The U.S. Army Fort Irwin National Training Center (NTC), approximately 35 miles north-northeast of Barstow, California, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle Basins) within the NTC boundaries. In these basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, managed aquifer recharge using recycled water (treated wastewater) has offset water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (for example, wastewater disposal practices, landscape irrigation, and (or) leaking pipes). As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army, the U.S. Geological Survey (USGS) evaluated unsaturated zone soil property data of cores from a borehole for a newly drilled monitoring well near a dry well and irrigated Four-plex baseball field. Measurements and observations are presented for cores from an initial drilling attempt (site ESW2A), which stopped at 85 feet below land surface due to equipment issues, and data are presented for cores from the successful drilling attempt (ESW2B) down to 240 feet below land surface. The two boreholes are located approximately 6 feet from each other. The grain size measurements were compared to a reference sample HMR2 collected as part of a previous study near Barstow.

As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army at Fort Irwin National Training Center, the U.S. Geological Survey (USGS) evaluated unsaturated zone soil property data of cores from a newly drilled monitoring well site near a dry well and Four-plex baseball field. Measurements and observations are presented for cores from an initial drilling attempt (site ESW2A), which stopped at 85 feet below land surface due to equipment issues, and data are presented for cores from the successful drilling attempt (ESW2B) down to 240 feet below land surface. The two core sites are located approximately 6 feet from each other. Data measured on core material included gravimetric measurements of bulk water content, matric potential, and specific conductance of soil leachate samples.

As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army at Fort Irwin National Training Center, the U.S. Geological Survey (USGS) evaluated unsaturated zone soil property data of cores from a newly drilled monitoring well site near a dry well and Four-plex baseball field. Measurements and observations are presented for cores from an initial drilling attempt (site ESW2A), which stopped at 85 feet below land surface due to equipment issues, and data are presented for cores from the successful drilling attempt (ESW2B) down to 240 feet below land surface. The two core sites are located approximately 6 feet from each other. Data measured on core material included gravimetric measurements of bulk water content, matric potential, and specific conductance of soil leachate samples.

As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army at Fort Irwin National Training Center, the U.S. Geological Survey (USGS) evaluated unsaturated zone soil property data of cores from a borehole for a newly drilled monitoring well near a dry well and Four-plex baseball field. Cores were continuous from land surface down to 240 feet below land surface and were drilled by consultants to EPA using sonic rotary–a fluidless drilling technique. Data on this page consist of: 1) field drilling notes from USGS and consultants to EPA (GeoSystems Analysis, Inc., Tucson, Arizona); 2) field descriptions of core lithology–including grain size, sorting, color, mineralogy, moisture content and other distinguishing characteristics–done on site by USGS personnel; and 3) photos of the cores taken by USGS personnel–consisting of bagged cores in original core liners, and subsampled cores in plastic core boxes.

As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army at Fort Irwin National Training Center, the U.S. Geological Survey (USGS) evaluated unsaturated zone soil property data of cores from a borehole for a newly drilled monitoring well near a dry well and Four-plex baseball field. Cores were continuous from land surface down to 240 feet below land surface and were drilled by consultants to EPA using sonic rotary–a fluidless drilling technique. Data on this page consist of: 1) field drilling notes from USGS and consultants to EPA (GeoSystems Analysis, Inc., Tucson, Arizona); 2) field descriptions of core lithology–including grain size, sorting, color, mineralogy, moisture content and other distinguishing characteristics–done on site by USGS personnel; and 3) photos of the cores taken by USGS personnel–consisting of bagged cores in original core liners, and subsampled cores in plastic core boxes.

The U.S. Army Fort Irwin National Training Center (NTC), approximately 35 miles north-northeast of Barstow, California, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle Basins) within the NTC boundaries. In these basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, managed aquifer recharge using treated wastewater has offset water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (for example, wastewater disposal practices, landscape irrigation, and (or) leaking pipes). As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA) and the U.S. Army, the U.S. Geological Survey (USGS) collected eight electrical resistivity tomography surveys on irrigated fields in Irwin Basin. Borehole geophysical logs were collected in three monitoring well sites near one of the irrigated fields.

