US 97 - Blewett Pass Culverts Replacement

Project news

US 97 Blewett Pass reopened to all traffic at 9 a.m. Friday, Sept. 14, following culvert replacement work. 

What we did during the closure: 
While the pass was closed, Washington State Department of Transportation contractors replaced three culverts under the highway.

Two box culverts were installed north of the top of the pass, one, the tributary to Tronsen Creek, is 1½ miles from the summit and the other, at 5 Mile Creek, is 4½ miles from the top of the pass. A third culvert was replaced at Swauk Creek, five miles south of the Blewett Pass summit.

Two of the culverts are undersized and became plugged with debris during storms, leading to roadway washouts. The size and orientation of the culvert on Swauk Creek has been a barrier for spawning trout and salmon.

The entire work on these projects will be complete by the end of September and the remaining finish work will require some occasional single-lane closures when needed. Expect any delays will be less than 20 minutes.

Needs & Benefits

The old culvert on Swauk Creek was a barrier to salmon and resident trout due to its size and orientation. The culverts on the north side of Blewett Pass needed to be replaced because they were undersized and had a history of plugging with debris during storms, leading to washouts along the highway.


Contract #9236 for the north summit culverts was awarded to Pipkin Construction of Wenatchee on April 17, 2018, for $1.1 million. Contract #9274 for the south summit culvert was awarded to Hurst Construction of East Wenatchee on May 29, 2018, for $1.2 million.  Both projects will take 20 working days to complete (four weeks).


Two culvert replacements are Capital Preservation Drainage projects to increase capacity and the third is a Capital Improvement Environmental Retrofit project to remove a fish barrier. The combined state and federal funding for the construction is $2.3 million.


Dan Lewis, Project Engineer 509-667-2880

US 97 - Blewett Pass Culverts - thumbnail map

These are the three culverts that were removed and replaced, requiring closing the road entirely for a week.

damage happens when the culvert can't handle the runoff

What happened when culverts failed