http://pubs.er.usgs.gov/ New Publications of the CA USGS May 17, 2013 http://pubs.usgs.gov/fs/2012/3111/ target="_blank" http://pubs.usgs.gov/fs/2012/3111/images/fs20123111_California_map.png The San Francisco Bay study unit is approximately 620 square miles and consists of the Marina, Lobos, Downtown, Islais Valley, South San Francisco, Visitacion Valley, Westside, and the Santa Clara Valley groundwater basins (California Department of Water Resources, 2003). These basins were grouped into one study area primarily on the basis of geography (Ray and others, 2009). Mar 29, 2013 Fact Sheet http://pubs.usgs.gov/sir/2012/5248/ target="_blank" http://pubs.usgs.gov/sir/2012/5248/images/cover.jpg The GAMA San Francisco Bay study was designed to provide a spatially unbiased assessment of the quality of untreated groundwater within the primary aquifer system, as well as a statistically consistent basis for comparing water quality throughout the State. The assessment is based on water-quality and ancillary data collected by the USGS from 79 wells in 2007 and is supplemented with water-quality data from the California Department of Public Health (CDPH) database. The primary aquifer system is defined by the depth interval of the wells listed in the CDPH database for the San Francisco Bay study unit. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifer system; shallower groundwater may be more vulnerable to surficial contamination. May 10, 2013 Scientific Investigations Report /pubs/ForrestEtAl2013.pdf target="_blank" /pubs/images/ForrestEtAl2013.png 2) were incapable of quantifying component proportions due to mixing of multiple water types. Based on these analyses, water samples collected from the wells were broadly classified as fresh groundwater, saline waters, hydrothermal fluids, or mixed hydrothermal fluids/meteoric water wells. ]]> May 8, 2013 Publication /pubs/SobronAlpers2013.pdf target="_blank" /pubs/images/SobronAlpers2013.png The Iron Mountain Mine Superfund Site near Redding, California, is a massive sulfide ore deposit that was mined for iron, silver, gold, copper, zinc, and pyrite intermittently for nearly 100 years. As a result, both water and air reached the sulfide deposits deep within the mountain, producing acid mine drainage consisting of sulfuric acid and heavy metals from the ore. Particularly, the drainage water from the Richmond Mine at Iron Mountain is among the most acidic waters naturally found on Earth. The mineralogy at Iron Mountain can serve as a proxy for understanding sulfate formation on Mars. Selected sulfate efflorescent salts from Iron Mountain, formed from extremely acidic waters via drainage from sulfide mining, have been characterized by means of Raman spectroscopy. Gypsum, ferricopiapite, copiapite, melanterite, coquimbite, and voltaite are found within the samples. This work has implications for Mars mineralogical and geochemical investigations as well as for terrestrial environmental investigations related to acid mine drainage contamination. May 2013 Publication http://pubs.usgs.gov/sir/2013/5009/ target="_blank" http://pubs.usgs.gov/sir/2013/5009/images/cover.jpg A method was developed to calculate annual county level pesticide use for selected herbicides, insecticides, and fungicides applied to agricultural crops grown in the conterminous United States from 1992 through 2009. Pesticide-use data compiled by proprietary surveys of farm operations located within Crop Reporting Districts were used in conjunction with annual harvested-crop acreage reported by the U.S. Department of Agriculture National Agricultural Statistics Service (NASS) to calculate use rates per harvested crop acre, or an 'estimated pesticide use' (EPest) rate, for each crop by year. Pesticide-use data were not available for all Crop Reporting Districts and years. When data were unavailable for a Crop Reporting District in a particular year, EPest extrapolated rates were calculated from adjoining or nearby Crop Reporting Districts to ensure that pesticide use was estimated for all counties that reported harvested-crop acreage. EPest rates were applied to county harvested-crop acreage differently to obtain EPest-low and EPest-high estimates of pesticide-use for counties and states, with the exception of use estimates for California, which were taken from annual Department of Pesticide Regulation Pesticide Use Reports. Apr 15, 2013 Scientific Investigations Report http://pubs.usgs.gov/of/2013/1065/ target="_blank" images/MuellerGronberg.png County-level nitrogen and phosphorus inputs from animal manure for the conterminous United States for 2002 were estimated from animal populations from the 2002 Census of Agriculture by using methods described in U.S. Geological Survey Scientific Investigations Report 2006-5012. These estimates of nitrogen and phosphorus from animal manure were compiled in support of the U.S. Geological Survey's National Water-Quality Assessment Program. Apr 15, 2013 Open File Report http://pubs.usgs.gov/sir/2013/5023/ target="_blank" http://pubs.usgs.gov/sir/2013/5023/images/cover.jpg The U.S. Geological Survey monitored atmospheric deposition of pesticides in the Central Valley of California during two studies in 2001 and 2002-04. The 2001 study sampled wet deposition (rain) and storm-drain runoff in the Modesto, California, area during the orchard dormant-spray season to examine the contribution of pesticide concentrations to storm runoff from rainfall. In the 2002-04 study, the number and extent of collection sites in the Central Valley were increased to determine the areal distribution of organophosphate insecticides and other pesticides, and also five more sample types were collected. These were dry deposition, bulk deposition, and three sample types collected from a soil box: aqueous phase in runoff, suspended sediment in runoff, and surficial-soil samples. This report provides concentration data and describes methods and quality assurance of sample collection and laboratory analysis for pesticide compounds in all samples collected from 16 sites. Each sample was analyzed for 41 currently used pesticides and 23 pesticide degradates, including oxygen analogs (oxons) of 9 organophosphate insecticides. Analytical results are presented by sample type and study period. Apr 11, 2013 Scientific Investigations Report http://pubs.usgs.gov/ds/756/ target="_blank" http://pubs.usgs.gov/ds/756/images/cover.jpg Beginning around 2000, abundance indices of four pelagic fishes (delta smelt, striped bass, longfin smelt, and threadfin shad) within the San Francisco Bay and Sacramento-San Joaquin Delta began to decline sharply (Sommer and others, 2007). These declines collectively became known as the pelagic organism decline (POD). No single cause has been linked to this decline, and current theories suggest that combinations of multiple stressors are likely to blame. Contaminants (including current-use pesticides) are one potential stressor being investigated for its role in the POD (Anderson, 2007). Pesticide concentration data collected by the U.S. Geological Survey (USGS) at multiple sites in the delta region over the past two decades are critical to understanding the potential effects of current-use pesticides on species of concern as well as the overall health of the delta ecosystem. Apr 4, 2013 Data Series http://pubs.usgs.gov/fs/2012/3136/ target="_blank" http://pubs.usgs.gov/fs/2012/3136/images/fig2.png The California State Water Resources Control Board's (SWRCB) GAMA Program is a comprehensive assessment of statewide groundwater quality in California. From 2004 to 2012, the GAMA Program's Priority Basin Project focused on assessing groundwater resources used for public drinking-water supplies. More than 2,000 public-supply wells were sampled by U.S. Geological Survey (USGS) for this effort. Starting in 2012, the GAMA Priority Basin Project began an assessment of water resources in shallow aquifers in California. These shallow aquifers provide water for domestic and small community-supply wells, which are often drilled to shallower depths in the groundwater system than public-supply wells. Shallow aquifers are of interest because shallow groundwater may respond more quickly and be more susceptible to contamination from human activities at the land surface, than the deeper aquifers. Mar 26, 2013 Fact Sheet /pubs/KentLandon2013.pdf target="_blank" /pubs/images/KentLandon2013.png Concentrations and temporal changes in concentrations of nitrate and total dissolved solids (TDS) in groundwater of the Bunker Hill, Lytle, Rialto, and Colton groundwater subbasins of the Upper Santa Ana Valley Groundwater Basin were evaluated to identify trends and factors that may be affecting trends. One hundred, thirty-one public-supply wells were selected for analysis based on the availability of data spanning at least 11 years between the late 1980s and the 2000s. Mar 15, 2013 Publication http://pubs.usgs.gov/ds/717/ target="_blank" http://pubs.usgs.gov/ds/717/images/cover.jpg Data were collected on the physical properties of unsaturated alluvial deposits, the chemical composition of leachate extracted from unsaturated alluvial deposits, the chemical and isotopic composition of groundwater and unsaturated-zone water, and the chemical composition of unsaturated-zone gas at four monitoring sites in the southwestern part of the Mojave Desert in the town of Joshua Tree, San Bernardino County, California. The presence of denitrifying and nitrate-reducing bacteria from unsaturated alluvial deposits was evaluated for two of these monitoring sites that underlie unsewered residential development. Mar 15, 2013 Data Series http://pubs.usgs.gov/ds/744/ target="_blank" images/BuchananMorgan.png Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2009 (October 1, 2008-September 30, 2009). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, one site in San Pablo Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2008 through September 2009. Calibration curves and plots of the processed data for each sensor also are presented. Mar 15, 2013 Data Series http://pubs.usgs.gov/ds/688/ target="_blank" http://pubs.usgs.gov/ds/688/images/cover.jpg Groundwater quality in the 39,000-square-kilometer Cascade Range and Modoc Plateau (CAMP) study unit was investigated by the U.S. Geological Survey (USGS) from July through October 2010, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP). The GAMA PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The CAMP study unit is the thirty-second study unit to be sampled as part of the GAMA PBP. Mar 6, 2013 Data Series http://pubs.usgs.gov/sir/2012/5228/ target="_blank" http://pubs.usgs.gov/sir/2012/5228/images/cover.jpg Beach water and sediment samples were collected along the Gulf of Mexico coast to assess differences in contaminant concentrations before and after landfall of Macondo-1 well oil released into the Gulf of Mexico from the sinking of the British Petroleum Corporation's Deepwater Horizon drilling platform. Samples were collected at 70 coastal sites between May 7 and July 7, 2010, to document baseline, or "pre-landfall" conditions. A subset of 48 sites was resampled during October 4 to 14, 2010, after oil had made landfall on the Gulf of Mexico coast, called the "post-landfall" sampling period, to determine if actionable concentrations of oil were present along shorelines. Feb 25, 2013 Publication /pubs/DrexlerEtAl2013.pdf target="_blank" images/Drexler.png Currently, little is known about the impact of climate change on groundwater recharge in the Sierra Nevada and southern Cascade Range of California or other mountainous regions of the world. The purpose of this study was to determine whether small alpine peatlands called fens can be used as whole-ecosystem gauges of groundwater recharge through time. Fens are sustained by groundwater discharge and are highly sensitive to changes in groundwater flow due to hydrologic disturbance including climate change. Seven fens in the Sierra Nevada and southern Cascade Range were studied over a 50-80 year period using historic aerial photography. In each aerial photograph, fen areas were identified as open lawn and partially treed areas that exhibited (1) dark brownish-green coloring or various shades of gray and black in black and white imagery and (2) mottling of colors and clustering of vegetation, which signified a distinct moss