A section of Mount Baker Highway west of Glacier will be reduced to one bypass lane as crews build a bridge, the state Department of Transportation said.
Construction of the bridge over Hedrick Creek, about a mile west of Glacier, will reduce traffic to one lane around the clock, and temporary stoplights will guide traffic through the bypass lane next to the original route.
The speed limit there will be reduced to 25 mph.
The new bridge will replace an old, narrow culvert with a larger space for Chinook and Steelhead salmon to pass through under the road, the department said, and to restore historical migration patterns.
It will give 3,000 more feet of habitat to migratory fish. The project is part of a larger effort to improve fish passages and reconnect streams.
The larger passage is also intended to increase driver safety by allowing other animals a larger space to pass under the road instead of over it.
The bridge is expected to open to traffic in October, and the project should be complete about a year later. The work is expected to cost about $7 million, the department said. Bellingham-based Strider Construction is doing the work.