Cispus River Conceptual Design of Off-channel Habitat

Location: Clark County, WA
Client: Lower Columbia Fish Enhancement Group

The Lower Columbia Fisheries Enhancement Group wanted to provide Coho and Chinook salmon refuge from harsh winter conditions in the Cispus River. Otak scientists provided analysis to help determine optimal locations for establishing off-channel habitat that would be fed by groundwater during most of the year, and by floodwater during high flow events. The alternatives included two secondary channels on the main channel’s floodplain. Otak assessed the viability of each alternative by monitoring water level and temperature to determine the likelihood of engaging suitable flow conditions without stranding juvenile salmonids.