canopy with overlying clumped sedge vegetation. In addition to the aerial photography study, a climate analysis for the study sites was carried out using both measured data (U.S. Department of Agriculture Natural Resources Conservation Service SNOwpack TELemetry system) and modeled data (a downscaled version of the Parameter-elevation Regressions on Independent Slopes Model) for the period from 1951 to 2010. Feb 25, 2013 Publication /pubs/KulongoskiEtAl2013.pdf target="_blank" images/Kulongoski.png To investigate the source of volatiles and their relationship to the San Andreas Fault System (SAFS), 18 groundwater samples were collected from wells near the Big Bend section of the SAFS in southern California and analyzed for helium and carbon abundance and isotopes. Feb 15, 2013 Publication /pubs/HiltonFischerKulongoski2013.pdf target="_blank" images/Hilton.png The study of the geochemistry of gases pervades the Earth and Environmental Sciences. This is due in no small measure to the well-established thermodynamic properties of gases which allow their application to a variety of processes occurring over a wide spectrum of natural conditions. In this respect, both major and associated minor gases have been proven useful: indeed, the trace gases have been particularly important given their role as sensitive geochemical tracers. Examples where gas geochemistry places key constraints on geochemical processes include the degassing history of the solid Earth to form the atmosphere and oceans, the origin and migration characteristics of hydrocarbon deposits, the scale of climate variability, the P-T characteristics of geothermal reservoirs, and the dynamics of the earthquake cycle and volcanic activity, to name but a few. This volume continues this rich tradition with an eclectic selection of papers aimed at exploring and exploiting gas geochemistry over a myriad set of research themes. Feb 15, 2013 Publication /pubs/DeedsKulongoskiBelitz2012.pdf target="_blank" images/Deeds.png 6 were measured in groundwater samples collected from 312 wells across California at concentrations as low as 10^-12 grams per kilogram groundwater. The hVOCs detected are predominately anthropogenic (i.e., "ahVOCs") and as such their distribution delineates where groundwaters are impacted and susceptible to human activity. ahVOC detections were broadly consistent with air-saturated water concentrations in equilibrium with a combination of industrial-era global and regional hVOC atmospheric abundances. However, detection of ahVOCs in nearly all of the samples collected, including ancient groundwaters, suggests the presence of a sampling or analytical artifact that confounds interpretation of the very-low concentration ahVOC data.]]> Nov 29, 2012 Publication /pubs/Nowell_EtAl2012.pdf target="_blank" images/Nowell_EtAl.png Organic contaminants and trace elements were measured in bed sediments collected from streams in seven metropolitan study areas across the United States to assess concentrations in relation to urbanization. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, the pyrethroid insecticide bifenthrin, and several trace elements were significantly related to urbanization across study areas. Most contaminants (except bifenthrin, chromium, nickel) were significantly related to the total organic carbon (TOC) content of the sediments. Regression models explained 45-80% of the variability in individual contaminant concentrations using degree of urbanization, sediment-TOC, and study-area indicator variables (which represent the combined influence of unknown factors, such as chemical use or release, that are not captured by available explanatory variables). Nov 6, 2012 Publication /pubs/Morgan-KingSchoellhamer2012.pdf target="_blank" images/Morgan-King.png The study of the geochemistry of gases pervades the Earth and Environmental Sciences. This is due in no small measure to the well-established thermodynamic properties of gases which allow their application to a variety of processes occurring over a wide spectrum of natural conditions. In this respect, both major and associated minor gases have been proven useful: indeed, the trace gases have been particularly important given their role as sensitive geochemical tracers. Examples where gas geochemistry places key constraints on geochemical processes include the degassing history of the solid Earth to form the atmosphere and oceans, the origin and migration characteristics of hydrocarbon deposits, the scale of climate variability, the P-T characteristics of geothermal reservoirs, and the dynamics of the earthquake cycle and volcanic activity, to name but a few. This volume continues this rich tradition with an eclectic selection of papers aimed at exploring and exploiting gas geochemistry over a myriad set of research themes. Nov 4, 2012 Publication /pubs/BurowEtAl2012.pdf target="_blank" images/Burow.png A regional assessment of multi-decadal changes in nitrate concentrations was done using historical data and a spatially stratified non-biased approach. Data were stratified into physiographic subregions on the basis of geomorphology and soils data to represent zones of historical recharge and discharge patterns in the basin. Data were also stratified by depth to represent a shallow zone generally representing domestic drinking-water supplies and a deep zone generally representing public drinking-water supplies. These stratifications were designed to characterize the regional extent of groundwater with common redox and age characteristics, two factors expected to influence changes in nitrate concentrations over time. Oct 20, 2012 Publication /pubs/FlorsheimEtAl2011.pdf target="_blank" images/Florsheim.png The spatial and temporal variability of sediment sources, storage, and transport were investigated in a small agricultural watershed draining the Coast Ranges and Sacramento Valley in central California. Results of field, laboratory, and historical data analysis in the Willow Slough fluvial system document changes that transformed a transport-limited depositional system to an effective erosion and transport system, despite a large sediment supply. These changes were caused by a combination of factors: (i) an increase in transport capacity, and (ii) hydrologic alteration. Alteration of the riparian zone and drainage network pattern during the past ~ 150 years included a twofold increase in straightened channel segments along with a baselevel change from excavation that increased slope, and increased sediment transport capacity by ~ 7%. Hydrologic alteration from irrigation water contributions also increased transport capacity, by extending the period with potential for sediment transport and erosion by ~ 6 months/year. Sep 15, 2011 Publication http://pubs.usgs.gov/sir/2012/5094/ target="_blank" http://pubs.usgs.gov/sir/2012/5094/images/cover.jpg Groundwater quality in the approximately 860-square-mile Madera and Chowchilla Subbasins (Madera-Chowchilla study unit) of the San Joaquin Valley Basin was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in California's Central Valley region in parts of Madera, Merced, and Fresno Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The Project was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems in California. The primary aquifer system within each study unit is defined by the depth of the perforated or open intervals of the wells listed in the California Department of Public Health (CDPH) database of wells used for municipal and community drinking-water supply. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifer system; shallower groundwater may be more vulnerable to contamination from the surface. Feb 11, 2013 http://pubs.usgs.gov/fs/2012/3099/ Groundwater Quality in the Madera and Chowchilla Subbasins of the San Joaquin Valley, California Publication http://pubs.usgs.gov/ds/706/ target="_blank" http://pubs.usgs.gov/ds/706/images/cover.jpg Groundwater quality in the approximately 2,170-square-mile Western San Joaquin Valley (WSJV) study unit was investigated by the U.S. Geological Survey (USGS) from March to July 2010, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The WSJV study unit was the twenty-ninth study unit to be sampled as part of the GAMA-PBP. Jan 31, 2013 Data Series http://pubs.usgs.gov/of/2013/1016/ target="_blank" http://pubs.usgs.gov/of/2013/1016/images/cover.jpg The Merced River in the popular and picturesque eastern-most part of Yosemite Valley in Yosemite National Park, California, USA, has been extensively altered since the park was first conceived in 1864. Historical human trampling of streambanks has been suggested as the cause of substantial increases in stream width, and the construction of undersized stone bridges in the 1920s has been suggested as the major factor leading to an increase in overbank flooding due to deposition of bars and islands between the bridges. In response, the National Park Service at Yosemite National Park (YNP) requested a study of the hydraulic and geomorphic conditions affecting the most-heavily influenced part of the river, a 2.4-km reach in eastern Yosemite Valley extending from above the Tenaya Creek and Merced River confluence to below Housekeeping Bridge. As part of the study, present-day conditions were compared to historical conditions and several possible planning scenarios were investigated, including the removal of an elevated road berm and the removal of three undersized historic stone bridges identified by YNP as potential problems: Sugar Pine, Ahwahnee and Stoneman Bridges. This Open-File Report will be superseded at a later date by a Scientific Investigations Report. Jan 29, 2013 Open File Report http://pubs.usgs.gov/sir/2012/5139/ target="_blank" http://pubs.usgs.gov/sir/2012/5139/images/cover.jpg m- and p-xylenes, and o-xylene.]]> Jan 25, 2013 Publication http://pubs.usgs.gov/sir/2012/5040/ target="_blank" http://pubs.usgs.gov/sir/2012/5040/images/cover.jpg Groundwater quality in six areas in the California Desert Region (Owens, Antelope, Mojave, Coachella, Colorado River, and Indian Wells) was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The six Desert studies were designed to provide a spatially unbiased assessment of the quality of untreated groundwater in parts of the Desert and the Basin and Range hydrogeologic provinces, as well as a statistically consistent basis for comparing groundwater quality to other areas in California and across the Nation. Samples were collected by the USGS from September 2006 through April 2008 from 253 wells in Imperial, Inyo, Kern, Los Angeles, Mono, Riverside, and San Bernardino Counties. Two-hundred wells were selected using a spatially distributed, randomized grid-based method to provide a spatially unbiased representation of the study areas (grid wells), and fifty-three wells were sampled to provide additional insight into groundwater conditions (additional wells). Jan 10, 2013 Fact Sheet http://pubs.usgs.gov/fs/2012/3032/ target="_blank" http://pubs.usgs.gov/fs/2012/3032/images/fs20123032_California_map.png The Owens study area is approximately 1,030 square miles (2,668 square kilometers) and includes the Owens Valley groundwater basin (California Department of Water Resources, 2003). Owens Valley has a semiarid to arid climate, with average annual rainfall of about 6 inches (15 centimeters). The study area has internal drainage, with runoff primarily from the Sierra Nevada draining east to the Owens River, which flows south to Owens Lake dry lakebed at the southern end of the valley. Beginning in the early 1900s, the City of Los Angeles began diverting the flow of the Owens River to the Los Angeles Aqueduct, resulting in the evaporation of Owens Lake and the formation of the current Owens Lake dry lakebed. Land use in the study area is approximately 94 percent (%) natural, 5% agricultural, and 1% urban. The primary natural land cover is shrubland. The largest urban area is the city of Bishop (2010 population of 4,000). Jan 10, 2013 Fact Sheet http://pubs.usgs.gov/fs/2012/3034/ target="_blank" http://pubs.usgs.gov/fs/2012/3034/images/fs20123034_California_map.png The Colorado River study area is approximately 884 square miles (2,290 square kilometers) and includes the Needles, Palo Verde Mesa, Palo Verde Valley, and Yuma groundwater basins (California Department of Water Resources, 2003). The Colorado