Sonoma County Fish Passage Projects
Client: Sonoma County Public Works
Waterways assisted the Sonoma County Department of Transportation and Public Works with planning and design services to address two fish passage barriers associated with stream crossings on County roads. The sites consisted of two large concrete box culverts that were limiting fish passage to high quality spawning and rearing habitat located upstream. At each of these culverts, the natural streambed had incised to at least 4 feet below the culvert outlet, resulting in a partial barrier to migrating salmonids. The design solution included structural retrofit of the culverts using concrete baffles, and the construction of a roughened channel to aggrade the stream profile sufficiently to eliminate the passage barrier. Work consisted of topographic mapping, hydrologic and hydraulic modeling, and preparation of preliminary and final design drawings and specifications.