Supplementary water supplies are needed for a rapidly growing population in southern Nevada. Ground-water resources from basin-fill and consolidated rock aquifers in southern Spring and Snake valleys in eastern Nevada have been identified as a potential water-supply source. These aquifers provide water to springs, streams, wetlands, limestone caves, and other biologically sensitive areas on Federal lands in eastern Nevada, which provide habitat for numerous species of plants and animals, including one species of Federally listed endangered fish.
The National Park Service, Bureau of Land Management, Fish and Wildlife Service, and USDA Forest Service needed geologic, hydrologic, and chemical information to assess the hydraulic connection of basin-fill and carbonate-rock aquifers with surface-water resources and water-dependent ecological features in southern Spring and Snake valleys in eastern Nevada. Understanding these connections is important because pumping of groundwater in Spring Valley or Snake Valley may result in unintended capture of surface streams and/or groundwater discharge to springs in ecologically sensitive areas of southern Snake Valley. The USGS Nevada Water Science Center completed a study in 2011 to provide additional information about the hydrologic effects of water-supply development in southern Spring and Snake valleys on the water resources in southern Snake Valley.
This study was designed to assess the hydrologic effects of water-supply development in southern Spring and Snake valleys on the water resources in southern Snake Valley through four specific tasks:
- Evaluating the distribution, geometry, and hydraulic properties of the Cenozoic sedimentary rocks and coarse- and fine-grained basin-fill deposits by
- drilling new test wells,
- compiling data from existing wells and oil test holes,
- using geologic maps correlated to geophysical surveys, and
- visual inspection of geologic outcrops.
- Quantifying streambed hydraulic conductivity and the volume of water exchanged between groundwater and surface water along selected reaches of Lehman, Baker, and Snake Creeks using
- a combination of surface (on the streambed) and subsurface (1.5 and 3 ft below the streambed) temperature measurements,
- stage at temporary surface-water gages,
- synoptic streamflow measurements (seepage runs),
- temperature and water-level measurements in shallow piezometers installed in the streambed, and
- from multiple-well aquifer tests.
- Determining the source of water to Rowland Spring and Big Springs by
- drilling test wells upstream of each spring,
- collecting water chemistry of water in the wells, creeks, and springs, and
- analyzing the results using geochemical mixing models.
- Estimating the quantity of groundwater flow across the topographic divide (Limestone Hills) that separates southern Spring Valley from northern Hamlin Valley by
- contouring water levels measured in new and existing wells in southern Spring and Snake Valleys and
- estimating the volume of subsurface flow beneath the Limestone Hills using Darcy's Law
Background
Southern Nevada relies on the Colorado River for most of its water supply. Supplementary water supplies are needed to offset a persistent drought in the Colorado River Basin and a rapidly growing population in southern Nevada. Ground-water resources from basin-fill and consolidated-rock aquifers in eastern Nevada are a potential water supply source. These aquifers provide water to springs, streams, wetlands, limestone caves, and other biologically sensitive areas on Federal lands in eastern Nevada, which provide habitat for numerous species of plants and animals, including one species of Federally listed endangered fish. These water-dependent features also are visited and enjoyed by anglers, hunters, and tourists, including numerous visitors to Great Basin National park. A dearth of hydrologic data precludes a definitive evaluation of the potential effects of ground-water development on these water-dependent natural resource features.
Several sections of surface streams and spring discharge areas in-and-adjacent-to Great Basin National park in Spring and Snake valleys were identified as susceptible to ground-water withdrawals. Additionally, ground-water pumping in southern Spring Valley potentially could capture streamflow and ground-water discharge to springs and Big Springs Creek in southern Snake Valley because previous studies have indicated ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide. Estimates of annual flow across the divide range from 4,000 to about 30,000 acre feet, which is between half to 3 times more than the discharge of Big Springs at the southwestern end of Snake Valley.
