Duck Valley Biological Intergrity

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Since May 2007, the U.S. Geological Survey (USGS) and Shoshone-Paiute Tribes have worked together to evaluate mercury concentration in fish and macroinvertebrates in Duck Valley reservoirs and the Owyhee River. These water resources are valued trout fishery resources to the Tribes for commercial and recreational benefits that may be threatened by mercury contamination.

The sources of mercury are not well-quantified; however, they likely include coal-fired power plants, mining operations, and natural sources. This inorganic mercury is converted to organic forms by a process called methylation. The methylation process is improved in shallow reservoirs and wetland habitats and fish in those habitats are particularly susceptible to bioaccumulation (mercury accumulating in tissue). Under these conditions, methylmercury concentrations in fish can be more than a million times greater than concentrations in water.

2007-Biennially: Assessing Mercury Levels in Fish Tissue, Duck Valley Area Reservoirs, Idaho and Nevada

Problem: Decades of mining and other industrial activities near the Duck Valley Reservation deposed inorganic mercury into the fisheries of the Shoshone-Paiute Tribes. The Tribes were concerned that mercury methylation and bioaccumulation in the food chain might pose a risk to their people and their natural resources

Study Approach: USGS and Tribal biologists collected rainbow trout from three Tribal reservoirs, a reservoir outside the reservation, and from a hatchery transport vehicle. Tissue samples from these fish were anaylzed at the USGS Mercury Research Laboratory in Middleton, WI. Read more

 

2008: Assessing Fish Community Health in the Owyhee River, Idaho and Nevada

Problem: Because the 2007 reservoir study indicated elevated mercury levels in fish, the Shoshone-Paiute Tribes wanted a better understanding of the heavy metal contamination throughout the watershed. The Tribes have been monitoring the Owhyee River's water quality, but needed more information about area fisheries to effeciently manange resources on the reservation.

Study Approach: USGS biologists collected fish and macroinvertebrate samples from the Owyhee River in Idaho and Nevada. The fish tissue results will provide baseline information about the occurrence and distribution of mercury in fish. The macroinvertebrate results will be used to determine if more studies are needed. Read more