Continuous right lane closures on northbound and southbound SR 161 near South 370th Street in Federal Way began Monday, July 28, for fish barrier removal on a tributary to Hylebos Creek that runs beneath SR 161. These closures will remain in place for roughly 60 days.
Continuous single-lane closures on South 370th Street at the intersection of SR 161 began Aug. 4 for utility work and will last for about six weeks.
In September, all lanes on SR 161 will close for three days (Fri. night through Mon. morning) to replace the culvert with a much larger structure. We'll share details on the closure when the work is scheduled.
Project overview
Three culverts that block fish passage on tributaries to Hylebos Creek beneath SR 161 in Milton and Federal Way will be replaced with new structures that restore natural stream conditions. Crews also will make habitat improvements within the streams where they pass beneath the state highway. Construction is scheduled to begin in Summer 2025 and continue into fall/winter 2025.
What to expect
Construction will begin along SR 161 in Federal Way and Milton as early as June 2025 for the removal of fish barriers on three tributaries to Hylebos Creek.
People should plan for the following during construction in 2025:
- Continuous right lane closures on both directions of SR 161 near South 370th Street in Federal Way starting Monday, July 28.
- A weekend-long closure on SR 161 between South 370th Street and 28th Avenue South. This work is tentatively planned for September 2025 after Labor Day Weekend.
- Signed detours on local streets to guide vehicles, cyclists and pedestrians around the work zone.
- Additional traffic and congestion along detour routes during peak traffic times.
- Temporary changes to King Country Metro bus routes.
Upgrading two culverts on SR 161 between 28th Avenue South and Military Road South will require an extended full closure on all lanes of SR 161 lasting roughly 9 days. This work is tentatively planned for Summer 2026. We will provide additional details on construction when the work is scheduled.
A map showing the locations of three culverts that will be replaced under SR 161 to Hylebos Creek near Federal Way and Milton.
