SOURCES AND SINKS OF GROUND WATER AT HIGH DISCHARGE SPRINGS, DEATH VALLEY, CALIFORNIA

High flux springs in Death Valley are enigmatic considering their depleted d¹⁸O_VSMOW (-13 to -14‰) and dD_VSMOW (-102 to -112‰) values. To assess potential local recharge, we have conducted a synoptic sampling campaign in the eastern Death Valley area, including solute, stable isotope, and radiogenic isotope studies, in order to better understand the origin of discharge at these important resources. In addition to major springs in the Furnace Creek and Scotty’s Castle areas, mountain springs were monitored as potential surrogates for local recharge.

The high flux springs respond to climate variations in terms of discharge rate and isotopic composition. Hydrographs for Travertine and Nevares springs appear to correlate with climate. Variations in time-series stable isotope data track one another, indicative of a climate effect. This is striking because tracking occurs not only within groups of springs in a given area, but also between areas. For example, variations in d¹⁸O_VSMOW show a remarkably similar pattern between Nevares (Furnace Creek) and Staininger (Scotty’s Castle) springs, even though they are separated by ~80 km.

A critical question then becomes what percentage of discharge is supported by local recharge. Published estimates of discharge at Willow Spring (Black Mountains) result in estimates of discharge flux/km² of catchment area that, by analogy, could support much of the Furnace Creek discharge. Consistent with ¹⁴C ages (7500-11000 years), much of the water may have been recharged in the last pluvial period. Otherwise, isotopic measurements suggest that local recharge must be dominated by winter precipitation in order to produce the observed isotopic depletions.

Given these constraints, local recharge cannot be neglected in the description of the high flux springs in Death Valley. In the Furnace Creek system, we suggest that considerable storage may exist in older alluvium and near-surface fractured bedrock, and that this water is transferred to the Furnace Creek Fault zone, which controls the spatial distribution of discharge in the Furnace Creek area. This also permits the deep circulation (~1/2 km) required to heat the waters above mean annual air temperature.