Nevada/Utah Regional Groundwater Model and Impact Analysis
U.S. Department of Interior

West Yost is developing a groundwater model for eastern Nevada and western Utah. The work is being conducted jointly for the U.S. Fish and Wildlife Service, U.S. Bureau of Land Management, National Park Service, and U.S. Bureau of Indian Affairs. The model covers an area of about 25,000 square miles. The model will be used by theses agencies to assess the impacts of proposed groundwater exports from the model area. 

Each agency is represented by technical advisors that provide review and input of our work products. We participate in regularly scheduled conference calls with DOI representatives and periodic workshops with the DOI representatives and other involved agencies including the U.S. Geological Survey and Utah Geologic Survey. The model will be used by these agencies to assess the impacts of proposed groundwater exports from the model area. The model area is within the Great Basin physiographic and geologic province. The model area is characterized by regional carbonate, volcanic, and alluvial aquifers that have been impacted extensively by large-scale faulting and folding, and by granitic rocks that have intruded through the carbonate rocks. The faulting and intruded granitic bodies represent important controls on local and regional groundwater flow and on groundwater discharges to large regional springs and extensive acreages of phreatophytes. A groundwater model is being constructed to represent the complexity of those controls.

The model represents the three-dimensionally anisotropic hydraulic conductivity of the groundwater system induced by the tilting or folding of carbonate and volcanic rocks. It additionally represents faults as either or both conduits or barriers to groundwater flow, including the association of large springs with faults. The development of the model has involved the conceptualization of the hydrogeologic setting, the identification and quantification of natural recharge, and the quantification of groundwater use by phreatophytes. These tasks each have extensive GIS and data management elements, including the quantitative analysis of satellite images to assess phreatophyte evapotranspiration. The phreatophyte evapotranspiration is an important component of the water budget calculations.