River study area has an arid climate and is part of the Sonoran Desert. Average annual rainfall is about 3 inches (8 centimeters). Land use in the study area is approximately 47 percent (%) natural (mostly shrubland), 47% agricultural, and 6% urban. The primary crops are pasture and hay. The largest urban area is the city of Blythe (2010 population of 21,000). Jan 10, 2013 Fact Sheet http://pubs.usgs.gov/fs/2012/3035/ target="_blank" http://pubs.usgs.gov/fs/2012/3035/images/fs20123035_California_map.png The Indian Wells study area is approximately 600 square miles (1,554 square kilometers) and includes the Indian Wells Valley groundwater basin (California Department of Water Resources, 2003). Indian Wells Valley has an arid climate and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). The study area has internal drainage, with runoff from the surrounding mountains draining towards dry lake beds in the lower parts of the valley. Land use in the study area is approximately 97.0 percent (%) natural, 0.4% agricultural, and 2.6% urban. The primary natural land cover is shrubland. The largest urban area is the city of Ridgecrest (2010 population of 28,000). Jan 10, 2013 Fact Sheet http://pubs.usgs.gov/fs/2012/3036/ target="_blank" http://pubs.usgs.gov/fs/2012/3036/images/fs20123036_California_map.png The Mojave study area is approximately 1,500 square miles (3,885 square kilometers) and includes four contiguous groundwater basins: Upper, Middle, and Lower Mojave River Groundwater Basins, and the El Mirage Valley (California Department of Water Resources, 2003). The Mojave study area has an arid climate, and is part of the Mojave Desert. Average annual rainfall is about 6 inches (15 centimeters). Land use in the study area is approximately 82 percent (%) natural (mostly shrubland), 4% agricultural, and 14% urban. The primary crops are pasture and hay. The largest urban areas are the cities of Victorville, Hesperia, and Apple Valley (2010 populations of 116,000, 90,000 and 69,000, respectively). Jan 10, 2013 Fact Sheet http://pubs.usgs.gov/fs/2012/3098/ target="_blank" http://pubs.usgs.gov/fs/2012/3098/images/fs20123098_California_map.png The Coachella study area is approximately 820 square miles (2,124 square kilometers) and includes the Coachella Valley groundwater basin (California Department of Water Resources, 2003). Coachella Valley has an arid climate, with average annual rainfall of about 6 inches (15 centimeters). The runoff from the surrounding mountains drains to rivers that flow east and south out of the study area to the Salton Sea. Land use in the study area is approximately 67 percent (%) natural, 21% agricultural, and 12% urban. The primary natural land cover is shrubland. The largest urban areas are the cities of Indio and Palm Springs (2010 populations of 76,000 and 44,000, respectively). Jan 10, 2013 Fact Sheet /pubs/BrownEtAl2013.pdf target="_blank" images/BrownEtAl.png Changes in the position of the low salinity zone, a habitat suitability index, turbidity, and water temperature modeled from four 100-year scenarios of climate change were evaluated for possible effects on delta smelt Hypomesus transpacificus, which is endemic to the Sacramento-San Joaquin Delta. The persistence of delta smelt in much of its current habitat into the next century appears uncertain. By midcentury, the position of the low salinity zone in the fall and the habitat suitability index converged on values only observed during the worst droughts of the baseline period (1969-2000). Projected higher water temperatures would render waters historically inhabited by delta smelt near the confluence of the Sacramento and San Joaquin rivers largely uninhabitable. However, the scenarios of climate change are based on assumptions that require caution in the interpretation of the results. Projections like these provide managers with a useful tool for anticipating long-term challenges to managing fish populations and possibly adapting water management to ameliorate those challenges. Jan 3, 2013 Publication http://pubs.usgs.gov/fs/2012/3132/ target="_blank" http://pubs.usgs.gov/fs/2012/3132/images/cover.jpg The Sacramento-San Joaquin River Delta (Delta) is the hub of California's water system and also an important habitat for imperiled fish and wildlife. Aquatic organisms are exposed to mixtures of pesticides that flow through the maze of Delta water channels from sources including agricultural, landscape, and urban pest-control applications. While we do not know all of the effects pesticides have on the ecosystem, there is evidence that they cause some damage to organisms in the Delta. Decades of USGS research have provided a good understanding of when, where, and how pesticides enter the Delta. However, pesticide use is continually changing. New field studies and methods are needed so that scientists can analyze which pesticides are present in the Delta, and at what concentrations, enabling them to estimate exposure and ultimate effects on organisms. Continuing research will provide resource managers and stakeholders with crucial information to manage the Delta wisely. Nov 20, 2012 Fact Sheet http://pubs.usgs.gov/sir/2012/5207/ target="_blank" images/Gronberg.png The U.S. Geological Survey's National Water-Quality Assessment program requires nutrient input for analysis of the national and regional assessment of water quality. Detailed information on nutrient inputs to the environment are needed to understand and address the many serious problems that arise from excess nutrients in the streams and groundwater of the Nation. This report updates estimated county-level farm and nonfarm nitrogen and phosphorus input from commercial fertilizer sales for the conterminous United States for 1987 through 2006. Estimates were calculated from the Association of American Plant Food Control Officials fertilizer sales data, Census of Agriculture fertilizer expenditures, and U.S. Census Bureau county population. A previous national approach for deriving farm and nonfarm fertilizer nutrient estimates was evaluated, and a revised method for selecting representative states to calculate national farm and nonfarm proportions was developed. A national approach was used to estimate farm and nonfarm fertilizer inputs because not all states distinguish between farm and nonfarm use, and the quality of fertilizer reporting varies from year to year. For states that distinguish between farm and nonfarm use, the spatial distribution of the ratios of nonfarm-to-total fertilizer estimates for nitrogen and phosphorus calculated using the national-based farm and nonfarm proportions were similar to the spatial distribution of the ratios generated using state-based farm and nonfarm proportions. Nov 19, 2012 Publication http://pubs.usgs.gov/of/2012/1173/ target="_blank" http://pubs.usgs.gov/of/2012/1173/images/cover.jpg The U.S. Geological Survey, in cooperation with the National Park Service and Whiskeytown National Recreation Area, performed a comprehensive aquatic biota survey of the upper Clear Creek watershed, Shasta County, California, during 2004-5. Data collected in this study can provide resource managers with information regarding aquatic resources, watershed degradation, and regional biodiversity within Whiskeytown National Recreation Area. Surveys of water chemistry, bed-sediment chemistry, algae assemblages, benthic macroinvertebrate assemblages, aquatic vertebrate assemblages, in-stream habitat characteristics, and sediment heterogeneity were conducted at 17 stream sites during both 2004 and 2005, with an additional 4 sites surveyed in 2005. To date, this survey represents the most comprehensive inventory of aquatic resources within Whiskeytown National Recreation Area, and this information can serve as a baseline for future monitoring efforts and to inform management decisions. Nov 6, 2012 Open File Report /pubs/IzbickiEtAl2012.pdf target="_blank" images/IzbickiEtAl.png Onsite wastewater treatment systems (OWTS) used to treat residential and commercial sewage near Malibu, California have been implicated as a possible source of fecal indicator bacteria (FIB) to Malibu Lagoon and the near-shore ocean. For this to occur, treated wastewater must first move through groundwater before discharging to the Lagoon or ocean. Oct 11, 2012 Publication http://pubs.usgs.gov/sir/2012/5206/ target="_blank" http://pubs.usgs.gov/sir/2012/5206/images/cover.jpg A method for the determination of the widely used herbicide diuron, three degradates of diuron, and six neonicotinoid insecticides in environmental water samples is described. Filtered water samples were extracted by using solid-phase extraction (SPE) with no additional cleanup steps. Quantification of the pesticides from the extracted water samples was done by using liquid chromatography with tandem mass spectrometry (LC/MS/MS). Oct 5, 2012 Publication http://pubs.usgs.gov/of/2012/1049/ target="_blank" http://pubs.usgs.gov/of/2012/1049/images/cover.jpg Two multiple-well monitoring sites were drilled in the Calaveras County portion of the Eastern San Joaquin Groundwater Subbasin, about 100 miles east of San Francisco, California, during December 2009 and January 2010. Site 3N/9E-12G1-4 was drilled to a depth of 503 feet below land surface (bls), and four wells were installed. Site 4N/9E-36A1-3 was drilled to a depth of 400 feet bls, and three wells were installed. Lithologic and geophysical data collected during test drilling indicated the presence of volcanic sands interspersed with lahar deposits that are characteristic of the Mehrten Formation to about 420 feet bls at site 12G1-4, and the presence of volcanic sands interspersed with clay that are characteristic of the Valley Springs Formation at site 36A1-3. In January 2010, water levels at site 12G1-4 ranged from 120 to 127 feet bls (the shallowest well at the site, 12G4, screened from 90 to 110 feet bls, was dry). Between May and November 2010, water levels declined as much as 22 feet in wells 12G1 and 12G2, the deepest wells at this site, and declined about 6 feet in shallower well 12G3. During this same period, water-levels declined less than 8 feet in the three wells at site 36A1-3. Water levels in all monitoring wells recovered to near-May-2010 levels by mid-spring 2011. Sep 28, 2012 Publication http://pubs.usgs.gov/fs/2012/3096/ target="_blank" http://pubs.usgs.gov/fs/2012/3096/images/fs20123096_California_map.png The Coastal Los Angeles Basin study unit is approximately 860 square miles and consists of the Santa Monica, Hollywood, West Coast, Central, and Orange County Coastal Plain groundwater basins (California Department of Water Resources, 2003). The basins are bounded in part by faults, including the Newport-Inglewood fault zone, and are filled with Holocene-, Pleistocene-, and Pliocene-age marine and alluvial sediments. The Central Basin and Orange County Coastal Plain are divided into a forebay zone on the northeast and a pressure zone in the center and southwest. The forebays consist of unconsolidated coarser sediment, and the pressure zones are characterized by lenses of coarser sediment divided into confined to semi-confined aquifers by lenses of finer sediments. The primary aquifer system in the study unit is defined as those parts of the aquifer system corresponding to the perforated intervals of wells listed in the California Department of Public Health (CDPH) database of public-supply wells. The majority of public-supply wells are drilled to depths of 510 to 1,145 feet, consist of solid casing from the land surface to a depth of about 300 to 510 feet, and are perforated below the solid casing. Water quality in the primary aquifer system may differ from that in the shallower and deeper parts of the aquifer systems. Sep 20, 2012 Fact Sheet http://pubs.usgs.gov/sir/2012/5048/ target="_blank" http://pubs.usgs.gov/sir/2012/5048/images/cover.jpg Groundwater quality in the approximately 860-square-mile (2,227-square-kilometer) Coastal Los Angeles Basin study unit (CLAB) was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study area is located in southern California in Los Angeles and Orange Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. Sep 20, 2012 Publication http://pubs.usgs.gov/tm/tm5c3/ target="_blank" http://pubs.usgs.gov/tm/tm5c3/images/cover.jpg A method for the determination of 119 pesticides in environmental sediment