Description:
The Hwy 101 box culvert at river mile 2.4 is a serious, partial barrier to 1) upstream fish passage and 2) the downstream transport of large wood. Fish passage and large wood transport will be restored by removing the culvert and replacing it with full-spanning bridge.
Why is the project needed:
Siebert Creek's anadromous length is approximately 10 miles, but fish passage is severely impaired at river mile 2.4 by the Hwy 101 box culvert. The culvert is equipped with a sub-standard fishway that provides, at best, partial fish passage. The culvert is too small to accommodate an efficient fishway, and the large amount of bedload transported by Siebert Creek makes fishway maintenance very problematic. The project will remove the box culvert and replace it with a bridge to restore unimpeded fish passage to prime spawning and rearing habitat upstream for Puget Sound steelhead, coho, and coastal cutthroat. Due to its small size, the culvert also hinders the downstream transport of large wood, thereby depriving the lower 2.4 miles of Siebert Creek of this important habitat-forming material.
Benefit to Salmon:
Siebert Creek steelhead and coho stocks are both imperiled. The project addresses this condition by opening approximately 75% (7.6 miles) of the stream's anadromous habitat to unimpaired accessibility for both stocks. The project will also produce habitat benefits to the lower 2.4 miles of Siebert Creek by restoring the downstream transport of large wood. This culvert is the last anthropogenic impediment to fish passage in Siebert Creek.