Nevada Water Science Center

Groundwater Discharge and Water Quality in Dixie Valley

Recent proposals for new groundwater appropriations in Dixie Valley, NV have prompted concern for the availability, quality, and sustainability of the water resource.  Although previous studies estimated groundwater discharge of the flow system, recent advancements in evapotranspiration estimation warrant a reevaluation of previous estimates. An updated groundwater discharge estimate for Dixie Valley coupled with a better understanding of the spatial variability in groundwater flow, geochemistry, and geothermal waters will provide Churchill County water planners with the information necessary to evaluate the proposed inter-basin transfer.

Research Plan

The hydrogeology of the Dixie Valley flow system will be characterized by: 

  • Developing a hydrogeologic framework from geologic and geophysical data.
  • Characterizing water quality of the basin-fill aquifer using existing data and periodic measurement of major constituents in groundwater and springs within the Dixie Valley HA.
  • Evaluating ground-water flow using ground-water levels, subsurface inflow estimates, and water-quality data.
  • Estimating groundwater discharge for the Dixie Valley flow system using groundwater ET by phreatophytes and evaporation from playas, spring and seep flow measurements, and groundwater withdrawals.

Background

Quantification of water resources is essential in the arid southwest where demand for water is increasing with increasing populations. One of the driest states in the U.S., Nevada has increased in population by nearly 30 percent over the last eight years (2000–2007; U.S. Census Bureau), the majority of which has occurred in urban areas.  Finite water resources in urban areas have thus led to the initiation of large scale water importation projects, which commonly incur applications for additional, new appropriations.  In order to sustain continued growth in the Fallon urban area of the Carson Desert, Churchill County water planners are seeking additional water resources. The Dixie Valley HA, a primarily undeveloped basin neighboring the Carson Desert to the east, is currently a candidate for groundwater exportation into the Carson Desert (public Law 110-161). 

The Dixie Valley flow system is comprised of the Dixie Valley HA and six hydraulically connected basins:  pleasant Valley, Jersey Valley, Fairview Valley, Stingaree Valley, Cowkick Valley and Eastgate Valley (Harrill and Hines, 1995). Dixie Valley, which serves as the terminus of the flow system, is bordered on the west and northwest by the Stillwater Range, on the east and southeast by the Clan Alpine Mountains, on the south by Fairview Valley and on the north by the Tobin Range.  Similar to most basin and range valleys in Nevada, erosion of surrounding mountains has filled Dixie Valley with unconsolidated deposits that constitute the basin-fill aquifer system.  Although tertiary volcanic material may exist beneath and within (interbedded) older basin fill deposits, most if not all groundwater pumping is from the basin-fill aquifer system.  Due to interbedded layers of fairly permeable sand and gravel with comparatively impermeable silt and clay, groundwater in Dixie Valley basin-fill aquifer system is under both unconfined and confined conditions. 

Dixie, Jersey, and pleasant Valleys have numerous thermal springs and wells. Documented temperatures range from 64 to 175 degrees Fahrenheit. The Dixie Valley power plant, located in central Dixie Valley is the largest producer of geothermal energy in the state of Nevada. On average from 2004 to 2007, about 19,100 acre-feet of groundwater were pumped with an average water temperature of about 332 degrees Fahrenheit. Approximately 510 megawatt hours of energy were produced and about 14,500 acre-feet of groundwater were re-injected (State of Nevada Commission on Mineral Resources, written commun., 2008,).  Flowing artesian wells are also common in the Dixie Valley flow system, some discharging at rates as high as 200 gallons per minute (Cohen and Everett, 1963). 

Groundwater discharge occurs primarily by ET from vegetated areas comprised of desert phreatophytes, drought deciduous shrubs, and crops, and evaporation from playas and bare soil.  Reconnaissance groundwater discharge estimates for the Dixie Valley HA range from 16,000 to 28,000 acre-ft/yr (Cohen and Everett, 1963; Harrill and Hines, 1995). Despite previous estimates, recent advancements in ET estimation and remote sensing techniques warrant a reevaluation of the groundwater discharge. An updated groundwater discharge estimate for Dixie Valley and a better understanding of the spatial variability in groundwater flow, geochemistry, and geothermal waters will provide Churchill County with the information necessary to evaluate the proposed inter-basin transfer.

USGS scientist servicing ET equipment in Dixie Valley

Quick Facts

 

Location: Dixie Valley, Churchill County, western Nevada

Start Date: 2009

End Date: 2013

Cooperator: Bureau of Reclamation

Contact Information

 

Amanda Garcia

USGS Nevada Water Science Center

2730 N. Deer Run Rd.

Carson City, NV 89701

phone: (775) 887-7684

Email: cgarcia@usgs.gov

 

Jena Huntington

USGS Nevada Water Science Center

2730 N. Deer Run Rd.

Carson City, NV 89701

phone: (775) 887-7692

Email: jmhunt@usgs.gov

 

Abbreviations

 

acre-ft/yr: acre-feet per year

ET: Evapotranspiration

HA: Hydrographic Area

 

 

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page Last Modified: May 2, 2012