Headwater Mercury Source Reduction Strategy

The source and transport of mercury in Sierra Nevada watersheds, from hydraulic mine sites to foothill reservoirs and beyond, has detrimental implications for ecosystem resiliency and community health. The Headwater Mercury Source Reduction (HMSR) Strategy works to identify, assess and mitigate these impacts.

 “The work you do makes a big difference…your voice is heard and the work that you all are doing of bringing together science driven public policy and focusing on the local scale that then can be scaled to the entire Sierra is incredibly valuable.”

Jared Blumenfeld, CalEPA Secretary, at The Sierra Funds Fall 2020 HMSR Workshop

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One of the most persistent and widespread impacts of the California Gold Rush is mercury contamination. Mercury is transported off of hydraulic mine-impacted lands in headwater forests to downstream aquatic environments including reservoirs where it can methylate, enter the food web, and biomagnify and bioaccumulate in fish. The consumption of mercury-contaminated fish is the primary pathway of human exposure and a threat to public health.


In 2017, The Sierra Fund (TSF) launched the Headwater Mercury Source Reduction (HMSR) Technical Advisory Committee (TAC) and HMSR Strategy. The HMSR Strategy is a living document articulating a cohesive framework for collaboration on projects that address four key mercury targets: (1) Hydraulic Mines and Mine Features, (2) Mercury in Forest and Land Management, (3) Mercury-Contaminated Sediment in Reservoirs, and (4) Mercury Exposure via Fish Consumption.


In 2016 the Mercury Strategy Synthesis concluded that no efforts to mitigate mercury in the San Francisco Bay-Delta would be successful without upstream source control. The Sierra Fund’s HMSR project stepped in to fill a critical information gap, providing a vehicle for regional and topical experts to inform and prioritize actions associated with addressing headwater sources of mercury. The HMSR Strategy documents the evolution of a scientific approach for mercury mitigation projects with Sierra to sea benefit.

Next Steps

The Sierra Fund will work with a growing network of collaborative partners to implement the Headwater Mercury Source Reduction Strategy. Specific activities are planned annually to move toward Strategy implementation. The evaluation of techniques used to implement projects will facilitate the ongoing identification of best-practices for assessment and remediation. The Sierra Fund will integrate lesson’s learned into the HMSR Strategy document and share this information with regional and state leaders with the aim of encouraging others to extend the implementation of the Strategy and comprehensively address California’s longest neglected environmental problem, mercury.

Project Funders

Bella Vista Foundation
Campbell Foundation
Resources Legacy Fund
True North Foundation