Effects of increased ground-water withdrawals on water levels, water quality, and wetland areas, Tooele Valley , Utah

Project Number: 97169C5
Cooperating Agencies: Tooele County and Tooele City
Project Chief: Bert Stolp, USGS Salt Lake City, Utah
Project Period: 2002-2006

Problem: Tooele Valley is experiencing rapid population growth. Ground water is the sole source of drinking water in Tooele Valley and supplies water to wetlands in the northern part of the valley. Several areas in the valley have ground water of poor quality. These areas contain ground water with concentrations of TCE, arsenic, nitrate, and total dissolved solids that make the water unsuitable for public supply without expensive treatment. Recent data collected by the USGS has identified new ground-water resources in some of the consolidated rock units of the Oquirrh Formation in the southeast part of the valley and on South Mountain at the southern end of the valley. The long-term sustainability of this newly identified ground-water resource is unknown. Protection of ground water suitable for public supply in the consolidated rock and the basin fill is important to meet existing and future water needs of residents of Tooele valley. The effect of developing this resource needs to be understood in order to manage and protect the remaining good quality water and to minimize effects on existing water rights and wetland resources.

Objective: The objective of this study is to provide Tooele County and City with information to help determine what effects future ground-water development will have on the existing water levels, water quality, and wetland areas in Tooele Valley. Specific objectives of the study determine the most optimal ground-water withdrawal configuration in order to minimize impacts on water levels, water quality, and wetland resources in Tooele Valley.

Relevance and Benefits: The increased demand for water in Tooele Valley will change the location and increase the amount of withdrawals within the basin fill and adjoining consolidated rock. Changing water-use patterns has the potential to effect water quantity, and more importantly, water quality. This cooperative study between the U.S. Geological Survey and Tooele County, Tooele City, and other interested parties will increase the understanding of the complex hydrologic setting in Tooele Valley. Additionally, proposed enhancement of the existing regional Tooele Valley ground-water flow model will provide a tool that can be used to help manage impacts to the water resources.

Approach: Specific work items include (1) defining the distribution of ground-water recharge from mountain front runoff using snowmelt runoff models and streamflow records, (2) analyzing water samples for isotopic composition to help determine sources of recharge and ground-water velocities, (3) conducting aquifer tests to estimate hydraulic properties of the consolidated rock, (4) modifying the existing ground-water flow model of Tooele Valley to incorporate the adjacent consolidated rock of the Oquirrh, South, and Stansbury Mountains and new data collected during the study, and (5) use the model to assess the effects of continued and increased withdrawals from different aquifers zones in the valley.

Products: All data and results of study will be documented in a USGS report. The data set, including Geographic Information System data layers will be made available to the cooperator. The numerical ground-water flow model will be archived and also made available to the public.

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U.S. Department of the Interior | U.S. Geological Survey
URL:http://ut.water.usgs.gov/newUTAH/Programs/TooeleValley.html
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Page Last Modified: Wednesday, 10-May-2006 16:49:42 EDT