NW Sammamish Road fully closed at 7 a.m. on Monday, October 5, and the City of Issaquah said the closure would last about six weeks. Through traffic is being sent around on West Lake Sammamish Parkway Southeast and I-90, and homes inside the closed stretch keep local access. This closure is the first in a sequence that runs through 2027. Partway through that sequence, the Parkway carrying today's detour traffic gets a full closure of its own.
All of it comes from one WSDOT contract, the I-90 Lewis, West Village Park and Schneider Creeks fish passage project. Each closure is set by where one of three small creeks crosses under a road.
The sequence, in WSDOT's own order
The current closure is for utility work. Before crews can dig, power and other services have to be moved out of the way. WSDOT places the closure just west of Lake Sammamish State Park and lists the road as closed until mid-November. Utility companies said they would contact nearby residents directly about any service interruptions.
WSDOT's milestone table lays out the rest:
| When | What happens |
|---|---|
| February 2026 | Westbound I-90 traffic moves onto bypass lanes |
| October to mid-November 2026 | NW Sammamish Road closed for utility relocation |
| January 2027 | NW Sammamish Road construction begins, full closure |
| Spring 2027 | NW Sammamish Road work done; eastbound I-90 shifts to its own bypass |
| Summer 2027 | West Lake Sammamish Parkway work begins, full closure |
| Fall 2027 | Eastbound I-90 and West Lake Sammamish Parkway work complete |
| By December 2029 | Work at all locations complete |
The City of Issaquah expects the January closure to last about four months, with the same detour routes and the same local access as this fall. If WSDOT stays on schedule, NW Sammamish Road reopens in spring and West Lake Sammamish Parkway closes in summer. For this year and next, that pushes the main routes around the north end of Lake Sammamish State Park off the map one after another.
The I-90 work runs alongside all of this. WSDOT tells drivers to expect westbound traffic shifts near the 17th Avenue Northwest and Lakemont Boulevard interchanges, overnight lane reductions, and detours around closed on-ramps, off-ramps and surface streets. The project page does not list dates for those ramp closures, so they will come as separate notices.
Three creeks, three reasons for the cones
Each road closure lines up with a specific creek, and WSDOT rates each creek's I-90 crossing a barrier to fish.
- Lewis Creek runs under I-90 near Lakemont Boulevard. WSDOT calls its culverts "completely impassable." The creek is home to Chinook, coho, resident trout, steelhead, sockeye and sea-run cutthroat. A new crossing could open more than 2.5 miles of habitat, the most of the three.
- West Village Park Creek crosses under I-90 just east of Southeast 51st Street. Its culvert is also rated completely impassable. Replacing it could open more than half a mile of habitat for coho, resident trout, steelhead and sea-run cutthroat.
- Schneider Creek sits at the west edge of Lake Sammamish State Park. WSDOT rates it only 33 percent passable. A larger structure could add nearly three-quarters of a mile of habitat for coho, resident trout, steelhead, sockeye and sea-run cutthroat.
Schneider Creek is the one behind the January closure. It runs under I-90 and also under NW Sammamish Road. In early 2027, crews will pull out the old culvert under NW Sammamish Road and build a bridge and a new creek bed in its place. According to WSDOT's project map, the structures near Lake Sammamish will carry both West Village Park and Schneider creeks, and the Lewis Creek work is the piece out by Lakemont. WSDOT says it will build new I-90 bridges at both Lewis and Schneider creeks. Clark Construction describes the whole job as seven new bridges and 4,500 linear feet of stream restoration.
Why a $204 million job is happening here
WSDOT estimates the combined cost at $204 million. The construction contract was awarded on October 14, 2024 to Guy F. Atkinson Construction for $157,590,985. For three creeks that most drivers on I-90 never notice, that is a lot of money. The reason is a court order.
