The Salt River Basin is located in Humboldt County, 15 miles south of Eureka, CA and encompasses approximately 47 square miles (30,425 acres). The Salt River Basin is comprised of the Wildcat tributaries (12,775 acres) and the alluvial delta (17,650 acres). The headwaters of the Salt River Basin reach an average elevation of 800 feet with maximum elevations of 1,750 feet. The Salt River Basin has a moderate climate with an average annual temperature of 52°F. Average annual precipitation in the region is 44 inches, 90% of which occurs from late fall till early spring.
The Salt River Basin is part of the Eel River Delta and Estuary, although its role as an estuarine slough has lessened over the years. At one time the Salt River was a significant part of the Eel River Estuary and was a tidal stream at all times. It is thought that the Salt River occupies a former channel of the Eel River that was left behind as the dominant channel of the Eel River migrated north across the delta over centuries of change. Historically (pre-1860’s), the Salt River, contained four anadromous freshwater tributaries, seven smaller drainages and significant estuarine tributaries/sloughs.
The vast majority of the Salt River Delta is now in agricultural production. The Wildcat Hills are managed by numerous landowners for pastoral land use and small scale timber production. Residential development upon the Salt River Delta and the Wildcat Hills will likely increase which is can be problematic due to an associated increase in road construction and a change in drainage patterns.
The Salt River is located in an area where natural processes create a dynamic and ever-changing aquatic system. These natural processes include: loosely consolidated sedimentary rock formation in the Wildcat Hills that are susceptible to large scale landslides; steep slopes, and a high occurrence of earthquakes. The project area is also influenced by tectonic subsidence and uplift and by changes in sea level. Other natural processes that influence the Salt River include intense winter rainfall. A complex interaction of a century and a half of land use actions combined with natural conditions and events have significantly altered the Salt River and its ecological function.
Residents that live and work along the banks of the Salt River are plagued by annual flooding and ponding, which has significant economic impact for those directly affected. Due to extremely high rates of sedimentation the mainstem Salt River (river mile 7.5) channel completely filled with sediment and has caused a diversion of water into the outlying land. The eastern portion of the Salt River Basin became diverted to flow into the Old River which represents a 42% reduction in Salt River Basin size. At this time, Williams Creek no longer flows into the Salt River and is no longer accessible to salmonids.
Considering the ecological significance of the Salt River within the Eel River Delta and the need to alleviate increasing flooding issues within the region, the CDFW’s Coastal Watershed Planning and Assessment Program completed the Salt River Watershed Assessment in 2005 as one of the first steps of a renewed basin restoration effort. Please see the Salt River Restoration Project link for details on the background on the project, the restoration work completed, the project’s accomplishments, and future direction of project.