samples is described. The method was developed by the U.S. Geological Survey (USGS) in support of the National Water Quality Assessment (NAWQA) Program. The pesticides included in this method were chosen through prior prioritization. Herbicides, insecticides, and fungicides along with degradates are included in this method and span a variety of chemical classes including, but not limited to, chloroacetanilides, organochlorines, organophosphates, pyrethroids, triazines, and triazoles. Sep 13, 2012 Publication http://pubs.usgs.gov/ds/696/ target="_blank" http://pubs.usgs.gov/ds/696/images/cover.jpg Data were collected by the U.S. Geological Survey from 2003 through 2008 in the Eastern San Joaquin Groundwater Subbasin, 80 miles east of San Francisco, California, as part of a study of the increasing chloride concentrations in groundwater processes. Data collected include geologic, geophysical, chemical, and hydrologic data collected during and after the installation of five multiple-well monitoring sites, from three existing multiple-well sites, and from 79 selected public-supply, irrigation, and domestic wells. Each multiple-well monitoring site installed as part of this study contained three to five 2-inch diameter polyvinyl chloride (PVC)-cased wells ranging in depth from 68 to 880 feet below land surface. Continuous water-level data were collected from the 19 wells installed at these 5 sites and from 10 existing monitoring wells at 3 additional multiple-well sites in the study area. Thirty-one electromagnetic logs were collected seasonally from the deepest PVC-cased monitoring well at seven multiple-well sites. About 200 water samples were collected from 79 wells in the study area. Coupled well-bore flow data and depth-dependent water-quality data were collected from 12 production wells under pumped conditions, and well-bore flow data were collected from 10 additional wells under unpumped conditions. Sep 13, 2012 Publication http://pubs.usgs.gov/sir/2012/5065/ target="_blank" http://pubs.usgs.gov/sir/2012/5065/images/sir20125065.jpg The National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey (USGS) is conducting a regional analysis of water quality in the principal aquifer systems across the United States. The Southwest Principal Aquifers (SWPA) study is building a better understanding of the susceptibility and vulnerability of basin-fill aquifers in the region to groundwater contamination by synthesizing baseline knowledge of groundwater-quality conditions in 16 basins previously studied by the NAWQA Program. The improved understanding of aquifer susceptibility and vulnerability to contamination is assisting in the development of tools that water managers can use to assess and protect the quality of groundwater resources. Sep 11, 2012 Publication http://pubs.usgs.gov/ds/698/ target="_blank" http://pubs.usgs.gov/ds/698/images/ds698.jpg This product "Digital spatial data for predicted nitrate and arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study area" is a 1:250,000-scale vector spatial dataset developed as part of a regional Southwest Principal Aquifers (SWPA) study (Anning and others, 2012). The study examined the vulnerability of basin-fill aquifers in the southwestern United States to nitrate contamination and arsenic enrichment. Statistical models were developed by using the random forest classifier algorithm to predict concentrations of nitrate and arsenic across a model grid that represents local- and basin-scale measures of source, aquifer susceptibility, and geochemical conditions. Sep 11, 2012 Data Series http://pubs.usgs.gov/ds/697/ target="_blank" http://pubs.usgs.gov/ds/697/images/ds697.jpg This product "Digital spatial data for observed, predicted, and misclassification errors for observations in the training dataset for nitrate and arsenic concentrations in basin-fill aquifers in the Southwest Principal Aquifers study area" is a 1:250,000-scale point spatial dataset developed as part of a regional Southwest Principal Aquifers (SWPA) study (Anning and others, 2012). The study examined the vulnerability of basin-fill aquifers in the southwestern United States to nitrate contamination and arsenic enrichment. Statistical models were developed by using the random forest classifier algorithm to predict concentrations of nitrate and arsenic across a model grid that represents local- and basin-scale measures of source, aquifer susceptibility, and geochemical conditions. Sep 11, 2012 Data Series /pubs/LandonBelitz.pdf target="_blank" images/LandonBelitz.png Aug 23, 2012 Publication http://pubs.usgs.gov/ds/707/ target="_blank" http://pubs.usgs.gov/ds/707/images/cover.jpg Water and bed-sediment samples were collected by the U.S. Geological Survey (USGS) in 2009 and 2010 from 11 sites within California and 18 sites total in Colorado, Georgia, Idaho, Louisiana, Maine, and Oregon, and were analyzed for a suite of pesticides by the USGS. Water samples and bed-sediment samples were collected from perennial or seasonal ponds located in amphibian habitats in conjunction with research conducted by the USGS Amphibian Research and Monitoring Initiative and the USGS Toxic Substances Hydrology Program. Sites selected for this study in three of the states (California, Colorado, and Orgeon) have no direct pesticide application and are considered undeveloped and remote. Sites selected in Georgia, Idaho, Louisiana, and Maine were in close proximity to either agricultural or suburban areas. Aug 23, 2012 Data Series /pubs/Flint_BMC_California.pdf target="_blank" /pubs/images/Flint.png This paper outlines the production of 270-meter grid-scale maps for 14 climate and derivative hydrologic variables for a region that encompasses the State of California and all the streams that flow into it. The paper describes the Basin Characterization Model (BCM), a map-based mechanistic model used to process the hydrological variables. Three historic and three future time periods of 30 years were developed to summarize 180 years of monthly historic and future climate values. These comprise a standardized set of fine-scale climate data that were shared with 14 research groups, including the U.S. National Park Service and several University of California groups as part of this project. Aug 23, 2012 Publication http://pubs.usgs.gov/sir/2012/5052/ target="_blank" http://pubs.usgs.gov/sir/2012/5052/images/cover20125052.jpg Groundwater quality in the approximately 1,000-square-mile (2,590-square-kilometer) Upper Santa Ana Watershed (USAW) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in southern California in Riverside and San Bernardino Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. http://pubs.usgs.gov/fs/2012/3037/ Groundwater Quality in the Upper Santa Ana Watershed Study Unit, California: U.S. Geological Survey Fact Sheet 2012-3037 Aug 12, 2012 Publication http://pubs.usgs.gov/sir/2012/5132/ target="_blank" http://pubs.usgs.gov/sir/2012/5132/images/cover.jpg As a result of ongoing changes in climate, hydrologic and ecologic effects are being seen across the western United States. A regional study of how climate change affects water resources and habitats in the San Francisco Bay area relied on historical climate data and future projections of climate, which were downscaled to fine spatial scales for application to a regional water-balance model. Changes in climate, potential evapotranspiration, recharge, runoff, and climatic water deficit were modeled for the Bay Area. In addition, detailed studies in the Russian River Valley and Santa Cruz Mountains, which are on the northern and southern extremes of the Bay Area, respectively, were carried out in collaboration with local water agencies. Resource managers depend on science-based projections to inform planning exercises that result in competent adaptation to ongoing and future changes in water supply and environmental conditions. Aug 3, 2012 Publication http://pubs.usgs.gov/of/2012/1145/ target="_blank" http://pubs.usgs.gov/of/2012/1145/images/coverthb.jpg Historically, Forster's Terns (Sterna forsteri), American Avocets (Recurvirostra americana), and Black-necked Stilts (Himantopus mexicanus) were uncommon residents of San Francisco Bay, California (Grinnell and others, 1918; Grinnell and Wythe, 1927; Sibley, 1952). Presently, however, avocets and stilts are the two most abundant breeding shorebirds in San Francisco Bay (Stenzel and others, 2002; Rintoul and others, 2003). More than 4,000 avocets and 1,000 stilts, roughly 20 percent of their San Francisco Bay wintering populations, breed within the estuary, making San Francisco Bay the largest breeding area for these species on the Pacific Coast (Stenzel and others, 2002; Rintoul and others, 2003). Forster's Terns were first observed breeding in the San Francisco Bay in 1948 (110 nests); they had increased to over 4000 individuals by the 1980s (Sibley, 1952; Gill, 1977; Harvey and others, 1992; Carter and others, 1990) and were estimated at 2000-3000 for 1998-2002; (Strong and others, 2004). Aug 2, 2012 Publication http://pubs.usgs.gov/sir/2012/5130/ target="_blank" images/5130.png Flood-frequency information is important in the Central Valley region of California because of the high risk of catastrophic flooding. Most traditional flood-frequency studies focus on peak flows, but for the assessment of the adequacy of reservoirs, levees, other flood control structures, sustained flood flow (flood duration) frequency data are needed. This study focuses on rainfall or rain-on-snow floods, rather than the annual maximum, because rain events produce the largest floods in the region. A key to estimating flood-duration frequency is determining the regional skew for such data. Of the 50 sites used in this study to determine regional skew, 28 sites were considered to have little to no significant regulated flows, and for the 22 sites considered significantly regulated, unregulated daily flow data were synthesized by using reservoir storage changes and diversion records. The unregulated, annual maximum rainfall flood flows for selected durations (1-day, 3-day, 7-day, 15-day, and 30-day) for all 50 sites were furnished by the U.S. Army Corps of Engineers. Station skew was determined by using the expected moments algorithm program for fitting the Pearson Type 3 flood-frequency distribution to the logarithms of annual flood-duration data. Jul 26, 2012 Publication http://pubs.usgs.gov/sir/2012/5113/ target="_blank" http://pubs.usgs.gov/sir/2012/5113/images/coverthb.jpg Methods for estimating the magnitude and frequency of floods in California that are not substantially affected by regulation or diversions have been updated. Annual peak-flow data through water year 2006 were analyzed for 771 streamflow-gaging stations (streamgages) in California having 10 or more years of data. Flood-frequency estimates were computed for the streamgages by using the expected moments algorithm to fit a Pearson Type III distribution to logarithms of annual peak flows for each streamgage. Low-outlier and historic information were incorporated into the flood-frequency analysis, and a generalized Grubbs-Beck test was used to detect multiple potentially influential low outliers. Special methods for fitting the distribution were developed for streamgages in the desert region in southeastern California. Additionally, basin characteristics for the streamgages were computed by using a geographical information system. Jul 23, 2012 Publication http://pubs.usgs.gov/tm/4-f3/ target="_blank" http://pubs.usgs.gov/tm/4-f3/images/cover.jpg TracerLPM is an interactive Excel® (2007 or later) workbook program for evaluating groundwater age distributions from environmental tracer data by using lumped parameter models (LPMs). Lumped parameter models are athematical models of transport based on simplified aquifer geometry and flow configurations that account for effects of hydrodynamic dispersion or mixing within the aquifer, well bore, or discharge area. Five primary LPMs are included in the workbook: piston-flow model (PFM), exponential mixing model (EMM), exponential piston-flow model (EPM), partial exponential model (PEM), and dispersion model (DM). Binary mixing models (BMM) can be created by combining primary LPMs in various combinations. Travel time through the unsaturated zone can be included as an additional parameter. TracerLPM also allows users to