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USGS2010

Groundwater-quality data for the Sierra Nevada study unit, 2008: Results from the California GAMA program

Groundwater quality in the approximately 25,500-square-mile Sierra Nevada study unit was investigated in June through October 2008, 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 U.S. Geological Survey (USGS) in cooperation with the California State Water Resources Control Board (SWRCB). The Sierra Nevada study was designed to provide statistically robust assessments of untreated groundwater quality within the primary aquifer systems in the study unit, and to facilitate statistically consistent comparisons of groundwater quality throughout California. The primary aquifer systems (hereinafter, primary aquifers) 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 public and community drinking-water supplies. The quality of groundwater in shallower or deeper water-bearing zones may differ from that in the primary aquifers; shallow groundwater may be more vulnerable to contamination from the surface. In the Sierra Nevada study unit, groundwater samples were collected from 84 wells (and springs) in Lassen, Plumas, Butte, Sierra, Yuba, Nevada, Placer, El Dorado, Amador, Alpine, Calaveras, Tuolumne, Madera, Mariposa, Fresno, Inyo, Tulare, and Kern Counties. The wells were selected on two overlapping networks by using a spatially-distributed, randomized, grid-based approach. The primary grid-well network consisted of 30 wells, one well per grid cell in the study unit, and was designed to provide statistical representation of groundwater quality throughout the entire study unit. The lithologic grid-well network is a secondary grid that consisted of the wells in the primary grid-well network plus 53 additional wells and was designed to provide statistical representation of groundwater quality in each of the four major lithologic units in the Sierra Nevada study unit: granitic, metamorphic, sedimentary, and volcanic rocks. One natural spring that is not used for drinking water was sampled for comparison with a nearby primary grid well in the same cell. Groundwater samples were analyzed for organic constituents (volatile organic compounds [VOC], pesticides and pesticide degradates, and pharmaceutical compounds), constituents of special interest (N-nitrosodimethylamine [NDMA] and perchlorate), naturally occurring inorganic constituents (nutrients, major ions, total dissolved solids, and trace elements), and radioactive constituents (radium isotopes, radon-222, gross alpha and gross beta particle activities, and uranium isotopes). Naturally occurring isotopes and geochemical tracers (stable isotopes of hydrogen and oxygen in water, stable isotopes of carbon, carbon-14, strontium isotopes, and tritium), and dissolved noble gases also were measured to help identify the sources and ages of the sampled groundwater. Three types of quality-control samples (blanks, replicates, and samples for matrix spikes) each were collected at approximately 10 percent of the wells sampled for each analysis, and the results for these samples were used to evaluate the quality of the data for the groundwater samples. Field blanks rarely contained detectable concentrations of any constituent, suggesting that contamination from sample collection, handling, and analytical procedures was not a significant source of bias in the data for the groundwater samples. Differences between replicate samples were within acceptable ranges, with few exceptions. Matrix-spike recoveries were within acceptable ranges for most compounds. This study did not attempt to evaluate the quality of water delivered to consumers; after withdrawal from the ground, groundwater typically is treated, disinfected, or blended with other waters to maintain water quality. Regulatory benchmarks apply to finished drinking water that is served to the consumer, not to untreated groundwater. However, to provide some context for the results, concentrations of constituents measured in the groundwater were compared with regulatory and nonregulatory health-based benchmarks established by the U.S. Environmental Protection Agency (USEPA) and CDPH and with nonregulatory aesthetic and technical benchmarks established by CDPH. Comparisons between data collected for this study and drinking-water benchmarks are for illustrative purposes only and do not indicate compliance or noncompliance with regulatory benchmarks. All organic constituents and most inorganic constituents that were detected in groundwater samples from the 30 primary grid wells in the Sierra Nevada study unit were detected at concentrations less than drinking-water benchmarks. Of the 150 organic and special-interest constituents analyzed, 21 were detected in groundwater samples; all concentrations were less than regulatory and nonregulatory health-based benchmarks, and most were less than 1/10th of benchmark levels. One or more organic constituents were detected in 37 percent of the primary grid wells, and perchlorate was detected in 27 percent of the primary grid wells. Most samples analyzed for inorganic and radioactive constituents had concentrations or activities less than regulatory and nonregulatory health-based benchmarks. Nutrients were not detected at concentrations greater than health-based benchmarks. Six of the 30 primary grid wells (20 percent) and 7 of the 53 lithologic grid wells had concentrations of or activities for one or two constituents that were greater than the benchmarks. Constituents present in one or more samples at concentrations or activities greater than health-based benchmarks were arsenic (5 wells, MCL-US), gross alpha particle activity (4 wells, MCL-US), boron (2 wells, NL-CA), fluoride (1 well, MCL-CA), and selenium (1 well, MCL-US). Two of the wells that had high gross alpha particle activities had uranium concentrations (MCL-CA) and uranium activities (MCL-CA) greater than the benchmark levels. Four of the 29 samples analyzed had activities of radon-222 greater than the proposed alternative MCL-US. Most samples analyzed for inorganic constituents that had nonregulatory, aesthetic-based benchmarks (SMCLs) had concentrations less than these benchmarks. Total dissolved solids concentrations were less than the upper SMCL-CA in all 83 primary and lithologic grid well samples, and TDS concentrations were less than the recommended SMCL-CA in 79 of these samples. Manganese concentrations were greater than the SMCL-CA in 2 of the 30 primary grid wells (7 percent) and in 6 of the 53 lithologic grid wells, and iron concentrations were greater than the SMCL-CA in the same 2 primary grid wells and in 5 of the same lithologic grid wells.

