[Screenshot from report]
Salmon Creek is the third largest tributary to Humboldt Bay. As the name implies, Salmon Creek historically supported significant runs of coho (silver) salmon, steelhead and coastal cutthroat trout, as well as chinook (king) salmon and pacific lamprey.
The Salmon Creek delta was historically tidal salt marsh with a mosaic of slough channels. However, these lands were reclaimed for grazing during the early 1900’s through construction of dikes and levees, draining of salt marshes, straightening or relocation of stream channels, and installation of tide-gates to eliminate tidal influence. After these lands were acquired by Humboldt Bay NWR in 1988, management plans identified Salmon Creek as needing habitat improvements to reestablish estuarine and off-channel habitat. Off-channel habitat consists of sloughs, ponds and oxbows adjacent to the main channel that naturally would have slower water velocities, moderately higher temperatures and more large wood and food where fish (especially salmonids) can spend time while they make the physiological transition from a freshwater animal to saltwater animal. In comparison to pre-1900’s conditions, almost all rearing habitat in the lower portion of Salmon Creek has been lost.
The Refuge initiated efforts to improve fish access and habitat for Salmon Creek in the early 1990’s. One of the first projects was adding a small opening (“fish door”) to one of the flaps on the tide gates. This slightly improved fish passage and allowed some minor tidal exchange upstream of the tidegate, creating a small muted estuary inside the levees. In 1993, the refuge dug a new channel, re-establishing channel sinuosity and complexity to replace a portion of the lower channel that had been ditched and straightened. While this improved habitat, further restoration was needed to increase tidal circulation, improve fish access, and improve hydrology, fish access, and habitat for estuarine dependent species.