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Why did WSDOT build bridges on I-5 over Fisher Creek?
Fisher Creek, located about five miles south of Mount Vernon in Skagit County, passes under I-5 and used to run through an 8-foot diameter culvert. The culvert was rusting out and some of the soil west of the southbound paved shoulder was washing away. It also created a barrier to fish passage because the water moved too fast for fish at high water times, and was too shallow during low water times. In 2013, the U.S. District Court for Western Washington ruled that the state must remove culverts that block fish passage under state roads. Fisher Creek is one of more than 1,000 in this state subject to this ruling. Removing the culvert, building twin 110-foot-long bridges and reconstructing the creek bed to a more natural state allows for better fish passage.
Why didn't WSDOT just put in a new culvert?
The normal width of the creek at peak flow is about 30 feet, which is too wide to fit into a standard culvert.
What were the challenges to building bridges for I-5 over Fisher Creek?
What did drivers experience?
How was the work performed?
While southbound traffic was diverted on to the bypass lanes, crews removed a section of all three southbound lanes and shoulders of I-5, removed some of the underlying fill, and built a new bridge. Traffic was then returned to the regular lanes. Crews then diverted northbound traffic onto the two median bypass lanes and followed the same steps to build the northbound bridge. Crews then removed the bypass lanes, remaining fill and existing culvert, and built a more natural creek bed for Fisher Creek. They also planted the new creek banks with native vegetation.
The End Result
Building two bridges to replace the Fisher Creek culvert has restored the creek to a natural state, opened up more than 17 miles of fish habitat for salmon and steelhead and complied with the U.S. District Court ruling.
Project Benefits
What is the project timeline?
Financial Data for PIN 100560D
Funding Source Amount ($ in thousands)
Northwest Region Communictions
nwpublicaffairs@wsdot.wa.gov
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