Project overview
WSDOT will construct a wetland mitigation site inside the Preston Mill Park/Jim Ellis Memorial Regional Park. Project work includes creating and improving wetlands and sensitive area buffers, grading, stream connections, new access roads, plantings, and other improvements. Most work will take place on King County Parks’ property while a small portion will take place on King County roads.
What to expect
Most work will occur inside Preston Mill Park and will cause little, if any, restrictions to travelers. There may be some shoulder work on nearby roads with lane restrictions or flagging. Portions of the park will be temporarily inaccessible to park users during construction.
The State Environmental Policy Act (SEPA) requires the WSDOT to initiate a public notice on all environmental actions. The comment period ended Friday, Feb. 13, 2026.
This project will construct a wetland mitigation site inside Preston Mill Park.
Preston and its surrounding areas in the Snoqualmie Valley have an ancient history. Long before the mill and town were established, this land has been home to the Snoqualmie People, who have hunted, fished and lived in this land to this day.
In the late 19th century, European immigrants built a logging town at Preston, first with a sawmill in Upper Preston that expanded to include a shingle mill at the current Preston Mill Park site.
Today, King County Parks and the Mountains to Sound Greenway Trust have joined forces to create a new park for community gathering and heritage preservation.
WSDOT’s wetland improvements at Preston Mill Park are just a portion of the mitigation efforts related to the nearby SR 18 Issaquah-Hobart Road to Deep Creek widening project.
