Tracy Davis
Science and Products
Noble gas signatures constrain oil-field water as the carrier phase of hydrocarbons occurring in shallow aquifers in the San Joaquin Basin, USA
Noble gases record fluid interactions in multiphase subsurface environments through fractionation processes during fluid equilibration. Water in the presence of hydrocarbons at the subsurface acquires a distinct elemental signature due to the difference in solubility between these two fluids. We find the atmospheric noble gas signature in produced...
Karolyte, Ruta; Barry, Peter H.; Hunt, Andrew; Kulongoski, Justin T.; Tyne, R.L.; Davis, Tracy; Wright, Michael; McMahon, Peter B.; Ballentine, C.J. Relative risk of groundwater-quality degradation near California (USA) oil fields estimated from 3H, 14C, and 4He
Relative risks of groundwater-quality degradation near selected California oil fields are estimated by examining spatial and temporal patterns in chemical and isotopic data in the context of groundwater-age categories defined by tritium and carbon-14. In the Coastal basins, western San Joaquin Valley (SJV), and eastern SJV; 82, 76, and 0...
McMahon, Peter B.; Landon, Matthew K.; Davis, Tracy; Wright, Michael; Rosecrans, Celia Z.; Anders, Robert; Land, Michael; Kulongoski, Justin T.; Hunt, Andrew Groundwater quality of aquifers overlying the Oxnard Oil Field, Ventura County, California
Groundwater samples collected from irrigation, monitoring, and municipal supply wells near the Oxnard Oil Field were analyzed for chemical and isotopic tracers to evaluate if thermogenic gas or water from hydrocarbon-bearing formations have mixed with surrounding groundwater. New and historical data show no evidence of water from hydrocarbon-...
Rosecrans, Celia Z.; Landon, Matthew K.; Ransom, Katherine Marie; Gillespie, Janice M.; Kulongoski, Justin T.; Stephens, Michael J.; Hunt, Andrew G.; Shimabukuro, David H.; Davis, Tracy Probabilistic categorical groundwater salinity mapping from airborne electromagnetic data adjacent to California’s Lost Hills and Belridge oil fields
Growing water stress has led to emerging interest in protecting fresh and brackish groundwater as a potential supplement to water supplies and raised questions about factors that could affect the future quality of fresh and brackish aquifers. Limited well infrastructure, particularly in regions where elevated salinity has led to limited historical...
Ball, Lyndsay B.; Davis, Tracy; Minsley, Burke J.; Gillespie, Janice M.; Landon, Matthew K. 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, 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.