Evaluation of water resources in Chuckwalla Valley, Riverside County, California

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The Chuckwalla Valley in the southern Mojave Desert in California has been selected as an area with high potential for solar energy development. Six large-scale solar energy projects are currently approved or proposed in this basin, the largest number of solar projects in any one basin in California. Water needs associated with proposed solar energy projects within the basin have generated concerns over potential impacts to local groundwater resources and phreatophytic vegetation habitats.

Image of the Chuckwalla Valley, California (Photo by Chris Clarke, © 2011).

Image of the Chuckwalla Valley, California.

(Credit: Chris Clarke. Photo courtesy of Chris Clarke, copyright 2011)

The Bureau of Land Management (BLM) and DOE's Lawrence Berkeley National Laboratories (LBNL) have proposed a two-phase research study to develop a groundwater budget for the Chuckwalla Valley and evaluate the impacts of alternative energy development in groundwater resources in the valley. Phase 1 of the study involves collecting data on the geohydrologic framework of the Chuckwalla Valley groundwater basin, with emphasis on collecting data on the quantity of groundwater underflow through the eastern outlet from the basin. Phase 2 of the study will involve developing a numeric model of water flux through the basin and the resulting water balance. Few data are currently available near the eastern outlet of the basin to define the subsurface geometry of the basin outlet and the quantity and quality of groundwater underflow.

To meet the objectives of Phase 1, in part, the USGS has proposed to construct a monitoring site to improve the understanding of the aquifer system, water levels, water quality, and groundwater flow near the eastern outlet of the Chuckwalla Valley. The monitoring site will provide information on the (1) depth to bedrock, (2) lithology of the basin-fill deposits, (3) aquifer properties, (4) water levels and hydraulic gradient, and (5) water quality near the eastern outlet of the basin.

The study will develop a greater understanding of the lithology, geologic structure, and hydrologic conditions of the eastern part of the Chuckwalla Valley. Data collected from this study will be used by BLM and LBNL to evaluate the water budget of the entire Chuckwalla Valley and help BLM assess the feasibility and potential impacts of alternative energy development in the valley. BLM anticipates that the USGS will be requested to assist LBNL on future tasks of this larger study, but at this time the scope and funding for the larger study have not been defined and is limited to Phase 1. The proposed study addresses USGS strategic science Directions "A Water Census of the United States," and provides information directly relevant to the water/energy nexus.

A monitoring site consisting of 1-3 monitoring wells in a single borehole will be constructed to determine the depth, lithology, and water-bearing properties of the basin-fill deposits near the eastern outlet of the Chuckwalla groundwater basin. After the monitoring well has been properly developed, a single-well aquifer test will be completed to estimate the aquifer transmissivity. Water levels will be measured in the well(s), and water-quality samples will be collected and analyzed. All appropriate data will be entered into the USGS National Water Information System (NWIS). An Open-File report will be prepared documenting the results of the study.