Watching Groundwater in the Death Valley Region: USGS Monitoring Networks

By Steven R. Reiner, Peggy E. Elliott, Katherine J. Earp and Wayne R. Belcher. USGS Fact Sheet 2020–3018, March 2020, prepared with the U.S. Department of Energy, the Bureau of Land Management, the U.S. Fish and Wildlife Service, the National Park Service, and Nye and Inyo Counties.

The Funeral Range. Photo: Wayne R. Belcher, USGS.

Water is scarce in the arid Southwest. In the Death Valley regional groundwater flow system (DVRFS), in southern Nevada and eastern California, groundwater is the main supply for farms, businesses and homes. For more than four decades, the USGS Nevada Water Science Center has collected hydrologic data here for local (Nye County, Nev., and Inyo County, Calif.) and federal partners.

The region

The DVRFS covers about 80,000 square kilometers:

• Amargosa Desert: between Death Valley National Park (southwest) and the Nevada National Security Site (northeast), south of Yucca Mountain; it includes Amargosa Valley, Ash Meadows National Wildlife Refuge and Devils Hole, a detached unit of the national park.
• Nevada National Security Site (NNSS): where the U.S. tested more than 900 nuclear devices, atmospheric and underground, from the 1950s to the early 1990s.
• Yucca Mountain: the proposed national repository for high-level nuclear waste and spent nuclear fuel.

The monitoring networks and their sites. Map: USGS.

Why monitor

The data show how water-dependent natural and economic resources could be affected, and help managers decide. The USGS measures depth to water, groundwater withdrawals, spring discharge and water temperature. The records have been used to assess:

• water levels and spring flows before development;
• variability and trends in groundwater levels;
• the direction of regional flow and how geologic structures steer it;
• hydraulic gradients, horizontal and vertical;
• the effects of widespread pumping on managed resources;
• links between wells and areas of recharge or pumping;
• the accuracy of regional groundwater models.

Three networks

The USGS measures water levels, water use, spring discharge and temperatures (including temperature profiles down some wells), monthly to annually.

The Amargosa network's history: from 1992 through March 2009, water levels and spring flows here were measured monthly for the Yucca Mountain Project's environmental monitoring — 35 wells, 6 springs and Devils Hole. When the project was defunded in 2009, the network shut down. In 2010, Interior agencies (BLM, NPS, FWS and USGS) and Nye and Inyo counties revived a modified version: the Amargosa Integrated Network.

How the data are collected

Measuring water level with a steel tape (A, Oasis Valley) and an electric tape (B, Crater Flat), and spring discharge with a velocity meter (C). USGS photos.

• Water levels: steel tapes for water less than 100 feet down; electric tapes from 100 to more than 4,000 feet.
• Calibration: where water is more than 1,000 feet deep, tapes can stretch under their own weight, so the center has calibrated them every year in-house since 1999, against a NIST-certified steel reference tape.
• Springs: flow is measured by velocity meter, flume or a container of known size, depending on the spring.
• Quality: all data follow established protocols and are quality-assured before going into public databases.

What long records reveal

Records of more than 20 years show what drives seasonal, yearly and decade-long change.

Hydrographs from four sites. Graphs: USGS.

• Devils Hole: a water-filled fracture, home of the endangered Devils Hole pupfish. Its record caught water levels falling in the 1960s and early 1970s from nearby pumping, then recovering after pumping stopped — baseline data for federal and Nevada decisions to protect the fish.
• Recharge from wet winters: wells near Yucca Mountain rose after the winters of 1995, 1998, 2000, 2001, 2005 and 2010, with most trending upward from 2000 to 2015.
• Beatty Wash Terrace Well: seasonal swings from plant water use (evapotranspiration) and recharge events such as 1998, on top of a longer decline, probably from nearby pumping.
• ER-20-4 deep: steady water levels deep beneath Pahute Mesa, except a sharp drop in 2015 when the well was pumped for nearby construction.
• Crystal Pool: this Ash Meadows spring has flowed at a steady 5 to 7 cubic feet per second (12,000–17,000 cubic meters a day) for more than 20 years, a sign it is fed by the regional carbonate aquifer from distant recharge, not by local conditions.

A spring at Ash Meadows. Photo: Claudia C. Faunt, USGS.

Getting the data

All quality-assured data are in the USGS National Water Information System: waterdata.usgs.gov/nv/nwis. Data for the NNSS networks are on the USGS–Department of Energy Cooperative Studies in Nevada site.

Sources

Based on Hydrologic Monitoring Networks in the Death Valley Regional Flow System, Nye County, Nevada and Inyo County, California, by Steven R. Reiner, Peggy E. Elliott, Katherine J. Earp and Wayne R. Belcher, USGS Fact Sheet 2020–3018, U.S. Geological Survey; a work of the United States government in the public domain. The map, photographs, network table and hydrographs are taken from the fact sheet's PDF.