The Eel River watershed is a coastal tributary located in the California Coastal Ranges that stretches across five counties: Humboldt, Trinity, Mendocino, Glenn, and Lake. With a drainage area of approximately 3,680 square miles, the Eel is the third largest watershed in California, following the San Joaquin and the Salinas River. The Eel River itself stretches approximately 196 miles long and empties into the Pacific Ocean, about 10 miles south of Humboldt Bay and the city of Fortuna.
The Eel River basin supports temperate coniferous forests consisting largely of Coastal redwood, Douglas Fir, and western hemlock. Historically and currently the area is a significant source for timber. Current common land use includes logging, grazing, agriculture, and recreation.
The Eel River is the most dynamic water system in California, with discharge varying by over 100 times depending on the season. This high variability is a result of the region’s unstable geology and heavy rainfall. It is also the third largest salmon and Steelhead producing river systems in California, after the Sacramento and Klamath River, with over a million fish spawning annually.
The Eel has minor river modifications, including two hydroelectric dams: Scott Dam and Cape Horn Dam. The river also provide water for groundwater recharge, agriculture, and municipal water supplies. In 1981, the Eel was declared a National Wild and Scenic River System under the Wild and Scenic Rivers Act of 1968. This act ensures the preservation of rivers with high natural, cultural, and recreational value in a free-flowing condition and therefore prevents any future damming of the Eel.
A more recent, notable impact to the Eel is water diversion for both legal and illegal cannabis cultivation. Environmental impacts appear substantial, but are difficult to quantify due to illegal diversion and lack of enforcement.