forest

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

Island Center Forest Bypass Thin likely will start in August 2027. King County Parks had planned to start work on the Island Center Forest Bypass Thin forestry project in September 2026, but delays in permitting and the seasonally limited dry-weather work window has pushed this project to 2027. Parks Forestry Program observes a no-work period to protect bird nesting season from April 15 to July 31, so the soonest in-forest work would start is August 2027. Contractor availability and weather conditions will determine the actual start date.

One task is ready for work: creating canopy openings in an alder forest, located southeast of Mukai Pond. The County plans to cut those openings (units 10 through 13 the map) by the end of 2026 and plant them with mixed native conifers in the early months of 2027. Short trail closures will be required along the Meadowlake Trail for 1 or 2 days. The County will post closure notices once the work is scheduled.

Road maintenance work may begin in the summer of 2027 before the in-forest work, starting along 115th Ave SW from SW Bank Rd into the Mukai Trailhead.

The County will update this website and send e-newsletter updates as the permitting and contracting steps progress this fall and winter.

Project summary

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.

Permits and next steps

King County has obtained an approved Washington Department of Natural Resources Forest Practices Application permit, number SP-FPA-26-9038. The County also issued a SEPA Environmental Checklist Addendum and a Notice of Action Taken that concluded in August 2026, completing the State’s SEPA process. The County awaits a Right of Way Use Permit for our maintenance work along the gravel portion of 115th Ave SW from SW Bank Rd to the Mukai Trailhead.

Here is a summary of comments we’ve heard from the public, and the County’s responses. There is also a SEPA Environmental Checklist Addendum. 

The King County Parks Public Notices page has all SEPA documents issued to date and additional background documents.

Once the final permit is obtained, the County will circulate an Invitation to Bid for the work and select a contractor for the work.

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