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Science Quality and Integrity
The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 82,000 reports authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Sequestration and reoxidation of chromium in experimental microcosms
Groundwater containing hexavalent chromium, Cr(VI), downgradient from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert, 80 miles northeast of Los Angeles, California, is undergoing bioremediation using added ethanol as a reductant in a volume of the aquifer defined as the in situ reactive zone (IRZ). This treatment reduces Cr(VI) to trivalent chromium, Cr
Authors
Laurence G. Miller, Callum E. Bobb, Andrea L. Foster, Emily G. Wright, Stacy C. Bennett, Krishangi D. Groover, John A. Izbicki
Predevelopment water levels, groundwater recharge, and selected hydrologic properties of aquifer materials, Hinkley and Water Valleys, California
Hydrologic and geophysical data were collected to support updates to an existing groundwater-flow model of Hinkley Valley, California, in the Mojave Desert about 80 miles northeast of Los Angeles, California. These data provide information on predevelopment (pre-1930) water levels, groundwater recharge, and selected hydrologic properties of aquifer materials.A predevelopment groundwater-level map,
Authors
Krishangi D. Groover, John A. Izbicki, Whitney A. Seymour, Anthony A. Brown, Randall E. Bayless, Carole D. Johnson, Katherine L. Pappas, Gregory A. Smith, Dennis A. Clark, Joshua Larsen, Meghan C. Dick, Lorraine E. Flint, Christina L. Stamos, John G. Warden
Evaluation of natural and anthropogenic (human-made) hexavalent chromium
Hexavalent chromium, Cr(VI), was released between 1952 and 1964 from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station, in the Mojave Desert about 80 miles northeast of Los Angeles, California. Geologic, geochemical, and hydrologic data from more than 100 wells collected between March 2015 and November 2017 were interpreted using a summative-scale analysis to define the extent
Authors
John A. Izbicki, John G. Warden, Krishangi D. Groover, Whitney A. Seymour
Environmental tracers of groundwater source, age, and geochemical evolution
Hexavalent chromium, Cr(VI), was discharged in cooling wastewater to unlined surface ponds from 1952 to 1964 and reached the underlying unconsolidated aquifer at the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert, 80 miles northeast of Los Angeles, California. A suite of environmental tracers was analyzed in water samples collected from more than 100 wells
Authors
John G. Warden, John A. Izbicki, Jürgen Sültenfuß, Kathleen Scheiderich, John Fitzpatrick
Groundwater chemistry and hexavalent chromium
Water samples collected by the U.S. Geological Survey from more than 100 wells between March 2015 and November 2017 in Hinkley and Water Valleys, in the Mojave Desert 80 miles northeast of Los Angeles, California, were analyzed for field parameters, major ions, nutrients, and selected trace elements, including hexavalent chromium, Cr(VI). Water from most wells was alkaline and oxic. The pH ranged
Authors
John A. Izbicki, R. Blaine McCleskey, Carmen A. Burton, Dennis A. Clark, Gregory A. Smith
Analyses of regulatory water-quality data
Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert 80 miles northeast of Los Angeles, California. The Pacific Gas and Electric Company has monitored groundwater near Hinkley, California, for Cr(VI) and other constituents since the late 1980s. By June 2017, more than 20,00
Authors
John A. Izbicki, Whitney A. Seymour
Chromium in minerals and selected aquifer materials
Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from a Pacific Gas and Electric Company (PG&E) compressor station in Hinkley, California, in the western Mojave Desert 80 miles northeast of Los Angeles, California. In 2015, the extent of anthropogenic Cr(VI) in groundwater in Hinkley and Water Valleys was uncertain, but some Cr(VI) in groundwater may be naturally o
Authors
Krishangi D. Groover, John A. Izbicki, William Benzel, Jean Morrison, Andrea L. Foster
Survey of chromium and selected element concentrations in rock, alluvium, and core material
Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) compressor station in Hinkley, California, in the western Mojave Desert 80 miles northeast of Los Angeles, California. In 2015, the extent of anthropogenic Cr(VI) in groundwater in Hinkley and Water Valleys was uncertain, and some Cr(VI) in groundwater may be naturally
Authors
John A. Izbicki, Krishangi D. Groover
Introduction to study area hydrogeology, chromium sources, site history, and purpose of study
Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert 80 miles (mi) northeast of Los Angeles, California. Remediation began in 1992, and in 2010, site cleanup was projected to require between 10 and 95 years and was expected to cost between $36 and $176 million. A 2007 PG&E
Authors
John A. Izbicki, Krishangi D. Groover, David M. Miller, Whitney A. Seymour, John G. Warden, Laurence G. Miller
Natural and anthropogenic (human-made) hexavalent chromium, Cr(VI), in groundwater near a mapped plume, Hinkley, California
Between 1952 and 1964, hexavalent chromium, Cr(VI), was released into groundwater from the Pacific Gas and Electric Company (PG&E) Hinkley compressor station in the Mojave Desert 80 miles (mi) northeast of Los Angeles, California. Remediation began in 1992, and in 2010, site cleanup was projected to require between 10 and 95 years and was expected to cost between $36 and $176 million. A 2007 PG&E
Authors
John A. Izbicki
Surface fault displacement models for strike-slip faults
Fault displacement models (FDMs) are an essential component of the probabilistic fault displacement hazard analyses (PFDHA), much like ground motion models in the probabilistic seismic hazard analyses for ground motion hazards. In this study, we develop several principal surface FDMs for strike-slip earthquakes. The model development is based on analyses of the new and comprehensive fault displac
Authors
Brian S. J. Chiou, Rui Chen, Kate Thomas, Christopher W. D. Milliner, Timothy E. Dawson, Mark D. Petersen
Near-field receiving-water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California—2020
Trace-metal concentrations in sediment and in the clam Limecola petalum (World Register of Marine Species, 2020; formerly reported as Macoma balthica and M. petalum), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer (km) south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francis
Authors
Daniel J. Cain, Marie Noële Croteau, Janet K. Thompson, Francis Parchaso, A. Robin Stewart, Emily L. Zierdt Smith, Kelly H. Shrader, Le H. Kieu, Samuel N. Luoma