Tracy Davis
Science and Products
Groundwater salinity and the effects of produced water disposal in the Lost Hills-Belridge oilfields, Kern County, California
Increased oil and gas production in many areas has led to concerns over the effects these activities may be having on nearby groundwater quality. In this study we determine the lateral and vertical extent of groundwater with less than 10,000 milligrams per liter (mg/l) total dissolved solids (TDS) near the Lost Hills-Belridge oilfields in...
Gillespie, Janice M.; Davis, Tracy; Stephens, Michael J.; Ball, Lyndsay B.; Landon, Matthew K. Occurrence and sources of radium in groundwater associated with oil fields in the southern San Joaquin Valley, California
Geochemical data from 40 water wells were used to examine the occurrence and sources of radium (Ra) in groundwater associated with three oil fields in California (Fruitvale, Lost Hills, South Belridge). 226Ra+228Ra activities (range=0.010-0.51 Bq/L) exceeded the 0.185 Bq/L drinking-water standard in 18% of the wells (not drinking-water wells)....
McMahon, Peter B.; Avner Vengosh; Davis, Tracy; Landon, Matthew K.; Rebecca L. Tyne; Wright, Michael; Kulongoski, Justin T.; Hunt, Andrew G.; Peter H. Barry; A.J. Kondash; Z. Wang; Christopher J. Ballentine Mapping protected groundwater adjacent to oil and gas fields, San Joaquin Valley, California
Airborne electromagnetic (AEM) surveys are a major component of a regional study of groundwater quality adjacent to oil and gas fields in the San Joaquin Valley of California, USA. AEM resistivity models are being used to delineate groundwater salinity in an effort to locate groundwater adjacent to oil and gas fields that could have future...
Ball, Lyndsay B.; Gillespie, Janice M.; Minsley, Burke; Davis, Tracy; Landon, Matthew K. Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA
Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its...
McMahon, Peter B.; Kulongoski, Justin T.; Vengosh, Avner; Cozzarelli, Isabelle M.; Landon, Matthew K.; Kharaka, Yousif K.; Gillespie, Janice M.; Davis, Tracy
Prioritization of oil and gas fields for regional groundwater monitoring based on a preliminary assessment of petroleum resource development and proximity to California’s groundwater resources
The California State Water Resources Control Board initiated a regional monitoring program in July 2015 to determine where and to what degree groundwater quality may be adversely impacted by oil and gas development activities. A key issue in the implementation of the regional groundwater monitoring program is that each year, detailed...
Davis, Tracy; Landon, Matthew K.; Bennett V, George L.
Data from exploratory sampling of groundwater in selected oil and gas areas of coastal Los Angeles County and Kern and Kings Counties in southern San Joaquin Valley, 2014–15: California oil, gas, and groundwater project
Exploratory sampling of groundwater in coastal Los Angeles County and Kern and Kings Counties of the southern San Joaquin Valley was done by the U.S. Geological Survey from September 2014 through January 2015 as part of the California State Water Resources Control Board’s Water Quality in Areas of Oil and Gas Production Regional Groundwater...
Dillon, David B.; Davis, Tracy A.; Landon, Matthew K.; Land, Michael T.; Wright, Michael T.; Kulongoski, Justin T.
Groundwater quality in the Santa Barbara Coastal Plain, California
Groundwater provides more than 40 percent of California’s drinking water. To protect this vital resource, the State of California established the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The Priority Basin Project of the GAMA Program provides a comprehensive assessment of the State’s groundwater quality and increases public...
Davis, Tracy A.; Belitz, Kenneth
Status of groundwater quality in the Santa Barbara Study Unit, 2011: California GAMA Priority Basin Project
Groundwater quality in the 48-square-mile Santa Barbara study unit was investigated in 2011 as part of the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project. The study unit is mostly in Santa Barbara County and is in the Transverse and Selected Peninsular Ranges...
Davis, Tracy A.; Kulongoski, Justin T.
Groundwater-quality data in the Monterey–Salinas shallow aquifer study unit, 2013: Results from the California GAMA Program
Groundwater quality in the 3,016-square-mile Monterey–Salinas Shallow Aquifer study unit was investigated by the U.S. Geological Survey (USGS) from October 2012 to May 2013 as part of the California State Water Resources Control Board Groundwater Ambient Monitoring and Assessment (GAMA) Program’s Priority Basin Project. The GAMA Monterey–Salinas...
Goldrath, Dara A.; Kulongoski, Justin T.; Davis, Tracy A.
Groundwater-quality data in the Santa Cruz, San Gabriel, and Peninsular Ranges Hard Rock Aquifers study unit, 2011-2012: results from the California GAMA program
Groundwater quality in the 2,400-square-mile Santa Cruz, San Gabriel, and Peninsular Ranges Hard Rock Aquifers (Hard Rock) study unit was investigated by the U.S. Geological Survey (USGS) from March 2011 through March 2012, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA)...
Davis, Tracy A.; Shelton, Jennifer L.
Updated study reporting levels (SRLs) for trace-element data collected for the California Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project, October 2009-March 2013
Groundwater samples have been collected in California as part of statewide investigations of groundwater quality conducted by the U.S. Geological Survey for the Groundwater Ambient Monitoring and Assessment (GAMA) Priority Basin Project (PBP). The GAMA-PBP is being conducted in cooperation with the California State Water Resources Control Board to...
Davis, Tracy A.; Olsen, Lisa D.; Fram, Miranda S.; Belitz, Kenneth Statistical evaluation of variables affecting occurrence of hydrocarbons in aquifers used for public supply, California
The variables affecting the occurrence of hydrocarbons in aquifers used for public supply in California were assessed based on statistical evaluation of three large statewide datasets; gasoline oxygenates also were analyzed for comparison with hydrocarbons. Benzene is the most frequently detected (1.7%) compound among 17 hydrocarbons analyzed at...
Landon, Matthew K.; Burton, Carmen A.; Davis, Tracy A.; Belitz, Kenneth; Johnson, Tyler D.