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

The 689 square mile South Fork Eel 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.

In order to determine what flows will help protect and conserve these populations, it is necessary to understand which specific factors are important for survival and growth at each of their life stages. Some key questions include:

  • What habitat is available during periods of low flow and is it sufficient for juvenile growth and survival?
  • What are the expected flows throughout the year and how do they influence temperatures?
  • What flows are necessary to remove fine sediments from spawning gravels where they inhibit egg incubation?
  • What flows will support and enhance the growth of benthic macroinvertebrates which are an important salmonid food source?

In order to answer these questions, surveys must be performed and data collected. The Instream Flow Program anticipates performing various actions at locations within the South Fork Eel watershed including mapping the existing habitat, performing streamflow measurements, monitoring water temperature, and conducting fish habitat use surveys.


 South Fork Eel River Map - linked file opens in new window
Click map to enlarge.