Off-Channel Salmonid Habitat Design for Freshwater Creek
RCAA received a grant from the California Department of Fish and Wildlife (CDFW) Fisheries Restoration Grants Program (FRGP) to develop engineered designs plans to provide habitat enhancements and improve juvenile salmonid access into two existing off channel habitat features in lower Freshwater Creek, a major tributary to Humboldt Bay. The proposed project will restore and provide access to a total of 0.225 acres of off-channel non-natal winter rearing habitat for juvenile coho salmon. This area will be low gradient, low velocity, complex habitat sought out by juvenile salmonids for rearing and high-flow refugia. The off-channel habitat will be restored within a historical meander bend of Freshwater Creek and an alcove formed by floodplain drainage that have since become disconnected with the main channel.
Off-channel habitat, including side-channels and ponds, provides highly desirable overwintering habitat for juvenile coho salmon throughout the Pacific Northwest and California. Coho at all life stages appear to be best adapted to, and show preference for, slower moving water. This preference for slow moving water is most prevalent during very young fry and overwintering life stages. Off-channel habitats produce higher rates of survival than other available habitats, such as cobble substrate and undercut banks.
RCAA employed the services of Michael Love & Associates, Inc. (MLA) to conduct hydrologic and water quality monitoring of the two restoration sites and develop engineering designs. A geologic investigation was performed by Pacific Watershed Associates (PWA) to characterize the subsurface soils within the project area.