Big Cedar Culvert Design

The Idaho Soil and Water Conservation District (ISWCD) designed a culvert replacement at the mouth of Big Cedar Creek, a tributary to Clear Creek in the Middle Clearwater River watershed. The existing culvert is a barrier to juvenile salmonids and a seasonal barrier to adult salmonids due to a four-foot drop at the outlet during adult upstream migration. This drop, along with the velocities inside the culvert during high flows makes it impassable for most of the adults returning to Big Cedar Creek. A 24-foot span arch pipe culvert was designed to replace the culvert to allow for fish passage to 8 miles of Big Cedar Creek. The designs were accepted by NOAA fisheries. Permitting, ESA compliance and Cultural Resource review is underway. Installation will occur in 2024 using secured other funding sources.

When the implementation of the Big Cedar Culvert Design is completed, this project will benefit ESA-listed steelhead by opening up full access to over eight miles of high-quality habitat suitable for both adult spawning and juvenile rearing. The high-quality habitat that exists upstream of this project site is ideal for steelhead and consists of low to moderate stream slope that contains gravels and cobbles suitable for spawning, pools for juvenile rearing, and cool water temperatures that will provide summer refugia from the warmer temperatures found downstream of this site.