enter age distributions determined from other methods, such as particle tracking results from numerical groundwater-flow models or from other LPMs not included in this program. Tracers of both young groundwater (anthropogenic atmospheric gases and isotopic substances indicating post-1940s recharge) and much older groundwater (carbon-14 and helium-4) can be interpreted simultaneously so that estimates of the groundwater age distribution for samples with a wide range of ages can be constrained. Jul 19, 2012 Publication /pubs/Toccalino_Patricia_Journal_Article.pdf target="_blank" images/Toccalino.png Chemical mixtures are prevalent in groundwater used for publicwater supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study,we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity ofmixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Jul 16, 2012 Publication http://pubs.usgs.gov/sir/2012/5100/ target="_blank" http://pubs.usgs.gov/sir/2012/5100/images/ca3437_cover_1_thumb.jpg The Big Bear Valley, located in the San Bernardino Mountains of southern California, has increased in population in recent years. Most of the water supply for the area is pumped from the alluvial deposits that form the Big Bear Valley groundwater basin. This study was conducted to better understand the thickness and structure of the groundwater basin in order to estimate the quantity and distribution of natural recharge to Big Bear Valley. Jul 16, 2012 Publication /pubs/Estuary-June2012_Measuring_Flow_Article.pdf target="_blank" images/estuary.png Stand on a tule island at the junction of two delta channels and you'd think you could tell which way the water was flowing. Surely anything that looks so much like a river naturally flows downstream, from the hills to the sea? But the Delta is not a one-way system, nor is nature entirely at the controls. Throw in ocean tides coming in and out, pumps directing water from here to there, and seasonal ups and downs, and the only people who can really tell which way the water is flowing at any given time or place aren't standing on a tule island. They're sitting in a dark room staring at computer screens showing the minute-by-minute measurements of the USGS flow station network. Jun 2012 Publication /pubs/ScanlonEtAl.pdf target="_blank" images/ScanlonEtAl.png Aquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ~50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km3 of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Jun 21, 2012 Publication /pubs/HenneberryEtAl.pdf target="_blank" images/HenneberryEtAl.png The objective was to assess the interaction of Fe coprecipitated with dissolved organic matter (DOM) and its effect on Fe (hydr)oxide crystallinity and DOM retention under abiotic reducing conditions. A Febased coagulant was reacted with DOM from an agricultural drain and the resulting precipitate (floc)was exposed to S(-II) and Fe(II). Solution concentrations of Fe(II/III) and DOM were monitored, floc crystallinity was determined using X-ray diffraction, and the composition and distribution of functional groups were assessed using scanning transmission X-ray microscopy (STXM) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Results indicate coprecipitation of Fe(III) with DOM forms a non-crystalline floc that withstands crystallization regardless of change in pH, Fe:DOM ratio and type of reductant added. Jun 21, 2012 Publication /pubs/HenneberryEtAl2011.pdf target="_blank" images/HenneberryEtAl2011.png The presence of inorganic mercury (IHg) and methylmercury (MeHg) in surface waters is a health concern worldwide. This study assessed the removal potential use of metal-based coagulants as a means to remove both dissolved IHg and MeHg from natural waters and provides information regarding the importance of Hg associations with the dissolved organic matter (DOM) fraction and metal hydroxides. Previous research indicated coagulants were not effective at removing Hg from solution; however these studies used high concentrations of Hg and did not reflect naturally occurring concentrations of Hg. In this study, water collected from an agricultural drain in the Sacramento-San Joaquin Delta was filtered to isolate the dissolved organic matter (DOM) fraction. The DOM was then treated with a range of coagulant doses to determine the efficacy of removing all forms of Hg from solution. Three industrial-grade coagulants were tested: ferric chloride, ferric sulfate, and polyaluminum chloride. Coagulation removed up to 85% of DOM from solution. Nov 13, 2010 Fact Sheet http://pubs.usgs.gov/fs/2011/3151/ target="_blank" http://pubs.usgs.gov/fs/2011/3151/images/fs20113151_fig01.png The Southeast San Joaquin Valley (SESJ) study unit is located in California's San Joaquin Valley and includes parts of Fresno, Kings, and Tulare Counties. The approximately 3,780-square-mile study unit was divided into four study areas: Kings, Kaweah, Tulare Lake, and Tule. The boundaries of these study areas correspond to the groundwater subbasins with the same names (California Department of Water Resources, 2003; Burton and Belitz, 2008). The SESJ study unit has hot, dry summers and cool, moist winters. Average annual rainfall ranges from 7 to 13 inches. The San Joaquin, Kings, and Tule Rivers are the primary streams flowing through the study unit. These rivers originate in the Sierra Nevada to the east. Jun 19, 2012 Fact Sheet http://pubs.usgs.gov/fs/2011/3150/ target="_blank" http://pubs.usgs.gov/fs/2011/3150/images/fs20113150_fig01.png The Kern County Subbasin (KERN) study unit is located at the southern end of California's San Joaquin Valley and consists of the Kern County groundwater subbasin (California Department of Water Resources, 2003; Shelton and others, 2008). The study unit covers about 3,000 square miles in Kern County. It is bounded by the Kern, Kings, and Tulare County lines to the north, the granitic bedrock of the Sierra Nevada and Tehachapi Mountains to the east and southeast, and the marine sediments of the San Emigdio Mountains and Coast Ranges to the southwest and west. The KERN study unit has long, hot summer days and cool nights, and mild, damp winters with dense fog. Average annual rainfall is about 6 inches. The Kern River, which originates in the Sierra Nevada, is the primary stream flowing through the study unit. Jun 19, 2012 Fact Sheet http://pubs.usgs.gov/sir/2011/5218/ target="_blank" http://pubs.usgs.gov/sir/2011/5218/images/cover.jpg Groundwater quality in the southern San Joaquin Valley was investigated from October 2005 through March 2006 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board and the Lawrence Livermore National Laboratory. There are two study units located in the southern San Joaquin Valley: the Southeast San Joaquin Valley (SESJ) study unit and the Kern County Subbasin (KERN) study unit. Jun 19, 2012 Publication /pubs/JA-conjunctive_use_model_climate_change.pdf target="_blank" images/HansonEtAl2.png Potential climate change effects on aspects of conjunctive management of water resources can be evaluated by linking climate models with fully integrated groundwater-surface water models. The objective of this study is to develop a modeling system that links global climate models with regional hydrologic models, using the California Central Valley as a case study. The new method is a supply and demand modeling framework that can be used to simulate and analyze potential climate change and conjunctive use. Jun 4, 2012 Publication http://pubs.usgs.gov/sir/2012/5045/ target="_blank" http://pubs.usgs.gov/sir/2012/5045/images/sac11-0422_cover_thumbnail.jpg The U.S. Geological Survey (USGS) has a periodic need to re-evaluate pesticide compounds in terms of priorities for inclusion in monitoring and studies and, thus, must also assess the current analytical capabilities for pesticide detection. To meet this need, a strategy has been developed to prioritize pesticides and degradates for analytical methods development. Screening procedures were developed to separately prioritize pesticide compounds in water and sediment. The procedures evaluate pesticide compounds in existing USGS analytical methods for water and sediment and compounds for which recent agricultural-use information was available. Measured occurrence (detection frequency and concentrations) in water and sediment, predicted concentrations in water and predicted likelihood of occurrence in sediment, potential toxicity to aquatic-life or humans, and priorities of other agencies or organizations, regulatory or otherwise, were considered. May 29, 2012 Publication http://pubs.usgs.gov/ds/659/ target="_blank" http://pubs.usgs.gov/ds/659/images/cover.jpg Groundwater quality in the 12,103-square-mile Borrego Valley, Central Desert, and Low-Use Basins of the Mojave and Sonoran Deserts (CLUB) study unit was investigated by the U.S. Geological Survey (USGS) from December 2008 to March 2010, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP). The GAMA-PBP was developed in response to the California Groundwater Quality Monitoring Act of 2001 and is being conducted in collaboration with the SWRCB and Lawrence Livermore National Laboratory (LLNL). The CLUB study unit was the twenty-eighth study unit to be sampled as part of the GAMA-PBP. May 21, 2012 Publication http://pubs.usgs.gov/sir/2011/5216/ target="_blank" http://pubs.usgs.gov/sir/2011/5216/images/cover.jpg Groundwater quality in the Tahoe-Martis, Central Sierra, and Southern Sierra study units was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The three study units are located in the Sierra Nevada region of California in parts of Nevada, Placer, El Dorado, Madera, Tulare, and Kern Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board, in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The project was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems used for drinking water. The primary aquifer systems (hereinafter, primary aquifers) for each study unit are defined by the depth of the screened or open intervals of the wells listed in the California Department of Public Health (CDPH) database of wells used for municipal and community drinking-water supply. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifers; shallower groundwater may be more vulnerable to contamination from the surface. Apr 10, 2012 Publication http://pubs.usgs.gov/fs/2011/3143/ target="_blank" http://pubs.usgs.gov/fs/2011/3143/images/fs20113143_California_map.png The Tahoe-Martis study unit is approximately 460 square miles and includes the groundwater basins on the south, north, and west shores of Lake Tahoe, and the Martis Valley groundwater basin (California Department of Water Resources, 2003). The study unit was divided into three study areas based primarily on geography: the Tahoe study area composed of the three Tahoe Valley basins, the Martis study area, and the Hard Rock study area composed of the parts of the watersheds surrounding the basins (Fram and others, 2009). Apr 10, 2012 Publication http://pubs.usgs.gov/fs/2012/3010/ target="_blank" http://pubs.usgs.gov/fs/2012/3010/images/fs20123010_California_map.png The Central Sierra Nevada study unit is approximately 370 square miles and includes no California Department of Water Resources defined groundwater basins. The study unit was divided into two study areas: the Coarse Gold study area corresponding to the watershed of the Fresno River above Hensley Lake, and the Wishon study area corresponding to the watershed of Willow Creek, a tributary of the San Joaquin River (Ferrari and others, 2008). Apr 10, 2012 Publication http://pubs.usgs.gov/fs/2012/3011/ target="_blank" http://pubs.usgs.gov/fs/2012/3011/images/fs20123011_California_map.png The Southern Sierra Nevada study unit is approximately 1,800 square miles; it includes six groundwater basins (California Department of Water Resources, 2003) and parts of the hard-rock watersheds surrounding the basins (Fram and Belitz, 2007). The primary aquifers in the Tehachapi-Cummings Valley basins in the southern part of the study unit consist of alluvial fan and floodplain sediments (mixtures of sand, silt, clay, gravel, cobbles, and boulders). The primary aquifers in the Kern River Valley basin in the northern part of the study unit are composed of fluvial sediments from the Kern River. Outside of and beneath the basins, the primary aquifers are fractured granitic