Monitoring Hydrogeologic Conditions in the Regional Carbonate Aquifer, Clark County, Nevada

Science Center Objects

The USGS Nevada Water Science Center is evaluating and enhancing our current understanding of the hydrologic condition of the regional groundwater flow system in Clark County, Nevada. In order to achieve this objective, monitoring wells were installed in consolidated bedrock in six select regions throughout Clark County. Water-level, elevation, and borehole geophysical data were synthesized and used to develop a regional potentiometric map to improve the current understanding of regional groundwater flow within Clark County. Analyses of site specific information relating to flow across structural boundaries, groundwater and surface-water interactions, and chemical condition of waters from drilled wells were also conducted. This information will assist Federal resource managers in making informed decisions about maintaining and protecting groundwater resources within Clark County.

Groundwater from the deep regional consolidated rock aquifer in east-central Nevada is currently being explored as a potential water supply. Understanding the potential impact to the regional groundwater aquifer by development is limited due to lack of deep wells that help define the hydrogeology of this system. In order to further understand the hydrogeologic conditions in the regional carbonate aquifer in Clark County, and to better understand the connection between the carbonate aquifer and springs in the region, deep wells need to be installed in areas of critical concern.

BACKGROUND

The regional consolidated carbonate-rock aquifers in Southern Nevada are believed to yield up to 160,000 acre-ft/yr and effects from pumping on the regional water-level surface are not clearly understood. Few deep wells with water-levels representative of the regional water-level surface exist; therefore, a quantitative analysis of the regional groundwater potential is limited. Additionally, the lack of wells completed in regional carbonate-rock aquifer systems limit the general understanding of effects on pumping within localized hydrogeologic settings. For example, additional data on water level changes across individual fault lines, groundwater withdrawal effects on springs, and the general chemical condition of groundwater would increase understanding of local conditions in the regional carbonate aquifer. Further evaluations of the direction of groundwater flow, in regional systems, provides valuable data that will enhance our understanding of water-balances in aquifer systems that are potentially impacted by pumping; sustain biologically-sensitive aquatic, riparian, and phreatophytic ecosystems; and discharge at springs, river drainages, and playa areas.

WELL SITES

To evaluate the hydrologic condition of the regional carbonate-aquifer system in Clark County, wells were installed in consolidated bedrock in six select regions throughout Clark County. Data from these six regions will be integrated at a regional scale to
examine the condition of the carbonate-rock aquifer. Well sites were selected to examine scientific questions related to

  • interbasin flow,
  • groundwater flow paths,
  • source waters, and
  • susceptibility to potential pumping.

Sites were located in areas where additional monitoring wells add to the understanding of the regional groundwater flow systems. At each site:

  • Surface geophysical surveys were conducted to identify depth to carbonate rock.
  • Permits and compliance applications were completed for each drill site.
  • Bore holes were drilled into consolidated carbonate rock.
  • Borehole geophysical logs and cutting samples were collected.
  • Geophysical logs and cuttings were analyzed to identify detailed lithology.
  • Wells were completed as monitoring wells to provide for long-term monitoring of groundwater.
  • Water levels and water chemistry were collected and evaluated to identify the potentiometric surface and hydrochemical condition of groundwater at each location.

DATA

Available data for each well is available from the links below. NWISweb is the web interface for the USGS National Water Information System (NWIS). USGS Groundwater Watch is built on the data available from NWISweb and presents statistics about the water-level data collected at each site. Groundwater watch links are available for sites that have data being collected currently.

  • USGS 364204114454501 219 S14 E65 19CBDB1 BW-01: NWISweb 
  • USGS 362454115270201 212 S18 E58 02BDC 1 LSC-01: NWISweb 
  • USGS 362135114285401 215 S18 E67 22AABC1 RB-01: NWISweb
  • USGS 362352114414501 218 S18 E65 11DBBC1 BUFPKTS-01: NWISweb || Groundwater Watch
  • USGS 354849115225001 164A S24 E59 32DACD1 IVPH-01: NWISweb 
  • USGS 362901115220001 212 S17 E59 16AAAB1 JM-01: NWISweb 
Drilling a well in the carbonate-rock aquifer near Lake Mead, Clark County, Nevada
Drilling a well in the carbonate-rock aquifer near Lake Mead, Clark County, Nevada (Public domain).