Mistakenly named in 1850 for eel-like lamprey, the Eel River begins its 196 mile journey in Northern Lake County interrupted by the 138 foot Scott Dam forming Lake Pillsbury. Up to 84,000 acre feet of water running down the southern flank of 6,740 foot Bald Mountain is pooled here like a headwaters lake. The lake forms an unusual bond with the land because it floods a gravel filled valley where low flows would be sub-surface with few pools.
This lake ecosystem established in 1922 is now home to fish, river otter, mink, Tule Elk, eagles and other water-dependent wildland species. It provides fire protection and also recharges groundwater to resurface downstream even without discharges from the dam. High energy discharges keep the upper stream reaches clean of fine sediment by sorting the material into sand bars and gravel stretches needed for spawning salmonids. In earlier times, much of this chore was accomplished by snowpack melt.
The value of this water has increased tremendously since the dam was built because much of the river and tributaries have degraded significantly over the decades after European arrivals. Composed of sedimentary rock and soils, the watershed is easily eroded where 20th century logging and landuse practices increased its vulnerability to high intensity storms. Fortunately, early Army Corp of Engineer’ proposals to add dams to the Eel were denied because the pineapple-express storm of 1964 delivered 105 million tons of debris that could have filled them in one season. The 940,000 cu. ft. storm flow, at 70 feet above flood stage destroyed 10 towns and 20 bridges burying the channel with sediment.
This single storm and several more in the 20th century changed the morphology of the otherwise storm-adjusted channel and almost wiped out the spawning grounds for native salmon and steelhead causing the already overfished populations to crash. Only large storms soaking a more stable watershed over many decades will naturally improve channel conditions. Without Lake Pillsbury, a headwater’s lake might have been proposed to replace the snowpack melt to help stabilize the salmonid populations in the upper Eel. Lake Pillsbury’s upper watershed presence now has turned to one of opportunity.
The pressure on native fish is extreme with wells drawing down the water table, agriculture pulling water during the dry summer, the introduction of warmwater predator fish and towns with year-round demand dry the river. Adding to the problem, the Potter Valley project using the downstream Cape Horn dam diverts water through a tunnel to the Russian River producing electric power and increases a dependent agriculture and population. Lake Pillsbury does not divert but provides backup water for that enterprise. This splitting of flow decreases the water available to downstream Eel habitats.
Today, the Potter Valley Project is being abandoned by its operator PG&E and many political groups are voicing opinion about the fate of dams on the Eel. Both removal or retention of the dams are being discussed without full appreciation for native fish needs throughout the long, very degraded Eel River or the tremendous value of the headwaters lake ecosystem formed by Scott Dam. Arguments calling for the restoration of the river by just removing dams are a soundbite chant hiding a true solution for the damaged ecosystem. In truth, removing Scott Dam allows fish access to very little additional habitat compared to all the habitats benefiting from it.
A better approach is to prioritize the Eel’s channel restoration and Lake Pillsbury discharges using salmonid habitats as the health indicator. All competing interests for the water would be compelled to jointly keep the system healthy before making demands. But to accomplish this, winter water offstream storage is needed in both Russian and Eel watersheds to support groundwater recharge, agriculture and towns. The diversion tunnel from the Eel should be used only during extreme flows and the Russian River’s Lake Mendocino capacity increased to act as a headwaters lake supplying that watershed. Since the 2018 fire season, upper montane watersheds on Federal lands should be managed to increase the groundwater percolation and flow into both systems.
A full river restoration requires more than orchestrating the political positioning of stakeholders. It requires a commitment by everyone to the future of the natural ecosystem by developing new priorities to meet the challenges created by the past. As homage to a new beginning, maybe changing the name to Lamprey River is also in order.