and metamorphic rocks. Apr 10, 2012 Publication /pubs/KuivilaEtAl2012.pdf target="_blank" images/KuivilaEtAl.png A nationally consistent approach was used to assess the occurrence and potential sources of pyrethroid insecticides in stream bed sediments from seven metropolitan areas across the United States. One or more pyrethroids were detected in almost half of the samples, with bifenthrin detected the most frequently (41%) and in each metropolitan area. Cyhalothrin, cypermethrin, permethrin, and resmethrin were detected much less frequently. Pyrethroid concentrations and Hyalella azteca mortality in 28-d tests were lower than in most urban stream studies. Log-transformed total pyrethroid toxic units (TUs) were significantly correlated with survival and bifenthrin was likely responsible for the majority of the observed toxicity. Sampling sites spanned a wide range of urbanization and log-transformed total pyrethroid concentrations were significantly correlated with urban land use. Dallas/Fort Worth had the highest pyrethroid detection frequency (89%), the greatest number of pyrethroids (4), and some of the highest concentrations. Salt Lake City had a similar percentage of detections but only bifenthrin was detected and at lower concentrations. The variation in pyrethroid concentrations among metropolitan areas suggests regional differences in pyrethroid use and transport processes. This study shows that pyrethroids commonly occur in urban stream sediments and may be contributing to sediment toxicity across the country. Mar 28, 2012 Journal Article http://pubs.usgs.gov/sir/2011/5206/ target="_blank" http://pubs.usgs.gov/sir/2011/5206/images/cover.jpg Groundwater quality in the approximately 460-square-mile San Fernando-San Gabriel (FG) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study area is in Los Angeles County and includes Tertiary-Quaternary sedimentary basins situated within the Transverse Ranges of southern California. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. Mar 21, 2012 Publication http://pubs.usgs.gov/fs/2011/3139/ target="_blank" http://pubs.usgs.gov/fs/2011/3139/images/fs20113139_California_map.png Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created 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 access to groundwater-quality information. The San Fernando and San Gabriel groundwater basins constitute one of the study units being evaluated. Mar 21, 2012 Publication http://pubs.usgs.gov/of/2012/1044/ target="_blank" images/1044.png Advanced in situ optical water-quality sensors and new techniques for data analysis hold enormous promise for furthering scientific understanding of aquatic systems. These sensors measure important biogeochemical parameters for long deployments, enabling the capture of data at time scales over which they vary most meaningfully. The high-frequency, real-time water-quality data they generate provide opportunities for early warning of water-quality deterioration, trend detection, and science-based decision support. However, developing networks of optical sensors in freshwater systems that report reliable and comparable data across and between sites remains a challenge to the research and monitoring community. To address this, the U. S. Geological Survey (USGS) and the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) convened a joint 3-day workshop (June 8-10, 2011) at the National Conservation Training Center in Shepardstown, West Virginia, to explore ways to coordinate development of standards and applications for optical sensors, and improve handling, storing, and analyzing the continuous data they produce. Mar 14, 2012 Publication /pubs/Schoellhamer-2001-sudden-clearing.pdf target="_blank" images/Schoellhamer-2001-sudden-clearing.png The quantity of suspended sediment in an estuary is regulated either by transport, where energy or time needed to suspend sediment is limiting, or by supply, where the quantity of erodible sediment is limiting. This paper presents a hypothesis that suspended-sediment concentration (SSC) in estuaries can suddenly decrease when the threshold from transport to supply regulation is crossed as an erodible sediment pool is depleted. This study was motivated by a statistically significant 36% step decrease in SSC in San Francisco Bay from water years 1991-1998 to 1999-2007. A quantitative conceptual model of an estuary with an erodible sediment pool and transport or supply regulation of sediment transport is developed. Model results confirm that, if the regulation threshold was crossed in 1999, SSC would decrease rapidly after water year 1999 as observed. Estuaries with a similar history of a depositional sediment pulse followed by erosion may experience sudden clearing. Mar 12, 2012 Publication http://pubs.usgs.gov/sir/2011/5171 target="_blank" http://pubs.usgs.gov/sir/2011/5171/images/images_cover_thumb.jpg Stream temperature estimates under future climatic conditions were needed in support of fish production modeling for evaluation of effects of dam removal in the Klamath River Basin. To allow for the persistence of the Klamath River salmon fishery, an upcoming Secretarial Determination in 2012 will review potential changes in water quality and stream temperature to assess alternative scenarios, including dam removal. Daily stream temperature models were developed by using a regression model approach with simulated net solar radiation, vapor density deficit calculated on the basis of air temperature, and mean daily air temperature. Models were calibrated for 6 streams in the Lower, and 18 streams in the Upper, Klamath Basin by using measured stream temperatures for 1999-2008. Mar 9, 2012 Publication http://pubs.usgs.gov/tm/tm6a39/ target="_blank" http://pubs.usgs.gov/tm/tm6a39/images/cover.jpg A new evapotranspiration package for the U.S. Geological Survey's groundwater-flow model, MODFLOW, is documented. The Riparian Evapotranspiration Package (RIP-ET) provides flexibility in simulating riparian and wetland transpiration not provided by the Evapotranspiration (EVT) or Segmented Function Evapotranspiration (ETS1) Packages for MODFLOW 2005. This report describes how the RIP-ET package was conceptualized and provides input instructions, listings and explanations of the source code, and an example. Mar 6, 2012 Publication http://pubs.usgs.gov/ds/634/ target="_blank" images/634.png Suspended-sediment concentration data were collected by the U.S. Geological Survey in San Francisco Bay during water year 2008 (October 1, 2007-September 30, 2008). Optical sensors and water samples were used to monitor suspended-sediment concentration at two sites in Suisun Bay, two sites in Central San Francisco Bay, and one site in South San Francisco Bay. Sensors were positioned at two depths at most sites to help define the vertical variability of suspended sediments. Water samples were collected periodically and analyzed for concentrations of suspended sediment. The results of the analyses were used to calibrate the output of the optical sensors so that a record of suspended-sediment concentrations could be derived. This report presents the data-collection methods used and summarizes, in graphs, the suspended-sediment concentration data collected from October 2007 through September 2008. Calibration curves and plots of the processed data for each sensor also are presented. Feb 27, 2012 Publication http://pubs.usgs.gov/sir/2011/5234/ target="_blank" http://ca.water.usgs.gov/mojave/images/sm_general_location_map.jpg Mojave Water Agency (MWA), has constructed a series of regional water-table maps for intermittent years in a continuing effort to monitor groundwater conditions in the Mojave River and Morongo groundwater basins. The previously published data, which were used to construct these maps, can be accessed on the interactive map. The associated reports describing the groundwater conditions for the Mojave River groundwater basin for 1992 (Stamos and Predmore, 1995), the Morongo groundwater basin for 1994 (Trayler and Koczot, 1995), and for both groundwater basins for 1996 (Mendez and Christensen, 1997), for 1998 (Smith and Pimentel, 2000), for 2000 (Smith, 2002), for 2002 (Smith and others, 2004), for 2004 (Stamos and others, 2004), for 2006 (Stamos and others, 2007), for 2008 (Stamos and others, 2009), and for 2010 (Smith and others, 2011), can be accessed using this website. These water-level studies and those conducted since 2006 can be accessed in the Water-Level Studies.

]]> Feb 23, 2012 Publication http://pubs.usgs.gov/of/2011/1297/ target="_blank" http://pubs.usgs.gov/of/2011/1297/images/cover.jpg Feb 16, 2012 Publication /pubs/FlintFlint2011.pdf target="_blank" images/FlintFlint.png Evaluating the environmental impacts of climate change on water resources and biological components of the landscape is an integral part of hydrologic and ecological investigations, and the esultant land and resource management in the twenty-first century. Impacts of both climate and simulated hydrologic parameters on ecological processes are relevant at scales that reflect the heterogeneity and complexity of landscapes. At present, simulations of climate change available from global climate models [GCMs] require downscaling for hydrologic or ecological applications. Feb 10, 2011 Journal Article http://pubs.usgs.gov/fs/2012/3004/ target="_blank" images/3004.png 4^3-) and is also present in all life forms as an essential component of cellular material. In natural ecosystems, phosphorus is derived from the erosion of rocks and is conserved for plant growth as it is returned to the soil through animal waste and the decomposition of plant and animal tissue; but in agricultural systems, a portion of the phosphorus is removed with each harvest, especially since phosphorus is concentrated in the seeds and fruit. Phosphorus is added to soil by using chemical fertilizers, manure, and composted materials. Agricultural use of chemical phosphorus fertilizer, in the United States, in 2008 was 4,247,000 tons, which is an increase of 25 percent since 1964 (http://www.ers.usda.gov/Data/FertilizerUse/). Widely grown corn, soybeans, and wheat use the greatest amount of phosphorus fertilizer among agricultural crops.]]> Jan 27, 2012 Publication /pubs/IzbickiEtAl2012-2.pdf target="_blank" images/DeltaChromiumIzbickiEtAl.png 53/52Cr compositions from more than 50 samples collected within these plumes ranged from near 0% to almost 4% near the plume margins. Assuming only reductive fractionation of Cr(VI) to Cr(III) within the plume, apparent fractionation factors for delta^53/52Cr isotopes ranged from eapp = 0.3 to 0.4 within the Hinkley and Topock plumes, respectively, and only the El Mirage plume had a fractionation factor similar to the laboratory derived value of e = 3.5. One possible explanation for the difference between field and laboratory fractionation factors at the Hinkley and Topock sites is localized reductive fractionation of Cr(VI) to Cr(III), with subsequent advective mixing of native and contaminated water near the plume margin.]]> Jan 27, 2012 Publication /pubs/BergamaschiEtAl2011.pdf target="_blank" images/BergamaschiEtAl.png The flux of dissolved organic carbon (DOC) from mangrove swamps accounts for 10% of the global terrestrial flux of DOC to coastal oceans. Recent findings of high concentrations of mercury (Hg) and methylmercury (MeHg) in mangroves, in conjunction with the common co-occurrence of DOC and Hg species, have raised concerns that mercury fluxes may also be large. We used a novel approach to estimate export of DOC, Hg, and MeHg to coastal waters from a mangrovedominated estuary in Everglades National Park (Florida, USA). Dec 20, 2011 Publication http://pubs.usgs.gov/sir/2011/5154/ target="_blank" http://pubs.usgs.gov/sir/2011/5154/images/cover.jpg Groundwater quality in the approximately 3,900-square-mile San Diego Drainages Hydrogeologic Province (hereinafter San Diego) study unit was investigated from May through July 2004 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in southwestern California in the counties of San Diego, Riverside, and Orange. