The Eel River is located in northern California, approximately 200 miles north of San Francisco at latitude 40° 38' 32" N, longitude 124° 18' 43" W. The Eel River catchment lies predominantly in Humboldt and Mendocino counties and also extends into Trinity, Glenn and Lake counties.
The mainstem Eel River is approximately 197 miles in length and receives flow from 832 tributaries - adding up to 3,526 miles of stream. It is the third largest river in California with a drainage basin of 3,684 square miles (CDFG 1997). Elevations on the mainstem range from sea level at the mouth to over 6,700 feet at the headwaters. Four principle tributaries are the Van Duzen River, North Fork Eel River, Middle Fork Eel River, and South Fork Eel River.
Because the Eel River catchment is large and complex, the CWPAP team has divided it into several basins for assessment. This report assesses the Lower Eel River Basin.
The Lower Eel Basin assessment area is composed of less than 5% of the entire Eel River catchment at approximately 172 square miles and is defined as the watershed area from the mouth, upstream approximately 21 miles. As the Lower Eel Basin comprises the most downstream and depositional section of the entire Eel River catchment, any discussion of watershed processes within the basin must be considered in this larger context.
Even though the Eel River remains the third largest producer of salmon and second largest of steelhead in the state, overall salmon runs in the Eel have dramatically declined (CDFG 1997 [salmon and steelhead action plan]). Defining and quantifying the causes of this decline can be difficult, though most surely they are a result of cumulative effects of human impacts in a dynamic system.
Anadromous salmonids found in the Lower Eel River Basin include:
California Coastal (CC) Chinook Salmon (Oncorhynchus tshawytscha) - status: threatened (federal listing in 1999);
Southern Oregon/Northern California (SONCC) coho salmon (Oncorhynchus kisutch) - status: threatened (federal listing in 1997 and state listing in 2005);
Northern California (NC) steelhead trout (Oncorhynchus mykiss) – status: threatened (federal listing in 2000); and
Coastal cutthroat trout (Oncorhynchus clarki).