Proportion of Days with Stream Flows above Maximum Weighted Usable Area

Physical Habitat Simulation Modeling (PHABSIM) is a methodology often used in an effort to quantify the relationship between stream flow and habitat availability for specific life stages of various fish species. This method provides estimates of Weighted Usable Area (WUA), an index of habitat availability, at varying river flow levels. For spawning salmonids, maximum WUA is typically provided by a relatively narrow range of flows. In designing the Cedar River fall flow regime, scientists considered maximization of WUA in addition to other potentially important factors such as maximizing cumulative spawning habitat and recruitment of habitat in areas with lower risk of subsequent redd scour.

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