Project overview
In 2021 and 2022, between Maple Valley and Black Diamond we replaced the culvert that carries Ravensdale Creek under SR 169, along with two other nearby culverts. The existing culverts were narrow, which forces the water through too quickly for salmon and other fish to continue upstream.
What to expect
In January 2022 we shifted traffic onto a two-way bypass just west of the current SR 169 roadway. This allowed us to keep people moving along the corridor north of Black Diamond during construction. The new bridge opened to traffic in mid-July 2022 and the pedestrian bridge downstream opened to the public in fall 2022.
Construction affected a few trails in the Ravensdale Creek Natural Area as well. We temporarily closed about a quarter-mile of trails and permanently closed one-tenth of a mile of trail, which is about 0.5 percent of the entire system.
While construction on the road was finished by fall 2022, there was a lot of plant establishment work left to do in late 2022 and early 2023 in the project area. Crews wrapped up punch list items by early fall 2023.
We are working with King County Parks on this project to replace three old culverts in the Black Diamond Natural Area. This will open an additional 2.4 miles of habitat for salmon, steelhead and other fish.
The existing 6-foot by 5-foot culvert is 82 feet long beneath SR 169. During spawning season water travels too quickly through this culvert to continue upstream. We've replace this culvert with a bridge, opening up the creek and surrounding wetlands. There are two other culverts nearby that also would limit fish passage, so in conjunction with King County Parks we are fixing those as well. We'll remove one culvert, located about 200 feet downstream. At the third culvert, about 350 feet downstream, we'll remove it and build a bridge for the hiking trail in the area. All of this will open up an additional 2.4 miles of habitat for Chinook and coho salmon, steelhead and other species.
