Responding to Washington State Department of Transport’s plan to replace a bridge damaged by changes in river level, the National Park Service intends to construct engineered logjams.

The logjams in Olympic National Park are intended to improve river channel dynamics and provide habitats for salmon. They will create pools and stable alluvial islands on which trees can grow to improve shading of the water. The logjam project is open for comment until 22 November (link opens in new tab).

Elwa River Bridge, built in 1926, carries the US 101 and is 8.5m wide. The new bridge is 12m wide to accommodate cyclists and pedestrians. Construction began in April, and will be complete in winter 2024.

Elwha bridge piers were discovered to be built on gravel, not bedrock. Erosion has significantly damaged the piers after the river changed course and flow over the years. Credit: WSDOT

The bridge is being replaced because the riverbed has lowered and the bridge’s foundations have become eroded. Remedial work was done in 2016, and the bridge has been monitored ever since with tilt and crack meters and an enhanced inspection routine.