The geomorphic assessment included assembly and analysis of several datasets pertaining to site hydrology, soils, geology and historical conditions. Waterways analyzed the geomorphic landforms of the entire Ukiah Valley to obtain a “big picture” perspective of the channel conditions surrounding the project site. The analyses revealed historic and current processes of erosion and sediment transport, which Waterways extrapolated to estimate future meander activity and potential erosion rates. Waterways then applied this information to develop recommendations for mining setback limits and shoreline restoration treatments.
Our staff worked closely with the Granite Construction, Inc. and NOAA Fisheries to develop a design that minimized impacts to the river environment and wildlife resources. The project design incorporates an overflow weir and “fuse plug” that equilibrates the river and pit water levels while reducing the potential for fish entrapment during lower frequency flood events. Channel restoration designs included the excavation of geomorphically appropriate terraces along Ackerman Creek and the Russian River to improve the riparian corridor, enhance bank stability, and provide high-flow refuge for salmonids.