Prior to the California Gold Rush, cool, contaminant free rivers flowed from the headwaters to the sea and sustained life for indigenous communities and wildlife. Today, the Sierra Nevada is the source of 60% of California’s developed water supply, but the rivers that deliver this water and the cultural lifeways they support are in peril. The Sierra Fund’s focus on rivers seeks to revitalize First Nation resilience, restore critical riverine habitat for wildlife, and regain efficient and effective water storage capacity behind existing impoundments.

“Projects in the Sierra Nevada that seek to address opportunities for fish to migrate upstream and to restore water storage capacity must acknowledge the historic context of “what happened here” and work with the unique and pervasive landscape-level features that shape headwater ecosystems. Specifically, this work must take into account antiquated debris control dams built to hold back hydraulic mining waste and the need for reservoir sedimentation maintenance activities that abate ongoing mercury contamination.”

Carrie Monohan, Ph.D., Program Director


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The evolution of California’s natural water system into a vast infrastructure designed for human-directed conveyance began during the early Gold Rush when the miners built extensive water diversion networks to work their individual claims. As mining techniques advanced, more and more water was transported from rivers and streams to facilitate the recovery of gold. Rivers and streams were systematically diverted from natural pathways and directed into aqueducts, flumes, ditches and reservoirs upstream of mines to ensure a continuous supply water for the hydraulic monitors and sluices vital to gold extraction. Equally complex systems were constructed downstream of mines to convey waste away.

Rivers and streams were used to carry waste from the mines in the form of sediment and rock debris (hydraulic mines) and tailings (hardrock mines), with waste often impounded downstream in reservoirs built for this purpose. Due to the extensive use of mercury during gold processing, mine waste was often highly contaminated. The massive volume of sediment moved by hydraulic mining and the use of mercury polluted the rivers, streams, and reservoirs of the Sierra; downstream channels; the San Joaquin Delta; and the San Francisco Bay.

Our Vision for healthy, abundant Sierra Nevada riverine systems

The demand for water in California increases with population density and access to water is key to maintaining the resiliency of communities and fisheries in the Sierra Nevada and downstream. Aging infrastructure and ongoing sediment releases from legacy hydraulic mines in the headwaters impacts the quantity and quality of water available to downstream users and the ability of anadromous salmonids to migrate upstream to breed.

Riverine restoration is needed throughout the Gold Country to restore river health and function and to address issues of fish habitat, fish passage, and reservoir storage capacity. Restoration of longitudinal and latitudinal connectivity between rivers and floodplains must be done with an eye to solving multiple connected issues and must be informed by the context of legacy mercury contamination, antiquated Gold Rush-era infrastructure and traditional cultural lifeways.

Key to our approach is engaging the First Nations of the Sierra, on whose ancestral homelands projects are planned, so that meaningful actions that work to restore ecosystem resiliency are executed in tandem with efforts to support community resiliency.