Exploration for Reliable Groundwater in an Igneous-Mantled Regional Carbonate Aquifer, Death Valley National Park

In October 2015, a flash flood of historic proportions in Grapevine Canyon, in the northeast portion of Death Valley National Park, caused major damage to the Scotty’s Castle area including the historic spring-water catchment system used as the potable water supply for the area. To replace this system with a more reliable and flood-resistant water supply, it was determined that development of groundwater was feasible, but that successful well siting could be difficult given the ambiguity of subsurface conditions. Grapevine Canyon is a largely east-west trending drainage in the northern part of the Amargosa Range, draining west into Death Valley. Quaternary alluvium and Tertiary intrusive and volcanic rocks fill Grapevine Canyon and overlie a Paleozoic regional carbonate aquifer system that was the target for groundwater development. The second-largest spring discharge complex in the National Park discharges from this aquifer to the northwest of the study area. Utilizing Controlled-source Audio-frequency Magnetotellurics (CSAMT) techniques, a geophysical survey of Grapevine Canyon was conducted to quantify the depth of the overburden above the carbonate aquifer, the depth to presumed production groundwater levels, and the location of candidate penetrative fractures that could enhance local transmissivity. Linear transects along the axis of Grapevine Canyon were coupled with shorter north-south survey lines to provide three-dimensional representations of the canyon and surrounding uplands. Not only were the results of the geophysical survey used to site the location of a test well, but provided information on the nature of the regional aquifer in this part of the National Park.