Use of major ion chemistry and environmental isotopes to delineate subsurface flow in Eagle Valley, Nevada

Abstract

Snow sampling in the main recharge mountains of Eagle Valley indicates non-equilibrium fractionation of stable isotopes from: 6D/H = 6.0 ( 618o/160)-14 . There is significant correlation of isotopic depletion with elevation indicated by: 6 D/H = -9.9W1000 ft and 618/16 = -1.48V1000 ft. Electrical conductivity and chloride enrichment from snow to lysimetric water produces 4000 acre-ft/year of potential recharge from the Carson Range. Monitoring of lysimeters throughout the winter shows that ground is not frozen under snow. Contour maps of sulfate, chloride, sodium, carbon-13, and deuterium concentrations in the valley aquifer suggest thermal/non-thermal water mixing. Aquifer stable isotope values and recharge area values indicate recharge to the aquifer via stream channel infiltration and deep percolation. Tritium and carbon-14 dating of non-thermal water in the aquifer shows recharge from the Carson Range and near the Carson River, and the oldest non-thermal water in the basin center. Carson Hot Springs is about 12,500 years old and is isotopically depleted, whereas Prison Hot Springs contains recent water and is not depleted.