In the federal culvert case, 21 northwest Washington tribes asked the court to rule that the state has a treaty-based duty to preserve fish runs. The permanent injunction issued in March 2013 requires the state to speed up removal of state-owned culverts that block salmon and steelhead habitat. According to WSDOT's injunction page, the agency had corrected 200 injunction-barrier culverts as of June 2026, reopening 705 miles of habitat. WSDOT also says more funding is needed to reach the goal of opening 90 percent of potential habitat. The Issaquah crossings are one local share of that statewide count.
For drivers, the end date is still a moving target. WSDOT schedules completion for December 2029. The contractor's project page lists 2028. As the owner of the project, WSDOT is the date to plan around.
What the closure means for the state park this fall
The NW Sammamish Road closure sits right at the park's doorstep. Lake Sammamish State Park's address is 2182 NW Sammamish Road. In a notice posted October 2, Washington State Parks says the park will stay open through the closure but warns of heavier traffic getting in from early October to late November. That notice runs through November 30. The city's six-week estimate ends earlier, so allow a little extra time on park trips until December.
Two closures inside the park have nothing to do with WSDOT. The footbridges over Issaquah Creek and Tibbetts Creek have been closed since State Parks' March 3 notice. Winter high water eroded them, and State Parks has not given a date for the repairs to be finished. Parking still needs a Discover Pass, which costs $10 for a day or $45 for a year.
The park's fall calendar fits around the closure:
- Lakeside Lectures: Kokanee, Wednesday, November 4, 5:30 to 7 p.m. UW professor Jeff Jensen and Dave Kyle of Trout Unlimited will talk about the kokanee salmon that Friends of Lake Sammamish State Park describes as endemic to the lake. Registration is through Friends of Lake Sammamish State Park. The lecture falls inside the current closure window, so plan on taking the detour.
- Lake Sammamish Holiday Market, Saturday, December 5, 10 a.m. to 2 p.m., at 2010 NW Sammamish Road. This is the first year for the market. Friends of Lake Sammamish State Park and the Mountains to Sound Greenway Trust are hosting it alongside their Adopt-a-Living-Tree program.
The lecture also comes at a good time of year. The Washington Department of Fish and Wildlife says Lake Sammamish kokanee usually start leaving the lake to spawn in its tributaries in late October and early November. WSDOT identifies Lewis Creek and West Village Park Creek as tributaries of Lake Sammamish, and both are among the creeks this road project is opening up for salmon and trout.
The salmon run itself is easier to see in town. Visit Issaquah logged the first salmon in Issaquah Creek on August 27 and says the run lasts from late August through November. The Issaquah Salmon Hatchery at 125 W. Sunset Way is free and open every day from dawn to dusk. Its viewing bridge and fish ladder are open all day, and the visitor rooms and restrooms are open 8:30 a.m. to 4 p.m. Getting downtown from the Lakemont side means using the I-90 interchanges where WSDOT has warned of westbound traffic shifts.
Tibbetts Creek runs on a separate clock
Tibbetts Creek, the creek behind the closed park footbridge, also has a highway crossing on WSDOT's list. It started out as part of this contract. WSDOT later moved the SR 900 work into a separate project, which it says is likely to go out for bids in late 2026. On the SR 900 Tibbetts Creek project page, the crossing is at milepost 19.5, north of Squak Mountain State Park. A new structure there could open 1,763 meters of habitat. WSDOT estimates the cost at $10 million. Work could begin as early as 2027, but the fish passage program still needs funding from the Legislature, and WSDOT says construction timing is unknown. Closures on SR 900 will depend on how the contractor designs and builds it, so WSDOT has no detour plan yet.
That leaves a short list of dates to keep. NW Sammamish Road should reopen around mid-November, with State Parks' congestion notice running through November 30. The four-month Schneider Creek closure starts in January 2027. West Lake Sammamish Parkway closes in summer 2027. WSDOT's email updates are where the exact dates will show up first. Questions about the closures can go to WSDOT Communications at 206-440-4696.
If you're planning a move or a sale on Issaquah's west side and want to see how the 2027 closures line up with your dates, Andrew M. Wenzl can go over the calendar with you and give you a straight answer. You can find more on the area on the Issaquah neighborhood page. Let's Connect.
