Mojave Groundwater Resources

Water-Level, Water-Quality and Land-Subsidence Studies in the Mojave River and Morongo Groundwater Basins

Scientific Investigations Reports 2007-5097 and 2011-5234

Welcome to the U.S. Geological Survey (USGS) California Water Science Center's interactive web site for the Mojave River and Morongo groundwater basins. This site was created in order to centralize hydrologic data collected and compiled by the USGS for these basins and to allow readers to access available data and related reports online from the USGS. The interactive data map on this site allows the user to define and change the extent of the map of the basins, and to view the associated data with direct links to the USGS National Water Information System (NWIS) databases. The interactive map also offers tools for performing tasks such as querying data and identifying features shown on the map.

Starting in 2023, the Mojave River and Morongo groundwater basins defined in previous U.S. Geological Survey publications will be redefined as the Mojave River and Morongo areas, respectively, in new U.S. Geological Survey publications.

Sunset in the Mojave Desert

Sunset over the Mojave Desert

Since 1992, the U.S. Geological Survey (USGS), in cooperation with the Mojave Water Agency (MWA), has constructed a series of regional water-table maps for intermittent years in a continuing effort to monitor groundwater conditions in the Mojave River and Morongo groundwater basins. The previously published data, which were used to construct these maps, can be accessed on the interactive map. The associated reports describing the groundwater conditions for the Mojave River groundwater basin for 1992 (Stamos and Predmore, 1995), the Morongo groundwater basin for 1994 (Trayler and Koczot, 1995), and for both groundwater basins for 1996 (Mendez and Christensen, 1997), for 1998 (Smith and Pimentel, 2000), for 2000 (Smith, 2002), for 2002 (Smith and others, 2004), for 2004 (Stamos and others, 2004), for 2006 (Stamos and others, 2007), for 2008 (Stamos and others, 2009), for 2010 (Smith and others, 2011), and for 2012 (Teague and others, 2013), for 2014 (Teague and others, 2016), for 2016 (Dick and Kjos, 2017), for 2018 (Dick and Seymour, 2023), and for 2020 (Seymour and Dick, 2023) can be accessed via the Water-Level Studies page.

Water quality of the Mojave River and Morongo groundwater basins has been monitored by the USGS in cooperation with MWA and preceding agencies since the late 1900s. Various studies (Christensen and Fields-Garland, 2001; Ball and Izbicki, 2004; Izbicki and others, 2008; Mathany and Belitz, 2009; Wright and Belitz, 2010; Dawson and Belitz, 2012; and Izbicki and others, 2012) have noted elevated concentrations of several trace elements, nitrate, and total dissolved solids in groundwater in portions of the two basins. However, detailed analysis of the spatial distribution of inorganic water quality has not been updated since the 1990s (Christensen and Fields-Garland, 2001). An updated assessment of new results from ongoing MWA/USGS groundwater quality monitoring data collected annually for 2000 through 2012 from a network of wells, in combination with data collected during this period as part of the California Groundwater Ambient Monitoring and Assessment (GAMA) program, can be accessed via the Water Quality page.

Example image of InSAR in the Mojave area.

An example of an InSAR image in the Mojave area.

Spatially detailed maps of interferometric synthetic aperture radar (InSAR) were used to characterize land subsidence associated with groundwater-level declines during various intervals of time between 1992 and 1999 in the Mojave River and Morongo groundwater basins (Sneed and others, 2003). Concerns related to the potential for new or renewed land subsidence in the basins resulted in a cooperative study between the MWA and the USGS in 2006. InSAR data were developed to determine the location, extent, and magnitude of vertical land-surface changes in the Mojave River and Morongo groundwater basins for time intervals ranging from about 35 days to 14 months between 1999 and 2000 and between 2003 and 2004. The results from many future land-subsidence studies, which are scheduled about every 10 years, will be available on this website.

Mapping of water-level contours, water-level change, water-quality measurements and numerous interferometric synthetic aperture radar (InSAR) images were combined in an interactive map. This interactive map may be customized to your needs and viewed at a scale that is appropriate for the data.

Description of Study Area

The Mojave River and Morongo groundwater basins are in the southwestern part of the Mojave Desert in southern California, approximately 80 miles north and 40 miles northeast, respectively, of Los Angeles. The Mojave River and Morongo groundwater basins together encompass about 2,400 square miles. The climate of these basins is typical of the Mojave Desert region of southern California. Most areas of the basin floor receive 4 to 6 inches of precipitation per year, although annual precipitation can be greater than 40 inches in the southern and eastern San Bernardino and the San Gabriel Mountains (Lines, 1996). Recharge to the groundwater system from direct infiltration of precipitation is minimal.

