Welcome to the U.S. Geological Survey (USGS) California Water Science Center’s interactive web site for the Mojave River and Morongo ground-water 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 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.

Water-Level and Land-Subsidence Studies in the Mojave River and Morongo Ground-Water Basins

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 ground-water conditions in the Mojave River and Morongo ground-water basins. The previously published data, which were used to construct these maps, can be accessed on the interactive map. The associated reports describing the ground-water conditions for the Mojave River ground-water basin for 1992 (Stamos and Predmore, 1995); the Morongo ground-water basin for 1994 (Trayler and Koczot, 1995); and for both ground-water basins for 1996 (Mendez and Christensen, 1997); for 1998 (Smith and Pimentel, 2000); for 2000 (Smith, 2002); for 2002 (Smith and others, 2004); and for 2004 (Stamos and others, 2004) can be accessed using this web site. The latest water-level map in this series and the discussion of the ground-water conditions for the spring of 2006 in the Mojave River and Morongo ground-water basins are also now available on this website (2006).

Concerns related to the potential for new or renewed land subsidence in the Mojave River and Morongo ground-water basins resulted in a cooperative study between the MWA and the U.S. Geological Survey (USGS). Spatially detailed maps of interferometric synthetic aperture radar (InSAR) data were developed to determine the location, extent, and magnitude of vertical land-surface changes in the Mojave River and Morongo ground-water basins for time intervals ranging from about 35 days to 14 months between 1999 and 2000 and between 2003 and 2004.

Mapping of water-level contours, water-level change 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 ground-water basins are in the southwestern part of the Mojave Desert in southern California, approximately 80 and 40 miles northeast, respectively, of Los Angeles (location map). The Mojave River and Morongo ground-water 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 ground-water 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 ground-water 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 ground water 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 ground-water 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 Ground-Water Basin

The Mojave River ground-water 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) (interactive map showing Mojave River ground-water basin). The ground-water basin is bordered on the west by Antelope Valley (location map) and shares its southeastern boundary with the Morongo ground-water basin. For water-management purposes, the Mojave River ground-water basin was divided into five subareas, partially based on the Mojave River drainage basin boundary: Oeste, Alto (including the Transition zone), Este, Centro, and Baja (Detailed location map).

The primary source of ground-water recharge in the Mojave River ground-water 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)(recharge sites map) since March 2006 (Brian Hammer, Mojave Water Agency, written commun., 2006).

Morongo Ground-Water Basin

The Morongo ground-water 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 (interactive map showing the Morongo ground-water basin). The Morongo ground-water 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 (location map). The Morongo ground-water 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 (recharge sites in the Warren subbasin).

Geohydrology

The boundaries of the Mojave River and the Morongo ground-water 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 ground-water 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 ground water 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 ground water, but they are not considered reliable sources of ground water in the study area.

The Mojave River and Morongo ground-water basins are separated by the Helendale Fault, which acts as a barrier to ground-water flow near Lucerne Valley (ground-water levels on interactive map). The regional aquifer in the Morongo ground-water 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 ground-water basins, the reader is referred to Stamos and others (2001).

Perched ground water has been identified in four areas of the Mojave River and Morongo ground-water basins. Perched ground water is unconfined ground water separated from an underlying body of ground water by an unsaturated zone (Lohman, 1972). The approximate areas of perched ground water in the Mojave River ground-water basin are near El Mirage Lake (dry) and northeast of the city of Adelanto, and in the Morongo ground-water basin are Lucerne Valley (Jill Densmore, U.S. Geological Survey, written commun., 1999) and Mesquite Lake (dry) (Mendez and Christensen, 1997) (white stippled areas on interactive map ).