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. Dec 20, 2011 Publication http://pubs.usgs.gov/fs/2011/3111/ target="_blank" http://pubs.usgs.gov/fs/2011/3111/images/IP025298_California_map.png The San Diego study unit is approximately 3,900 square miles and consists of the Temecula Valley, Warner Valley, and 12 other alluvial basins (California Department of Water Resources, 2003). The study unit also consists of all areas outside defined groundwater basins that are within 3 kilometers of a public-supply well. The study unit was separated, based primarily on hydrogeologic settings, into four study areas: Temecula Valley, Warner Valley, Alluvial Basins, and Hard Rock (Wright and others, 2005). The sampling density for the Hard Rock study area, which consists of areas outside of groundwater basins, was much lower than for the other study areas. Consequently, aquifer proportions for the Hard Rock study area are not used to calculate the aquifer proportions shown by the pie charts. An assessment of groundwater quality for the Hard Rock study area can be found in Wright and Belitz, 2011. Dec 20, 2011 Publication http://pubs.usgs.gov/fs/2011/3061/ target="_blank" http://pubs.usgs.gov/fs/2011/3061/images/coverthb.gif Floods, hurricanes, and longer-term changes in climate and land use can have profound effects on water quality due to shifts in hydrologic flow paths, water residence time, precipitation patterns, connectivity between rivers and uplands, and many other factors. In order to understand and respond to changes in hydrology and water quality, resource managers and policy makers have a need for accurate and early indicators, as well as the ability to assess possible mechanisms and likely outcomes. In-situ optical sensors-those making continuous measurements of constituents by absorbance or fluorescence properties in the environment at timescales of minutes to years-have a long history in oceanography for developing highly resolved concentrations and fluxes, but are not commonly used in freshwater systems. The United States Geological Survey (USGS) has developed the Aquatic Real-Time Monitoring Network, with high-resolution optical data collection for organic carbon, nutrients, and sediment in large coastal rivers, along with continuous measurements of discharge, water temperature, and dissolved inorganic carbon. Jun 17, 2011 Publication http://pubs.usgs.gov/of/2011/1292/ target="_blank" http://pubs.usgs.gov/of/2011/1292/images/cover.jpg The U.S. Geological Survey (USGS), in cooperation with the Water Agency Division of the Santa Barbara County Department of Public Works, is evaluating the geohydrology and water availability of the Cuyama Valley, California. As part of this evaluation, the USGS installed the Cuyama Valley Kirschenmann Road multiple-well monitoring site (CVKR) in the South-Main subregion of the Cuyama Valley. The CVKR well site is designed to allow for the collection of depth-specific water-level and water-quality data. Data collected at this site provides information about the geology, hydrology, geophysics, and geochemistry of the local aquifer system, thus, enhancing the understanding of the geohydrologic framework of the Cuyama Valley. This report presents the construction information and initial geohydrologic data collected from the CVKR monitoring site, along with a brief comparison to selected supply and irrigation wells from the major subregions of the Cuyama Valley. Dec 15, 2011 Publication http://pubs.usgs.gov/sir/2011/5156/ target="_blank" http://pubs.usgs.gov/sir/2011/5156/images/cover.jpg Agua Caliente Spring, in downtown Palm Springs, California, has been used for recreation and medicinal therapy for hundreds of years and currently (2008) is the source of hot water for the Spa Resort owned by the Agua Caliente Band of the Cahuilla Indians. The Agua Caliente Spring is located about 1,500 feet east of the eastern front of the San Jacinto Mountains on the southeast-sloping alluvial plain of the Coachella Valley. The objectives of this study were to (1) define the geologic structure associated with the Agua Caliente Spring; (2) define the source(s), and possibly the age(s), of water discharged by the spring; (3) ascertain the seasonal and longer-term variability of the natural discharge, water temperature, and chemical characteristics of the spring water; (4) evaluate whether water-level declines in the regional aquifer will influence the temperature of the spring discharge; and, (5) estimate the quantity of spring water that leaks out of the water-collector tank at the spring orifice. Dec 7, 2011 Publication /pubs/JohnsonBelitz2012.pdf target="_blank" images/JohnsonBelitz2012.png Urban irrigation is an important component of the hydrologic cycle in many areas of the arid and semiarid western United States. This paper describes a new approach that uses readily available datasets to estimate the location and rate of urban irrigation. The approach provides a repeatable methodology at 1/3-square-km resolution across a large urbanized area (-square-km). For this study, Landsat Thematic Mapper satellite imagery, air photos, climatic records, and a land-use map were used to: (1) identify the fraction of irrigated landscaping in urban areas, and (2) estimate the monthly rate of irrigation being applied to those areas. The area chosen for this study was the San Fernando Valley in Southern California. Dec 7, 2011 Publication /pubs/DomagalskiJohnson2011.pdf target="_blank" images/DomagalskiJohnson2011.png Concentrations of dissolved orthophosphate (ortho P) in the unsaturated zone, groundwater, tile drains, and groundwater/stream water interfaces were assessed in five agricultural watersheds to determine the potential for subsurface transport. Concentrations of iron oxides were measured in the aquifer material and adsorption of ortho P on oxide surfaces was assessed by geochemical modeling. Attenuation of ortho P in these aquifers was attributed primarily to sorption onto iron oxides, and in one location onto clay minerals. Only one location showed a clear indication of phosphorus transport to a stream from groundwater discharge, although groundwater did contribute to the stream load elsewhere. Subsurface ortho P movement at a site in California resulted in a plume down gradient from orchards, which was attenuated by a 200 m thick riparian zone with natural vegetation. Iron oxides had an effect on phosphorus movement and concentrations at all locations, and groundwater chemistry, especially pH, exerted a major control on the amount of phosphorus adsorbed. Groundwater pH at a site in Maryland was below 5 and that resulted in complete sequestration of phosphorus and no movement toward the stream. Geochemical modeling indicated that as the surfaces approached saturation, groundwater concentrations of ortho P rise rapidly. Oct 28, 2011 Journal Article http://pubs.usgs.gov/of/2011/1271/ target="_blank" images/1271.png Beach water and sediment samples were collected along the Gulf of Mexico coast to assess differences in contaminant concentrations before and after landfall of Macondo-1 well oil released into the Gulf of Mexico from the sinking of the British Petroleum Corporation's Deepwater Horizon drilling platform. Samples were collected at 70 coastal sites on the Gulf of Mexico between May 7 and July 7, 2010, to document baseline, "pre-landfall" conditions. A subset of these sites was resampled during October 4 to 14, 2010, after oil had made landfall on the Gulf of Mexico coast ("post-landfall") to determine if actionable concentrations of oil were present along shorelines. Oct 19, 2011 Publication http://pubs.usgs.gov/ds/610/ target="_blank" http://pubs.usgs.gov/ds/610/images/coverthb.jpg Since 2003, the U.S. Geological Survey, in cooperation with the Sonoma County Water Agency, has been collecting chemical, microbiological, and isotopic data from surface-water and groundwater sites in Mendocino and Sonoma Counties, California. The investigation is being conducted to determine water-quality baseline conditions for the Russian River during the summer months and to characterize the water-quality in the area of the Sonoma County Water Agency's water-supply facility where Russian River water is diverted and treated by riverbank filtration. This report is a compilation of the hydrologic and water-quality data collected from 14 Russian River sites, 8 tributary sites, 1 gravel-terrace pit site, 14 groundwater wells, and a wastewater treatment plant between the city of Ukiah and the town of Duncans Mills for the period August 2005 through October 2010. Oct 13, 2011 Publication http://pubs.usgs.gov/ds/600/ target="_blank" http://pubs.usgs.gov/ds/600/images/sac11-0395_cover_thumbnail.jpg Water and sediment (bed and suspended) were collected from January 2008 through October 2009 from 12 sites in 3 of the largest watersheds along California's Central Coast (Pajaro, Salinas, and Santa Maria Rivers) and analyzed for a suite of pesticides by the U.S. Geological Survey. Water samples were collected in each watershed from the estuaries and major tributaries during 4 storm events and 11 dry season sampling events in 2008 and 2009. Bed sediments were collected from depositional zones at the tributary sampling sites three times over the course of the study. Suspended sediment samples were collected from the major tributaries during the four storm events and in the tributaries and estuaries during three dry season sampling events in 2009. Sep 30, 2011 Publication http://pubs.usgs.gov/sir/2011/5058/ target="_blank" http://pubs.usgs.gov/sir/2011/5058/images/cover.jpg Groundwater quality in the approximately 1,000 square mile (2,590-square-km) Monterey Bay and Salinas Valley Basins (MS) study unit was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in central California in Monterey, Santa Cruz, and San Luis Obispo Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. http://pubs.usgs.gov/fs/2011/3089/ Groundwater Quality in the Monterey Bay and Salinas Valley Groundwater Basins, California: U.S. Geological Survey Fact Sheet 2011-3089 Sep 26, 2011 Publication http://pubs.usgs.gov/sir/2011/5052/ target="_blank" http://pubs.usgs.gov/sir/2011/5052/images/cover.jpg Groundwater quality in the approximately 460-square-mile Santa Clara River Valley study unit was investigated from April through June 2007 as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The GAMA Priority Basin Project is conducted by the U.S. Geological Survey (USGS) in collaboration with the California State Water Resources Control Board and the Lawrence Livermore National Laboratory. The Santa Clara River Valley study unit contains eight groundwater basins located in Ventura and Los Angeles Counties and is within the Transverse and Selected Peninsular Ranges hydrogeologic province. http://pubs.usgs.gov/fs/2011/3055/ Groundwater Quality in the Santa Clara River Valley, California: U.S. Geological Survey Fact Sheet 2011-3055 Sep 26, 2011 Publication http://pubs.usgs.gov/ds/609 target="_blank" http://pubs.usgs.gov/ds/609/images/cover.jpg Groundwater quality in the 633-square-mile Northern Coast Ranges (NOCO) study unit was investigated by the U.S. Geological Survey (USGS) from June to November 2009, as part of the California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring and Assessment (GAMA) Program's Priority Basin Project (PBP) and the U.S. Geological Survey National Water-Quality Assessment Program (NAWQA). Sep 19, 2011 Publication http://pubs.usgs.gov/sir/2011/5141/ target="_blank" http://pubs.usgs.gov/sir/2011/5141/images/cover.jpg In 2009, the U.S. Geological Survey, in cooperation with the City of Santa Cruz, conducted bathymetric and topographic surveys to determine the water storage capacity of, and the loss of capacity owing to sedimentation in, Loch Lomond Reservoir in Santa Cruz County, California. The topographic survey was done as a supplement to the bathymetric survey to obtain information about temporal changes in the upper reach of the reservoir where the water is shallow or the reservoir may be dry, as well as to obtain information about shoreline changes throughout the reservoir. Sep 20, 2011 Publication http://pubs.usgs.gov/sir/2009/5219/ target="_blank" http://pubs.usgs.gov/sir/2009/5219/images/cover.jpg A watershed model using Hydrologic Simulation Program-FORTRAN (HSPF) was developed for the urbanized Chino Basin in southern California to simulate the transport of pathogen indicator bacteria, evaluate the flow-component and land-use contributions to bacteria contamination and water-quality degradation throughout the basin, and develop a better understanding of the