Mendocino
County Migration Barrier Inventory Report
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PDF File (856 KB)
Mendocino County Migration Barrier Culvert Catalog
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PDF File (29,087 KB)
Mendocino County Prioritized Ranking Matrix
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Dark Gulch crossing at Orr Springs Road (above) is located
in the South Fork. Big River Watershed and is ranked as the 7th highest priority
project in Mendocino County.
The current crossing is extremely undersized and is estimated to overtop Orr
Springs Road on about a 22-year storm discharge.
FishXing software determined that the culvert is a total barrier for adult
coho salmon and steelhead, as well as all age classes of juveniles, due primarily
to excessive velocities over steep slope, lack of depth at lower migration
flows, and leap required to enter culvert. The engineering design and permitting
activities for Dark Gulch will be completed in 2005 with funding through the
California Coastal Conservancy. The preferred treatment for this site would
be a properly-sized bridge or pipe-arch set on concrete footings.