Supplementary water supplies are needed for a rapidly growing population in southern Nevada. Ground-water resources from basin-fill and consolidated rock aquifers in southern Spring and Snake valleys in eastern Nevada have been identified as a potential water-supply source. These aquifers provide water to springs, streams, wetlands, limestone caves, and other biologically sensitive areas on Federal lands in eastern Nevada, which provide habitat for numerous species of plants and animals, including one species of Federally listed endangered fish.
The National Park Service, Bureau of Land Management, Fish and Wildlife Service, and USDA Forest Service needed geologic, hydrologic, and chemical information to assess the hydraulic connection of basin-fill and carbonate-rock aquifers with surface-water resources and water-dependent ecological features in southern Spring and Snake valleys in eastern Nevada. Understanding these connections is important because pumping of groundwater in Spring Valley or Snake Valley may result in unintended capture of surface streams and/or groundwater discharge to springs in ecologically sensitive areas of southern Snake Valley. The USGS Nevada Water Science Center completed a study in 2011 to provide additional information about the hydrologic effects of water-supply development in southern Spring and Snake valleys on the water resources in southern Snake Valley.
This study was designed to assess the hydrologic effects of water-supply development in southern Spring and Snake valleys on the water resources in southern Snake Valley through four specific tasks:
- Evaluating the distribution, geometry, and hydraulic properties of the Cenozoic sedimentary rocks and coarse- and fine-grained basin-fill deposits by
- drilling new test wells,
- compiling data from existing wells and oil test holes,
- using geologic maps correlated to geophysical surveys, and
- visual inspection of geologic outcrops.
- Quantifying streambed hydraulic conductivity and the volume of water exchanged between groundwater and surface water along selected reaches of Lehman, Baker, and Snake Creeks using
- a combination of surface (on the streambed) and subsurface (1.5 and 3 ft below the streambed) temperature measurements,
- stage at temporary surface-water gages,
- synoptic streamflow measurements (seepage runs),
- temperature and water-level measurements in shallow piezometers installed in the streambed, and
- from multiple-well aquifer tests.
- Determining the source of water to Rowland Spring and Big Springs by
- drilling test wells upstream of each spring,
- collecting water chemistry of water in the wells, creeks, and springs, and
- analyzing the results using geochemical mixing models.
- Estimating the quantity of groundwater flow across the topographic divide (Limestone Hills) that separates southern Spring Valley from northern Hamlin Valley by
- contouring water levels measured in new and existing wells in southern Spring and Snake Valleys and
- estimating the volume of subsurface flow beneath the Limestone Hills using Darcy's Law
Background
Southern Nevada relies on the Colorado River for most of its water supply. Supplementary water supplies are needed to offset a persistent drought in the Colorado River Basin and a rapidly growing population in southern Nevada. Ground-water resources from basin-fill and consolidated-rock aquifers in eastern Nevada are a potential water supply source. These aquifers provide water to springs, streams, wetlands, limestone caves, and other biologically sensitive areas on Federal lands in eastern Nevada, which provide habitat for numerous species of plants and animals, including one species of Federally listed endangered fish. These water-dependent features also are visited and enjoyed by anglers, hunters, and tourists, including numerous visitors to Great Basin National park. A dearth of hydrologic data precludes a definitive evaluation of the potential effects of ground-water development on these water-dependent natural resource features.
Several sections of surface streams and spring discharge areas in-and-adjacent-to Great Basin National park in Spring and Snake valleys were identified as susceptible to ground-water withdrawals. Additionally, ground-water pumping in southern Spring Valley potentially could capture streamflow and ground-water discharge to springs and Big Springs Creek in southern Snake Valley because previous studies have indicated ground-water flow from southern Spring Valley into southern Snake Valley through carbonate rocks that outcrop along a low topographic divide. Estimates of annual flow across the divide range from 4,000 to about 30,000 acre feet, which is between half to 3 times more than the discharge of Big Springs at the southwestern end of Snake Valley.