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	Investigations of Sediment-water Interactions in Western U.S. Water Bodies
BENTHIC FLUX OF METALS AND NUTRIENTS PROJECT

Photos of historical hydraulic mining scares and sampling on the reservoir

Camp Far West Reservoir, California

In the northwestern Sierra Nevada, the historic, routine use of mercury for processing gold ore had resulted in mercury contamination and bioaccumulation of methylmercury within major watersheds. Previous studies by the USGS scientists from the Caolifirnia District demonstrated that: (1) Sierra Nevada watersheds export mercury to the Bay-Delta via the Sacramento River, and (2) fish from five reservoirs in the Bear River, Deer Creek and South Yuba River watersheds (among the most intensely mined) have elevated tissue-concentrations of mercury (Mercury Contamination in California Fact Sheet).

The evaluation and development of remedial actions, including Total Maximum Daily Load (TMDLs), within Sierra Nevada watersheds is highly dependent on our understanding of controls of methylmercury production, transport and bioaccumulation. The relative contributions of mercury and methylmercury loads from the Bear, Yuba, and Feather rivers are poorly known; present estimates are based on scanty data from inconsistent flow regimes. This study is part of a collaboration with the USGS California District and the California State Water Resources Control Board to identify and quantify factors regulating mercury methylation, demethylation, and bioaccumulation in Sierra Nevada watersheds. In part, initial, direct determinations of total methyl-mercury benthic flux are being determined to: (1) evaluate the potential importance of sediment-water interactions in Camp Far West Reservoir along the Bear River, relative to other sources and sinks within the watershed, and (2) to identify processes that may regulate the spatial and temporal variability of those benthic interactions.

Related Publications:

Sediment-Water Interactions Affecting Dissolved-Mercury Distributions in Camp Far West Reservoir, California
(U.S. Geological Survey Water Resources Investigations Report 03-4140)
http://pubs.usgs.gov/wri/wri034140/pdf/WRI034140.pdf

Mercury Contamination from Historical Gold Mining in California
http://pubs.usgs.gov/fs/2005/3014

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Last modified: May 6, 2016