Tooele Valley, Tooele County, Utah, is a mostly rural area at the south end of Great Salt Lake experiencing a rapid increase in residential development, resulting in less agricultural land use. While most of the development in the incorporated areas of Tooele Valley uses municipal water sources, principally wells, development in the unincorporated areas primarily relies on single-family domestic wells. This change from agriculture to domestic water use could significantly decrease the amount of ground water discharged from the confined aquifer system, where most wells are completed, to the shallow unconfined aquifer system, which provides water to springs and wetlands in ground-water discharge areas. Additionally, drought conditions over the past six years have reduced the amount of recharge to ground-water aquifers across the state, also impacting Tooele County?s wetlands. Also, in early 2005, the elevation of Great Salt Lake declined to near its historic lowstand reached in 1963. Tooele County is in the process of creating a Special Area Management Plan (SAMP) for the wetlands in Tooele Valley to balance development with wetland conservation.

The purpose of this study is to use existing stateof-the-art steady-state and transient ground-water-flow models developed by the U.S. Geological Survey (Lambert and Stolp, 1999) to simulate the hydrologic effects on wetlands from various recharge rates and projected ground-water withdrawals at various projected Great Salt Lake levels. These simulations can be used to assess potential threats on wetlands from increased ground-water withdrawals and drought, and provide a basis for (1) implementing restrictions on domestic withdrawals, (2) assessing water needs for wetland preservation, and (3) encouraging the development of water conservation programs.

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