West Fork evaluated four potential barriers in the lower 1,700 feet of Williams Creek, tributary of the Cedar River (WA) for Seattle Public Utilities to determine the likelihood for passage by Chinook, steelhead, coho and resident trout. The goal of this project was to assess the suitability of Williams Creek for restoration activities after construction of a fish ladder that assured fish passage through Landsburg Dam lower on the Cedar.
Our analysis included a detailed habitat assessment of the likely transit paths through the barriers by both jumping and swimming. Results suggested that the natural obstructive features in Williams Creek were complex and presented significant challenges on most flows.
While existing hydraulic methods of analysis were informative, they did not produce unequivocal answers owing to the multiplicity of factors that influence passage including, variability in discharge, fish size, uncertainty about likely transit routes and short term erosional changes at the features themselves.