Summary and Conclusions

Cave Springs are the water supply for the Lehman Caves Visitor Center at Great Basin National Park, which is about 60 miles east of Ely, Nevada, in White Pine County. Cave Springs were investigated to determine if ground water discharging at the springs could be shallow ground water moving through alluvial and glacial deposits associated with nearby Lehman Creek, through the quartzite, through limestone, or some combination of these rocks and deposits. Knowing the source of water to Cave Springs is important in evaluating its potential for depletion caused by ground-water pumping as well as to protect the supply from contamination.

Cave Springs consist of several small springs that discharge from alluvial and glacial deposits near the contact between quartzite and granite. The four largest springs are diverted into a water-collection system. Water from the collection system at Cave Springs had more dissolved strontium, calcium, and bicarbonate, and was heavier in the stable isotope of carbon-13, which is denoted as delta carbon-13 or δ¹³C, than water from the spring at the contact between quartzite and granite near Baker Creek campground indicating that water at Cave Springs had dissolved limestone prior to discharging. The source of the limestone at Cave Springs was determined to be rounded gravels from a pit near Baker, Nevada, which was placed around the springs during the reconstruction of the water-collection system in 1996. A water sample from Cave Springs collected July 1987 had similar dissolved concentrations of calcium, magnesium, and bicarbonate as the water sampled in September 2007 from Marmot Spring indicating a similar source prior to reconstruction of the water-collection system. A geochemical model using the water chemistry prior to reconstruction resulted in a plausible reaction model involving the dissolution of calcite and dolomite to produce the water chemistry at Cave Springs in September 2007.

Stable isotopes of hydrogen (δD) and oxygen (δ¹⁸O) were lightest (most negative values) at Cave Springs and Marmot Spring and heaviest (least negative values) at a permanent pool in Lehman Caves. Comparison of stable isotopes in water at Cave Springs with winter and summer precipitation indicates that the source of water is primarily from winter precipitation. Mixing of water at Cave Springs from alluvial and glacial deposits along Lehman Creek with water from quartzite as represented by Marmot Spring is unlikely because δD and δ¹⁸O values from the spring near upper Lehman Creek campground is heavier than those at Cave Springs and Marmot Spring. Additionally, the estimated mean age of water from dissolved chlorofluorocarbon concentrations indicates water discharging from the alluvial and glacial deposits is younger than that discharging from either Cave Springs or Marmot Spring.

Because Cave Springs discharges from alluvial and glacial deposits at the upstream side of the contact between quartzite and granite, the potential for spring depletion from ground-water pumping in Snake Valley is less than if carbonate rocks were present beneath the springs providing a better connection with alluvial aquifers in the valley. Finally, the present protective fence enclosure around Cave Springs is sufficient because most of the source area to the springs is from the steep eastern slope of Jeff Davis Peak and not from alluvial and glacial deposits west of the springs.