Update: The date of the shift to the bypass has changed to Thursday, Jan. 13, weather permitting.
Vehicles will use bypass while crews build new bridge, remove culvert
BLACK DIAMOND – To give salmon a direct path upstream, people who drive on State Route 169 will need to make a slight detour starting Thursday, Jan. 13. That’s when SR 169 will shift onto a temporary 1,000-foot-long bypass between Black Diamond and Maple Valley.
Once vehicles move onto the bypass just west of the existing highway, Washington State Department of Transportation contractor crews from Scarcella Bros., Inc. will begin building a new bridge for SR 169 over Ravensdale Creek. The bridge will replace a narrow culvert that keeps Chinook and coho salmon, steelhead and other fish from continuing upstream.
The crews also will remove one culvert and replace another in the Black Diamond Natural Area, opening an additional 2.4 miles of habitat for resident and migratory fish.
The Scarcella crews built the bypass this fall on the old highway right of way that runs through the Black Diamond Natural Area. The work closed about 1,000 feet of two trails. About 500 feet of trail following the old right of way will remain permanently closed. The remainder will reopen when work is complete in fall 2022.
The bypass will allow people in the 12,000 vehicles that use the highway each day to continue their travels with minimal disruption. When work is complete, the bypass will be removed and restored to a natural state.
Improving fish passage
This project will correct three culverts that currently block fish passage. Water travels through these culverts too fast for fish to continue upstream. In addition to the bridge for SR 169, the crews will build a new bridge for the trail that follows the railroad grade and restore a natural bed for Ravensdale Creek. They will remove the culvert under the old highway right of way and rebuild that creek bed as well.
Most of the funding for this $11.4 million project comes from the Connecting Washington funding package approved by the state Legislature in 2015.