This study includes the Mojave River and Morongo groundwater basins.

Water-table contours and wells used in determining water-table altitudes (Selected years from 1992 to 2016): Contours show altitudes of water table. Contour intervals, in feet, vary. Dashed where approximately located, queried where uncertain. Hachures indicate depression. Datum is North American Datum of 1988 (NAVD88).

Download well/contour data.

Well Numbering System

Perched groundwater has been identified in four areas of the Mojave River and Morongo groundwater basins. Perched groundwater is unconfined groundwater separated from an underlying body of groundwater by an unsaturated zone (Lohman, 1972).

As part of a groundwater observation network, the Mojave Water Agency has constructed several Westbay multiple-level monitoring sites. These sites consist of an observation well and or instruments completed at different depths within a single borehole. Water-level data from the shallowest well of a Westbay Well site were used for the regional water-table maps. (SWS Technology).

As part of a groundwater observation network, the USGS, in cooperation with local water agencies, water districts, the military, and private landowners, has constructed many multiple-well monitoring sites. These sites consist of a cluster of two or more observation wells completed at different depths within a single borehole, each typically screened across a 20-foot interval (Huff and others, 2002). Data from the shallowest well of a multiple-well site were used for the regional water-table maps.

Hydrographs show long-term or short-term water-level changes in a well through time.

Artificial recharge is the process of forcing clean water back into a ground-water aquifer. Artificial recharge began in the Yucca Valley area in 1995 and has reversed the trend of declining water levels in the Warren subbasin.

Stream gaging stations are located at:

• Deep Creek, near Hesperia (10260500)
• West Fork Mojave River, near Hesperia (10260950)
• Mojave River at The Forks (Deep Creek and West Fork)
• Mojave River Lower Narrows, near Victorville (10261500)
• Mojave River at Barstow (10262500)
• Mojave River at Afton (10263000)

From National Oceanic and Atmospheric Administration and linked to NOAA website data.

This dataset shows the distribution and concentration of selected water-quality constituents using maps, cumulative distribution function (CDF) graphs and time-series graphs to show the distribution and concentration of selected water-quality constituents for 2000-12.

Contours of subsidence are lines of equal displacement interpreted from InSAR intrerferograms. This technique is useful for the visualization of the extent and magnitude of subsidence in an area. The contour interval, which is the difference in subsidence between successive contour lines, is 5 mm.

Viewing the contours of subsidence for selected InSAR images

1. Check the box next to the date of the desired subsidence contour in the "Contours of subsidence for selected InSAR images" column.
2. Select the InSAR image with the corresponding date in the "View InSAR images" box. Note: not all InSAR images have been contoured.
3. Click on the "Update Display" button and the display will zoom to the appropriate area(s).

Interferometric Synthetic Aperture Radar (InSAR) is an effective way to measure vertical changes of land surface. InSAR is a satellite-based remote sensing technique that can detect ground-surface displacement of about a third of an inch (centimeter) over an area approximately 60 x 60 mi (100 x 100 km) with spatial resolution on the order of about 300 ft (90 m) or less. This technique has been used to investigate deformation resulting from earthquakes (Massonnet and others, 1993), volcanoes (Massonnet and others, 1995), and land subsidence (Massonnet and others, 1997; Fielding and others, 1998; Galloway and others, 1999; Amelung and others, 1999, Hoffmann and others, 2001; Sneed and others, 2000).

This dataset illustrates the change between the selected first year's water-level altitude and the selected 2nd year's water-level altitude. These values have been categorized as represented in the Legend. Colors are ramped, in 9 categories, from violet to red; illustrating a rise of greater than 30 feet for the violet triangle, a change of less than or equal to 0.5 feet for the grey square, and a decline of greater than 30 feet for the red triangle.

Combined datasets from the following:

Cox, B.F., and Wilshire, H.G., 1993,

Geologic map of the area around the Nebo Annex, Marine Corps Logistics Base, Barstow, California: U.S. Geological Survey Open-File Report 93-568, 36 p., 1 map sheet, scale 1:12000

http://pubs.er.usgs.gov/usgspubs/ofr/ofr93568

California Division of Mines and Geology faults.

Fault location from Official Earthquake Fault Zone maps by California Division of Mines and Geology.

Water-table contours and wells used in determining water-table altitudes (Selected years from 1992 to 2016): Contours show altitudes of water table. Contour intervals, in feet, vary. Dashed where approximately located, queried where uncertain. Hachures indicate depression. Datum is North American Datum of 1988 (NAVD88).

Download well/contour data.