UNM Hydrogeoecology Research Projects :

Funded by the U.S. Geological Survey and Washoe County, Nevada

Investigator: Michael E. Campana

 

Project Description

The Truckee River, which rises at Lake Tahoe, California, and terminates at Pyramid Lake, Nevada, has an importance far beyond its small size. It provides much of the water supply for the Reno metropolitan area and irrigated agriculture in the Fernley-Fallon area east of Reno, supports recreational activities, and nourishes the once world-renowned Pyramid Lake fishery. The latter role was reduced substantially by the Newlands irrigation project, the first project completed by the Bureau of Reclamation in the early 1900s. Since that time the level of Pyramid Lake has dropped precipitously (about 80 feet) and the fishery has been decimated. A double-edged sword is also present: not only does the irrigation diversion reduce the flow in the river, but some of the irrigation water, now with high total dissolved solids (TDS) and nutrient content, also returns to the river as subsurface flow and degrades the river's water quality and, presumably, the stream ecosystem. A recent initiative, driven partly by the Endangered Species Act, calls for the retirement of some of the irrigated land which would decrease the amount of diversion from the river and presumably improve the river's water quality by reducing the irrigation return flow. But how much are the Truckee's quality and ecosystem actually degraded by the return flow? Could some of the degradation occur via subsurface flow from the local geothermal system or flow that has moved through evaporite-rich lacustrine formations? What are the sources of the salts in the irrigation return flow? How much would the flow to river be reduced? These and other questions, whose answers will have important ramifications for river management, will be answered in a multidisciplinary study (hydrology, geology, aquatic ecology, geochemistry, etc.) being conducted by the Desert Research Institute, the University of Nevada-Reno, Washoe County, and the University of New Mexico. Our role at UNM will be to: develop numerical ground-water flow and transport models for the Fernley agricultural area; help characterize surface-water - ground-water exchange; and use environmental isotopes to help delineate sources of salts and water.

Personnel

Michael E. Campana, PI

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Page updated January 14, 1999 by Richard K. Mott

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