Environmental isotope investigation of groundwater flow in the Honey Lake Basin, California and Nevada

Abstract

DISCLAIMERThis document waa prepared aaan account of work aponaoredby an agency oftha United StataeGovernment. Neither the United States Govemmmt nor the University dCatifomia nor any oftbeir employeeajmakea any wammty, express or bnpiied, or assumes any legal liability or reapodbiiity for the accuracy, completenõ r uaefulnem of any information, apparatus produ~or procasadwloa@ or repreaentathat itaueewould not infringe privately owned rights. Reference herein to any apeeif&commerdal productvjproc~or service by trade name trademark, manufacturer, or otherw@ doeanot necaswi iy COldtUteOf imply k? endoraemen b recommmdatkq or favoring by the United StatesGovernment ortbeUnkraity ofCalifomia. Theviews and opinions of authora mpreaaed herein do not necessarily state or reflect thoee of the United StatesGovernment or theUniversity ofCaiiiomi~and ahatl not be used for advertising or product endorsement purpoaea.Thii report baa been reproduced directly from the best available copy. . Isotopic and chemical data are consistent with groundwater discharge within an evapotranspiration zone along the central axis of the basin. Evidence inclu&s: (1) relatively old 14Cages at shallow depths; (2) moderately evaporated 51*0-5D signatures in shallow groundwaters from this arew and (3) correspondingly high electrical conductivities in the evaporated groundwaters. considerably less than the estimate of 130,000 ac-ft yr-l given by Handman et al. (1990). It should be emphasized that recharge is not uniform across the basin. The highest recharge rates occur in the western part of the basin, where precipitation rates are the greatest.Estimated recharge rates along the base of the Sierra Nevada range are on the order of 17,000 to 23,000 ac-ft yr-l." The effect of intensive groundwater pumping in the eastern half of the basin would be equivalent to groundwater "mining" since the majority of the groundwater in this region has old 14Cages. Moreover, prolonged pumping would be expected to induce the migration of contaminants that currently reside in shallow groundwater within the boundaries of the Sierra Army Depot. {2 IntroductionHoney Lake Basin is a 5700 km2 closed alluvial basin located in the semi-arid high desert -100 km northwest of Reno, Nevada. The proposed development of production wells to augment the municipal water supply for Reno provided the impetus for several recent studies aimed at understanding the hydrogeology and availability of water resources in the basin (e.g. Handman et al., 199~Rockwell, 199Q Bohm, 199Q Stone et al., 1990).Two central issues must be addressed with regard to water resource development in this region. First, the rate at which the aquifer is recharged must be evaluated in order to determine how much groundwater withdrawal the basin can sustain before serious overdmfting occurs. Second, there is a question as to whether intensive groundwater pumping will induce the migration of contaminants residing in shallow groundwaters beneath the Sierra Army Depot, on the eastern side of Honey Lake (see Figure 1)...

Hydrologic resources management program and underground test area operable unit fy 1997

“…However, this model is most compatible with closed-basin systems wherein groundwater recharge from pluvial periods is stored as a static mass that remains poorly mixed with modern recharge (e.g. Rose et al, 1997a). Groundwater flow beneath Pahute Mesa is considered to be a part of the Death Valley regional flow system, receiving recharge from the north in the Kawich and Reveille Ranges (see Figure 2; .…”