REGIONAL WATER TABLE (2014) IN THE MOJAVE RIVER AND MORONGO GROUNDWATER BASINS, SOUTHWESTERN MOJAVE DESERT, CALIFORNIA by Nick F. Teague, Christina L. Stamos, Sally F. House, and Dennis A. Clark
Data for static water-levels measured in about 610 wells during March-April 2014 by the U.S. Geological Survey (USGS), the Mojave Water Agency (MWA), and other local water districts were compiled to construct a regional water-table map. This map shows the elevation of the water table and general direction of groundwater movement in and around the Mojave River and Morongo groundwater basins. Water-level measurements recorded by the USGS and MWA staff were measured and compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey (Cunningham and Schalk, 2011). Water-level data submitted by cooperating local water districts were collected by using procedures established by the corresponding agency, and compiled according to the procedures described in the Groundwater Technical Procedures of the U.S. Geological Survey (Cunningham and Schalk, 2011). All data were compared to historical data for quality-assurance purposes. Water-level contours from the 2012 water-level map (Teague and others, 2014) were used as a guide to interpret and shape the 2014 water-level contours in areas where 2014 water-level data were not available; these contours are shown as dashed (approximate) on the water-table map. In addition to being available on the interactive map, 2014 water-level data and contours are shown for the entire area of the Mojave River and Morongo groundwater basins on Plate 1. Water-level data for 2014 are accesible through the website by clicking the 2014 Sites button on the Data Downloads page.
Historical water-level data from the National Water Information System (NWIS) database were used in conjunction with data collected for this study to construct 37 water-level hydrographs to show long-term (1930-2014) and short-term (1990-2014) water-level changes in the Mojave River and Morongo groundwater basins. Water-level changes between the spring of 2012 and spring of 2014 were determined by comparing water levels measured in the same well during both periods. Water-level changes between any of the study years on this website can also be displayed on the interactive map by selecting the years of interest from the "Water-Level Changes between 2 Years" menu.
Long-term (1930–2014) water-level changes are depicted by 25 water-level hydrographs (shaded) for the Mojave River and the Morongo groundwater basins. Wells for three hydrographs (wells 5N/5W-22E6, 11N/4W-29R1, and 11N/4W-30N1) were destroyed or were unable to be measured in 2014, but are shown to provide information that is discussed in previous versions of this report.
Data from more than one well were combined in hydrographs to show water-level changes over long periods in particular subareas. Combining data from multiple wells onto a single hydrograph was done when a well went dry due to a decline in the water table, or could no longer be measured, and data from a well nearby could be used to continue the record. Data from the different wells are shown by using different colored data points on the hydrographs.
The Morongo groundwater basin is divided into 17 subbasins. All of the long-term hydrographs for the Morongo groundwater basin showed declines in water levels of variable magnitude since the wells were first measured. Water levels have declined
Twelve short-term hydrographs (unshaded) were constructed from data collected between 1990 and 2014 in the Mojave River groundwater basin. Most hydrographs show data from wells that are located along the Mojave River and record the effects of seasonal recharge and discharge along the river, artificial recharge, and evapotranspiration, which is minimal during winter months. These short-term hydrographs show that
Water-level changes between spring of 2012 and the spring of 2014 can be viewed by selecting those years on the water-level change map (water-level change maps can be created using the "Water-level Changes between 2 Years" menu). Water-level data exist for 479 wells in the Mojave River and Morongo groundwater basins for both years. In 2014
Of the 325 wells assessed within the Mojave River groundwater basin, water-level data shows
Overall, water levels in wells along the Mojave River in the Alto subarea and the Alto Transition zone have remained constant, because of the infiltration resulting from surface flow through the Lower Narrows (10261500) and the treated wastewater discharged by the VVWRA. Data from the Centro and Baja subareas showed that most wells had groundwater-level decreases. A small pumping depression (not shown on the map because of scale) created by efforts to pump and treat contaminated groundwater near Hinkley (11 miles northwest of Barstow), in the Centro subarea, likely decreases flow of groundwater from Hinkley to the north (Dennis Maslonkowski, CH2MHill, written commun., Jan 28, 2013). In the Baja subarea, most wells had water-level declines of between 0.5 and 5 ft. Several wells in the Baja subarea north of the Mojave River showed water-level increases. These increases likely are due to the effects of a reduction in pumpage in that area since 1994 (Mojave Water Agency Watermaster, 1995; Mojave Water Agency Watermaster, 2015).
Of the 154 wells compared within the Morongo groundwater basin,
In the Deadman, Mesquite, and Mainside subbasins, these water-level increases can be attributed either to fluctuations in pumpage or the effects from a possible reduction in pumpage (Li and Martin, 2011). The greatest water-level increases continue to be observed in the Warren subbasin, where artificial-recharge operations in Yucca Valley at artificial recharge sites and a reduction in groundwater pumpage (Stamos and others, 2013) have caused water levels to rise more than 250 ft (well 1N/5E-36K2) since 1994.
Teague, N.F., Stamos, C.L., House, S.F., and Clark, D.A., 2016, Regional water table (2014) in the Mojave River and Morongo groundwater basins, southwestern Mojave Desert, California, 2016: U.S. Geological Open-File Report 2016–1105, 1 sheet, scale 1:170,000, http://dx.doi.org/10.3133/ofr20161105.