South Fork Eel River Watershed Studies (Humboldt and Mendocino Counties)

The 689 square mile South Fork Eel River watershed, located within Mendocino and Humboldt counties, is one of five priority stream systems selected as part of the California Water Action Plan effort. Periods of low flow limit the hydrologic connectivity of the riverine habitat and raise water temperatures. This is of critical concern for at risk salmon and steelhead species which reside in the watershed including the Southern Oregon/Northern California Coast Coho Salmon, California Coastal Chinook Salmon, and North Coast steelhead.

To address the California Water Action Plan, the Department has conducted several studies in the South Fork Eel River watershed. Watershed-wide flow criteria were determined using a combination of site-specific methods and functional flows to support steelhead life stages, maintain natural flow patterns, and support the ecosystem throughout the watershed. The study in Redwood Creek used a one-dimensional modeling approach to combine data on river hydraulics, species- and life-stage-specific habitat preference, and physical habitat modeling to determine instream flow needs for rearing salmonids. Site-specific habitat suitability criteria were developed through extensive surveys in Hollow Tree Creek, tributary to the South Fork Eel River.

The South Fork Eel River study components are complete and technical reports, appendices, calibration reports, and supporting materials are available below.

Resources

• Watershed-Wide Instream Flow Criteria for the South Fork Eel River (PDF)
• Instream Flow Evaluation: Juvenile Steelhead and Coho Salmon Rearing in Redwood Creek, Humboldt County (PDF)
  • Appendices to Instream Flow Evaluation: Juvenile Steelhead and Coho Salmon Rearing in Redwood Creek, Humboldt County (PDF)
  • Hydraulic Model Calibration Report for Instream Flow Evaluation: Juvenile Steelhead and Coho Salmon Rearing in Redwood Creek, Humboldt County (PDF)
• Habitat Suitability Criteria for Juvenile Salmonids in the South Fork Eel River Watershed, Mendocino and Humboldt Counties (PDF)
  • Appendices to Habitat Suitability Criteria for Juvenile Salmonids in the South Fork Eel River Watershed (PDF)
• Redwood Creek Flow Monitoring and Unimpaired Flow Estimation Report (PDF)
• South Fork Eel River Study Plan (PDF)