Surface water in these basins is minimal and normally is limited to ephemeral flow during winter and spring storms and discharge from perennial springs in some areas of the Morongo groundwater basin. The major source of surface water is the Mojave River; however, its flow is unpredictable and not a dependable source for water supply because most of the river’s 100-mile channel usually is dry. The lack of significant surface-water resources has resulted in the use of groundwater as the primary source for private, agricultural, and municipal supply. Because of increasing urbanization, demands on local water supplies have created overdraft conditions in some areas of the desert basins. Significantly lowered water levels have the potential to induce or renew land subsidence in the Mojave River and Morongo groundwater basins. Land subsidence can result in the disruption of surface drainage, reduction of aquifer-system storage capacity, formation of earth fissures, and damage to wells, buildings, roads, and utility infrastructure.

Mojave River Groundwater Basin (Mojave River area)

The Mojave River groundwater basin is approximately 1,400 square miles and extends from the San Bernardino and the San Gabriel Mountains in the south to north of Harper and Coyote Lakes (dry). The groundwater basin is bordered on the west by Antelope Valley and shares its southeastern boundary with the Morongo groundwater basin. For water-management purposes, the Mojave River groundwater basin was divided into five subareas, partially based on the Mojave River drainage basin boundary:  Baja, Centro, Alto, Este, Oeste

The primary source of groundwater recharge in the Mojave River groundwater basin is intermittent streamflow in the Mojave River, which usually occurs during January through March, and from sporadic releases of imported water from the California State Water Project (SWP). The basin has received SWP water at the Rock Springs recharge site (near well 4N/3W-29E5) southeast of Hesperia since 1994, and has also received SWP water at the Hodge recharge site (near well 9N/3W-23D2) since 1999, at the Lenwood recharge site (near well 9N/3W-1R7) since 1999, at the Yermo/Daggett recharge site (near well 9N/1E-20B3) since 2003, and at the Newberry Springs recharge site (near well 9N/3E-22R7) since March 2006 (Brian Hammer, Mojave Water Agency, written commun., 2006).

Morongo Groundwater Basin (Morongo area)

The Morongo groundwater basin is about 1,000 square miles and is surrounded by the Ord and Granite Mountains to the north, the Bullion Mountains to the east, the San Bernardino Mountains to the southwest, and the Little San Bernardino Mountains to the south. The Morongo groundwater basin is separated into 17 subbasins: Lucerne, Fry, Johnson, Upper Johnson, Means, Pipes, Reche, Emerson, Giant Rock, Copper Mountain, Surprise Spring, Deadman, Mesquite, Mainside, Warren, Joshua Tree, and Twentynine Palms. The Morongo groundwater basin is recharged by infiltration from flow in ephemeral stream channels and, since 1995, from SWP water recharged to ponds at three Hi-Desert recharge sites (near wells 1N/5E-36M5 and 1N/5E-34Q1) in the Warren subbasin.


Joshua Tree

Joshua tree, commonly found in the Mojave Desert.

The boundaries of the Mojave River and the Morongo groundwater basins generally are defined by the contact between the water-bearing unconsolidated deposits and the surrounding and underlying non-water-bearing consolidated igneous and metamorphic rocks. The groundwater system in the Mojave River Basin consists of two interconnected unconfined aquifers—a floodplain aquifer and an underlying and surrounding regional aquifer, which are part of the Basin and Range aquifers in southern California. The most productive aquifer is the floodplain aquifer, which is composed of permeable young river deposits of Holocene age and older river deposits of Pleistocene age. This aquifer is as much as 200 ft thick and yields most of the groundwater pumped from the Mojave River Basin (Stamos and others, 2001). The most widespread aquifer in the area is the regional aquifer; it is composed of unconsolidated older alluvium and fan deposits of Pleistocene to Tertiary age. In some places, the regional aquifer also consists of partly consolidated to consolidated sedimentary deposits of Tertiary age. The regional aquifer is as much as 1,000 ft thick. Other geologic units, such as bedrock and lake deposits, commonly contain groundwater, but they are not considered reliable sources of ground water in the study area.

The Mojave River and Morongo groundwater basins are separated by the Helendale Fault, which acts as a barrier to groundwater flow near Lucerne Valley. The regional aquifer in the Morongo groundwater basin consists of continental deposits of Quaternary and Tertiary age that extend to as much as 10,000 ft deep (Moyle, 1984). For a more comprehensive description of the geohydrology of the groundwater basins, the reader is referred to Stamos and others (2001).

Perched groundwater has been identified in four areas of the Mojave River and Morongo groundwater basins. Perched groundwater is unconfined ground water separated from an underlying body of groundwater by an unsaturated zone (Lohman, 1972). The approximate areas of perched groundwater in the Mojave River groundwater basin are near El Mirage Lake (dry) and northeast of the city of Adelanto, and in the Morongo groundwater basin are Lucerne Valley and Mesquite Lake (dry) (Mendez and Christensen, 1997)