potential effects of climate and land-use change on water quality. Jul 20, 2011 Publication /pubs/OLearyEtAl2012.pdf target="_blank" images/OLearyEtAl.png Jul 08, 2011 Journal Article /pubs/frambelitz2011pharms.pdf target="_blank" http://ca.water.usgs.gov/images/framarticle.png Pharmaceutical compounds may enter the environment by many pathways, including discharge of treated wastewater, seepage from landfills, septic systems, and sewer lines, and runoff from animal wastes and land application of manure fertilizers. Pharmaceutical compounds were detected at low concentrations in 2.3% of 1231 samples of groundwater used for public drinking-water supply in California. Samples were collected statewide for the California State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment (GAMA) Program. http://www.adobe.com/products/acrobat/readstep.html Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge Jul 05, 2011 Publication http://pubs.usgs.gov/fs/2011/3060/ target="_blank" images/3060_2.png The U.S. Geological Survey, in cooperation with Federal, State, and local agencies, obtains a large amount of data pertaining to the groundwater resources of California each water year (October 1-September 30). These data constitute a valuable database for developing an improved understanding of the water resources of the State. This Fact Sheet serves as an index to groundwater data for Water Year 2010. It contains a map of California showing the number of wells (by county) with available water-level or water-quality data for Water Year 2010 and instructions for obtaining this and other groundwater information contained in the databases of the U.S. Geological Survey, California Water Science Center. Jun 27, 2011 Publication /pubs/ChiuNishikawaMartin2012.pdf target="_blank" http://ca.water.usgs.gov/images/groundWaterCover.gif Hi-Desert Water District (HDWD), the primary water-management agency in the Warren groundwater subbasin, California (Figure 1), plans to construct a waste water treatment plant to reduce future septic-tank effluent from reaching the groundwater system. The treated waste water will be reclaimed by recharging the groundwater basin via recharge ponds as part of a larger conjunctive-use strategy. HDWD wishes to identify the least-cost conjunctive-use strategies that control groundwater levels, meet California State regulations, meet water-supply demand, and identify the optimal locations of new pumping wells. Jun 02, 2011 Publication http://pubs.usgs.gov/sir/2010/5249/ target="_blank" http://pubs.usgs.gov/sir/2010/5249/images/cover.jpg The Marine Corps Air Ground Combat Center (MCAGCC) Twentynine Palms, California, overlies the Surprise Spring, Deadman, Mesquite, and Mainside subbasins of the Morongo groundwater basin in the southern Mojave Desert. Groundwater pumpage in the Surprise Spring subbasin has caused groundwater levels in the subbasin to decline by as much as 190 feet (ft) from 1953 through 2007. Groundwater from the other subbasins contains relatively high concentrations of fluoride, arsenic, and (or) dissolved solids, making it unsuitable for potable uses without treatment. The U.S. Geological Survey, in cooperation with the MCAGCC, completed this study to better understand groundwater resources in the area and to help establish a long-term strategy for regional water-resource development. Jun 28, 2011 Publication http://pubs.usgs.gov/fs/2011/3061/ target="_blank" http://pubs.usgs.gov/fs/2011/3061/images/coverthb.gif The United States Geological Survey (USGS) has developed the Aquatic Real-Time Monitoring Network, with high-resolution optical data collection for organic carbon, nutrients, and sediment in large coastal rivers, along with continuous measurements of discharge, water temperature, and dissolved inorganic carbon. The collecting of continuous water-quality data in the Nation's waterways has revealed temporal trends and spatial patterns in constituents that traditional sampling approaches fail to capture, and will serve a critical role in monitoring, assessment and decision-making in a rapidly changing landscape. Jun 17, 2011 Publication http://pubs.usgs.gov/fs/2011/3060/ target="_blank" images/3060.png The U.S. Geological Survey, in cooperation with Federal, State, and local agencies, obtains a large amount of data pertaining to the groundwater resources of California each water year (October 1-September 30). These data constitute a valuable database for developing an improved understanding of the water resources of the State. This Fact Sheet serves as an index to groundwater data for Water Year 2010. It contains a map of California showing the number of wells (by county) with available water-level or water-quality data for Water Year 2010 (fig. 1) and instructions for obtaining this and other groundwater information contained in the databases of the U.S. Geological Survey, California Water Science Center. From 1985 to 1993, data were published in the annual report "Water Resources Data for California, Volume 5. Ground-Water Data"; prior to 1985, the data were published in U.S. Geological Survey Water-Supply Papers. Jun 27, 2011 Publication http://pubs.usgs.gov/of/2011/1091/ target="_blank" http://pubs.usgs.gov/of/2011/1091/images/cover_ofr_2011-1091_thumbnail.jpg Each year, over 550 million people visit California's public beaches. To protect beach-goers from exposure to waterborne disease, California state law requires water-quality monitoring for fecal indicator bacteria (FIB), such as enterococci and Escherichia coli (E. coli), at beaches having more than 50,000 yearly visitors. FIB are used to assess the microbiological quality of water because, although not typically disease causing, they are correlated with the occurrence of certain waterborne diseases. Tests show that FIB concentrations occasionally exceed U.S. Environmental Protection Agency (USEPA) public health standards for recreational water in Malibu Lagoon and at several Malibu beaches (Regional Water Quality Control Board, 2009). May 13, 2011 Publication http://pubs.usgs.gov/sir/2010/5228/ target="_blank" http://pubs.usgs.gov/sir/2010/5228/images/cover.jpg A comprehensive database was assembled for the Sacramento, San Joaquin, and Santa Ana Basins in California on nutrient concentrations, flows, and point and nonpoint sources of nutrients for 1975-2004. Most of the data on nutrient concentrations (nitrate, ammonia, total nitrogen, orthophosphate, and total phosphorus) were from the U.S. Geological Survey's National Water Information System database (35.2 percent), the California Department of Water Resources (21.9 percent), the University of California at Davis (21.6 percent), and the U.S. Environmental Protection Agency's STOrage and RETrieval database (20.0 percent). Mar 28, 2011 Publication http://pubs.usgs.gov/sir/2010/5260/ target="_blank" http://pubs.usgs.gov/sir/2010/5260/images/cover.jpg Improved flood-frequency information is important throughout California in general and in the Sacramento-San Joaquin River Basin in particular, because of an extensive network of flood-control levees and the risk of catastrophic flooding. A key first step in updating flood-frequency information is determining regional skew. Mar 24, 2011 Publication /pubs/MajzlanEtAl2011.pdf target="_blank" images/Majzlan.png 2O₃/FeO): szomolnokite, rozenite, siderotil, halotrichite, romerite, voltaite, copiapite, monoclinic Fe₂(SO₄)₃, Fe₂(SO₄)₃·5H₂O, kornelite, coquimbite, Fe (SO₄)(OH), jarosite and rhomboclase. Fourier transform infrared spectra in the region 750-4000 cm^-1 are presented for all studied phases.]]> Mar 17, 2011 Publication /pubs/PellerinEtAl2011.pdf target="_blank" images/PellerinEtAl.png In seasonally snow covered catchments, snowmelt often represents the single largest hydrologic event driving annual water yields (Sebestyen et al. 2009; Oczkowski et al. 2006; Boyer et al. 1997; Hornberger et al. 1994; Murdoch and Stoddard 1992) and has important implications for catchment nutrient and organic matter budgets (Sebestyen et al. 2008, 2009; Mitchell et al. 1996). Climate change is predicted to alter snowmelt runoff in upland forested catchments in the northeastern U.S. through the next century (Hayhoe et al. 2007), with changes in streamflow linked to an increase in the proportion of winter precipitation as rainfall, a decrease in snowpack depth, and earlier spring melt (Huntington et al. 2004, 2009; Hodgkins and Dudley 2006a, b). Therefore, a better understanding of snowmelt dynamics and constituent variability is needed to assess the dominant drivers and the potential effects of climate change on downstream yields of nutrients and organic matter. Mar 11, 2011 Journal Article http://pubs.usgs.gov/fs/2011/3006/ target="_blank" http://pubs.usgs.gov/fs/2011/3006/images/California_map.png Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created 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 access to groundwater-quality information. The Southern Sacramento Valley is one of the study units being evaluated. Apr 27, 2011 Publication http://pubs.usgs.gov/fs/2011/3005/ target="_blank" http://pubs.usgs.gov/fs/2011/3005/images/California_map.png Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created 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 access to groundwater-quality information. The Middle Sacramento Valley is one of the study units being evaluated. Apr 27, 2011 Publication http://pubs.usgs.gov/fs/2011/3004/ target="_blank" http://pubs.usgs.gov/fs/2011/3004/images/California_map.png Groundwater provides more than 40 percent of California's drinking water. To protect this vital resource, the State of California created 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 access to groundwater-quality information. The Northern Sacramento Valley is one of the study units being evaluated. Apr 27, 2011 Publication http://pubs.usgs.gov/sir/2011/5002/ target="_blank" http://pubs.usgs.gov/sir/2011/5002/images/cover.jpg Groundwater quality in the Southern, Middle, and Northern Sacramento Valley study units was investigated as part of the Priority Basin Project of the Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study units are located in California's Central Valley and include parts of Butte, Colusa, Glenn, Placer, Sacramento, Shasta, Solano, Sutter, Tehama, Yolo, and Yuba Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey and the Lawrence Livermore National Laboratory. Apr 27, 2011 Publication http://pubs.usgs.gov/sir/2010/5228/ target="_blank" http://pubs.usgs.gov/sir/2010/5228/images/cover.jpg A comprehensive database was assembled for the Sacramento, San Joaquin, and Santa Ana Basins in California on nutrient concentrations, flows, and point and nonpoint sources of nutrients for 1975-2004. Most of the data on nutrient concentrations (nitrate, ammonia, total nitrogen, orthophosphate, and total phosphorus) were from the U.S. Geological Survey's National Water Information System database (35.2 percent), the California Department of Water Resources (21.9 percent), the University of California at Davis (21.6 percent), and the U.S. Environmental Protection Agency's STOrage and RETrieval database (20.0 percent). Mar 28, 2011 Publication /pubs/HansonEtAl2010.pdf target="_blank" images/HansonEtAl.png Competition for water resources is growing throughout California, particularly in the Central Valley where about 20% of all groundwater used in the United States of America is consumed for agriculture and urban water supply. Continued agricultural use coupled with urban growth and potential climate change would result in continued depletion of groundwater storage and associated land subsidence throughout the Central Valley. For 1962-2003, an estimated 1230 hectametres (hm-cubed) of water was withdrawn from fine-grained beds, resulting in more than three metres (m) of additional land subsidence locally. Linked physically-based, supply-constrained and demand-driven hydrological models were used to simulate future hydrologic conditions under the A2 climate projection scenario that assumes continued "business as usual" greenhouse gas emissions. Results indicate an increased subsidence in the second half of the twenty-first century. Potential simulated land subsidence extends into urban areas and the eastern side of the valley where future surface-water deliveries may be depleted. Oct 22, 2010 Journal Article