The U.S. Army Fort Irwin National Training Center (NTC), approximately 35 miles north-northeast of Barstow, California, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle Basins) within the NTC boundaries. In these basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, managed aquifer recharge using treated wastewater has offset water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (for example, wastewater disposal practices, landscape irrigation, and (or) leaking pipes). As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS) collected geophysical data to do a site characterization of an irrigated field (Four-plex baseball field) in the Irwin Basin. To aid in the understanding of the subsurface near the Four-plex baseball fields the USGS collected borehole geophysical data during 2018–2020. Natural gamma and neutron geophysical logs were collected in two monitoring wells that were installed by the EPA during 2018–19. Fluid resistivity, natural gamma, and electromagnetic induction logs were repeated in one of the EPA monitoring wells in February 2020; these types of geophysical logs also were collected at a nearby monitoring well on the eastern side of the Four-plex baseball field.

The U.S. Army Fort Irwin National Training Center (NTC), approximately 35 miles north-northeast of Barstow, California, obtains all of its potable water supply from three groundwater basins (Irwin, Langford, and Bicycle Basins) within the NTC boundaries. In these basins, groundwater withdrawals exceed natural recharge, resulting in water-level declines. However, managed aquifer recharge using treated wastewater has offset water-level declines in Irwin Basin. Additionally, localized water-quality changes have occurred in some parts of Irwin Basin as a result of human activities (for example, wastewater disposal practices, landscape irrigation, and (or) leaking pipes). As part of a research study in cooperation with the U.S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS) collected geophysical data to do a site characterization of an irrigated field (Four-plex baseball field) in the Irwin Basin. To aid in the understanding of the subsurface near the Four-plex baseball fields the USGS collected borehole geophysical data during 2018–2020. Natural gamma and neutron geophysical logs were collected in two monitoring wells that were installed by the EPA during 2018–19. Fluid resistivity, natural gamma, and electromagnetic induction logs were repeated in one of the EPA monitoring wells in February 2020; these types of geophysical logs also were collected at a nearby monitoring well on the eastern side of the Four-plex baseball field.

Abstract from SIR 2017-5079: This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass (Distichlis spicata) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale (Atriplex confertifolia) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush (Larrea tridentata) where the depth to groundwater was 110 m. Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ2H) and oxygen (δ18O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.

Abstract from SIR 2017-5079: This report documents methodology and results of a study to evaluate groundwater discharge by evapotranspiration (GWET) in sparsely vegetated areas of Amargosa Desert and improve understanding of hydrologic-continuum processes controlling groundwater discharge. Evapotranspiration and GWET rates were computed and characterized at three sites over 2 years using a combination of micrometeorological, unsaturated zone, and stable-isotope measurements. One site (Amargosa Flat Shallow [AFS]) was in a sparse and isolated area of saltgrass (Distichlis spicata) where the depth to groundwater was 3.8 meters (m). The second site (Amargosa Flat Deep [AFD]) was in a sparse cover of predominantly shadscale (Atriplex confertifolia) where the depth to groundwater was 5.3 m. The third site (Amargosa Desert Research Site [ADRS]), selected as a control site where GWET is assumed to be zero, was located in sparse vegetation dominated by creosote bush (Larrea tridentata) where the depth to groundwater was 110 m. Results indicated that capillary rise brought groundwater to within 0.9 m (at AFS) and 3 m (at AFD) of land surface, and that GWET rates were largely controlled by the slow but relatively persistent upward flow of water through the unsaturated zone in response to atmospheric-evaporative demands. Greater GWET at AFS (50 ± 20 millimeters per year [mm/yr]) than at AFD (16 ± 15 mm/yr) corresponded with its shallower depth to the capillary fringe and constantly higher soil-water content. The stable-isotope dataset for hydrogen (δ2H) and oxygen (δ18O) illustrated a broad range of plant-water-uptake scenarios. The AFS saltgrass and AFD shadscale responded to changing environmental conditions and their opportunistic water use included the time- and depth-variable uptake of unsaturated-zone water derived from a combination of groundwater and precipitation. These results can be used to estimate GWET in other areas of Amargosa Desert where hydrologic conditions are similar.