I-5 - Fisher Creek - Fish Passage

Project news

  • Crews have completed work and are now monitoring plant establishment.
  • All lanes are back open and speed limits are back to normal on I-5.


Why is WSDOT building bridges for I-5 over Fisher Creek?
Fisher Creek, located about five miles south of Mount Vernon in Skagit County, passes under I-5 in an 8-foot diameter culvert. The culvert is rusting out and some of the soil west of the southbound paved shoulder is washing away. It also creates a barrier to fish passage because the water moves too fast for fish at high water times, and is 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 will allow for better fish passage.

Why not 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 are the challenges to building bridges for I-5 over Fisher Creek?

  • Keeping traffic moving: I-5 remains open in both directions during construction work. WSDOT contractor crews started the project by building two bypass lanes in the I-5 median. Southbound traffic used these lanes during construction of the southbound bridge and then northbound traffic during construction of the northbound bridge. Both directions are now back in the normal lanes. 
  • Narrowing the interstate from three to two lanes: At Fisher Creek, I-5 has three lanes in each direction that are separated by a wide median. Traffic has been narrowed to two lanes while the bypass is the median is removed and the speed limit is reduced from 70 to 60 mph approaching the work zone. Two lanes are sufficient for the 59,000 average daily trips that use this section of I-5.
  • Working near wetlands: Contractor crews will need to be careful working near and above the creek to keep any construction material and sediment out of the creek and wetlands.

What should drivers expect?

  • Lane reductions: Drivers should be prepared for lane reductions to start well before the construction zones. I-5 will narrow from three lanes to two, then expand back to three once motorists pass the work zone.
  • Reduced speeds: During construction, the speed limit through the work zone is reduced from 70 to 60 mph.

How will the work be 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 are now removing the bypass lanes, the remaining fill and existing culvert, and building a more natural creek bed for Fisher Creek. They’ll also plant the new creek banks with native vegetation.

The End Result
Building two bridges to replace the Fisher Creek culvert will help restore the creek to a natural state, open up more than 17 miles of fish habitat for salmon and steelhead, and comply with the U.S. District Court ruling.

Project Benefits

  • This project will improve fish passage and open up additional salmon and steelhead habitat.
  • The work will help WSDOT comply with the U.S. District Court ruling regarding fish passage.

What is the project timeline?

  • Winter 2016: Advertise project for competitive bidding.
  • Spring 2016: Begin construction of the bypass lanes in I-5 median.
  • Summer 2016: Temporarily diverted southbound I-5 to bypass lanes.
  • Late fall 2016: Returned traffic to southbound I-5 regular lanes.
  • Winter/spring 2017: Temporarily diverted northbound I-5 to bypass lanes
  • Summer 2017: Returned traffic to northbound I-5 regular lanes.
  • Summer-fall 2017: Remove bypass lanes, restore Fisher Creek bed.

Financial Information

Financial Data for PIN 100560D
Funding Source Amount ($ in thousands)
2003 Gas Tax (Nickel Funding) $0
2005 Gas Tax (TPA) $0
Pre-Existing Funds (PEF) $1,135
CWA $7,650
Total $8,785


How can I get more information?

Andrea Petrich
WSDOT communications
Phone: 360-757-5963
Email: petrica@wsdot.wa.gov

Shane Spahr
WSDOT Project Engineer
Phone: 360-848-7103
Email: spahrs@wsdot.wa.gov