Science and Products
Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments
Natural perchlorate (ClO4−) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4− compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence...Jackson, W Andrew; Böhlke, John Karl; Andraski, Brian J.; Fahlquist, Lynne S.; Bexfield, Laura M.; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil C.; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta J.; Betancourt, Julio L.; Stonestrom, David A.; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.
The quality of our Nation's waters: water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008
About 8 million people rely on groundwater from the Mississippi embayment—Texas coastal uplands aquifer system for drinking water. The Mississippi River Valley alluvial aquifer also provides drinking water for domestic use in rural areas but is of primary importance to the region as a source of water for irrigation. Irrigation withdrawals...Kingsbury, James A.; Barlow, Jeannie R.; Katz, Brian G.; Welch, Heather L.; Tollett, Roland W.; Fahlquist, Lynne S.
Factors affecting public-supply well vulnerability in two karst aquifers
Karst aquifers occur in a range of climatic and geologic settings. Nonetheless, they are commonly characterized by their vulnerability to water-quality impairment. Two karst aquifers, the Edwards aquifer in south-central Texas and the Upper Floridan aquifer in western Florida, were investigated to assess factors that control the movement of...Musgrove, MaryLynn; Katz, Brian G.; Fahlquist, Lynne S.; Crandall, Christy A.; Lindgren, Richard J.
Assessing the vulnerability of public-supply wells to contamination—Edwards aquifer near San Antonio, Texas
This fact sheet highlights findings from the vulnerability study of a public-supply well field in San Antonio, Texas. The well field consists of six production wells that tap the Edwards aquifer. Typically, one or two wells are pumped at a time, yielding an average total of 20-21 million gallons per day. Water samples were collected from public-...Jagucki, Martha L.; Musgrove, MaryLynn; Lindgren, Richard J.; Fahlquist, Lynne; Eberts, Sandra M.
Simulations of groundwater flow and particle-tracking analysis in the zone of contribution to a public-supply well in San Antonio, Texas
In 2006, a public-supply well in San Antonio, Texas, was selected for intensive study to assess the vulnerability of public-supply wells in the Edwards aquifer to contamination by a variety of compounds. A local-scale, steady-state, three-dimensional numerical groundwater-flow model was developed and used in this study to evaluate the movement of...Lindgren, Richard L.; Houston, Natalie A.; Musgrove, MaryLynn; Fahlquist, Lynne S.; Kauffman, Leon J.
Hydrogeology, chemical characteristics, and water sources and pathways in the zone of contribution of a public-supply well in San Antonio, Texas
In 2001, the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey initiated a series of studies on the transport of anthropogenic and natural contaminants (TANC) to public-supply wells (PSWs). The main goal of the TANC project was to better understand the source, transport, and receptor factors that control contaminant...Musgrove, MaryLynn; Fahlquist, Lynne; Stanton, Gregory P.; Houston, Natalie A.; Lindgren, Richard J.
Geochemical evolution processes and water-quality observations based on results of the National Water-Quality Assessment Program in the San Antonio segment of the Edwards aquifer, 1996-2006
As part of the National Water-Quality Assessment Program, the U.S. Geological Survey collected and analyzed groundwater samples during 1996-2006 from the San Antonio segment of the Edwards aquifer of central Texas, a productive karst aquifer developed in Cretaceous-age carbonate rocks. These National Water-Quality Assessment Program studies...Musgrove, MaryLynn; Fahlquist, Lynne; Houston, Natalie A.; Lindgren, Richard J.; Ging, Patricia B.
Sources of groundwater based on Helium analyses in and near the freshwater/saline-water transition zone of the San Antonio segment of the Edwards Aquifer, South-Central Texas, 2002-03
This report evaluates dissolved noble gas data, specifically helium-3 and helium-4, collected by the U.S. Geological Survey, in cooperation with the San Antonio Water System, during 2002-03. Helium analyses are used to provide insight into the sources of groundwater in the freshwater/saline-water transition zone of the San Antonio segment of the...Hunt, Andrew G.; Lambert, Rebecca B.; Fahlquist, Lynne
Low-Level detections of halogenated volatile organic compounds in groundwater: Use in vulnerability assessments
Concentrations of halogenated volatile organic compounds (VOCs) were determined by gas chromatography (GC) with an electron-capture detector (GC-ECD) and by gas chromatography with mass spectrometry (GC-MS) in 109 groundwater samples from five study areas in the United States. In each case, the untreated water sample was used for drinking-water...Plummer, Niel; Busenberg, E.; Eberts, S.M.; Bexfield, L.M.; Brown, C.J.; Fahlquist, L.S.; Katz, B.G.; Landon, M.K.
Ground-Water Quality Beneath Irrigated Cropland of the Northern and Southern High Plains Aquifer, Nebraska and Texas, 2003-04
A study of the quality of ground water beneath irrigated cropland was completed for the northern and southern High Plains aquifer. Ground-water samples were collected from 30 water-table monitoring wells in the northern agricultural land-use (NAL) study area in Nebraska in 2004 and 29 water-table monitoring wells in the southern agricultural land-...Stanton, Jennifer S.; Fahlquist, Lynne
Widespread presence of naturally occurring perchlorate in high plains of Texas and New Mexico
Perchlorate (ClO4-) occurrence in groundwater has previously been linked to industrial releases and the historic use of Chilean nitrate fertilizers. However, recently a number of occurrences have been identified for which there is no obvious anthropogenic source. Groundwater from an area of 155 000 km2 in 56 counties in northwest Texas and eastern...Rajagopalan, S.; Anderson, T.A.; Fahlquist, L.; Rainwater, Ken A.; Ridley, M.; Jackson, W.A.
Quality of water in the Trinity and Edwards aquifers, south-central Texas, 1996-98
During 1996–98, the U.S. Geological Survey studied surface- and ground-water quality in south-central Texas. The ground-water components included the upper and middle zones (undifferentiated) of the Trinity aquifer in the Hill Country and the unconfined part (recharge zone) and confined part (artesian zone) of the Edwards aquifer in the Balcones...Fahlquist, Lynne; Ardis, Ann F.