California↗
USGS2011

Assessment of selected contaminants in streambed- and suspended-sediment samples collected in Bexar County, Texas, 2007-09

Elevated concentrations of sediment-associated contaminants are typically associated with urban areas such as San Antonio, Texas, in Bexar County, the seventh most populous city in the United States. This report describes an assessment of selected sediment-associated contaminants in samples collected in Bexar County from sites on the following streams: Medio Creek, Medina River, Elm Creek, Martinez Creek, Chupaderas Creek, Leon Creek, Salado Creek, and San Antonio River. During 2007-09, the U.S. Geological Survey periodically collected surficial streambed-sediment samples during base flow and suspended-sediment (large-volume suspended-sediment) samples from selected streams during stormwater runoff. All sediment samples were analyzed for major and trace elements and for organic compounds including halogenated organic compounds and polycyclic aromatic hydrocarbons (PAHs). Selected contaminants in streambed and suspended sediments in watersheds of the eight major streams in Bexar County were assessed by using a variety of methods—observations of occurrence and distribution, comparison to sediment-quality guidelines and data from previous studies, statistical analyses, and source indicators. Trace elements concentrations were low compared to the consensus-based sediment-quality guidelines threshold effect concentration (TEC) and probable effect concentration (PEC). Trace element concentrations were greater than the TEC in 28 percent of the samples and greater than the PEC in 1.5 percent of the samples. Chromium concentrations exceeded sediment-quality guidelines more frequently than concentrations of any other constituents analyzed in this study (greater than the TEC in 69 percent of samples and greater than the PEC in 8 percent of samples). Mean trace element concentrations generally are lower in Bexar County samples compared to concentrations in samples collected during previous studies in the Austin and Fort Worth, Texas, areas, but considering the relatively large ranges and standard deviations associated with the concentrations measured in all three areas, the trace element concentrations are similar. On the basis of Mann-Whitney U test results, the presence of a military installation in a watershed was associated with statistically significant higher chromium, mercury, and zinc concentrations in streambed sediments compared to concentrations of the same elements in a watershed without a military installation. Halogenated organic compounds analyzed in sediment samples included pesticides (chlordane, dieldrin, DDT, DDD, and DDE), polychlorinated biphenyls (PCBs), and brominated flame retardants. Three or more halogenated organic compounds were detected in each sediment sample, and 66 percent of all concentrations were less than the respective interim reporting levels. Halogenated organic compound concentrations were mostly low compared to consensus-based sediment quality guidelines-;TECs were exceeded in 11 percent of the analyses and PECs were exceeded in 1 percent of the analyses. Chlordane compounds were the most frequently detected halogenated organic compounds with one or more detections of chlordane compounds in every watershed; concentrations were greater than the TEC in 6 percent of the samples. Dieldrin was detected in 50 percent of all samples, however all concentrations were much less than the TEC. The DDT compounds (p,p'-DDT, p,p'-DDD, and p,p'-DDE) were detected less frequently than some other halogenated organic compounds, however most detections exceeded the TECs. p,p'-DDT was detected in 13 percent of the samples (TEC exceeded in 67 percent); p,p'-DDD was detected in 19 percent of the samples (TEC exceeded in 78 percent); and p,p'-DDE was detected in 35 percent of the samples (TEC exceeded in 53 percent). p,p'-DDE concentrations in streambed-sediment samples correlate positively with population density and residential, commercial, and transportation land use. One or more PCB congeners were detected in

Texas↗
USGS2005

Evaluation of geohydrologic framework, recharge estimates and ground-water flow of the Joshua Tree area, San Bernardino County, California

Ground water historically has been the sole source of water supply for the community of Joshua Tree in the Joshua Tree ground-water subbasin of the Morongo ground-water basin in the southern Mojave Desert. The Joshua Basin Water District (JBWD) supplies water to the community from the underlying Joshua Tree ground-water subbasin. The JBWD is concerned with the long-term sustainability of the underlying aquifer. To help meet future demands, the JBWD plans to construct production wells in the adjacent Copper Mountain ground-water subbasin. As growth continues in the desert, there may be a need to import water to supplement the available ground-water resources. In order to manage the ground-water resources and to identify future mitigating measures, a thorough understanding of the ground-water system is needed. The purpose of this study was threefold: (1) improve the understanding of the geohydrologic framework of the Joshua Tree and Copper Mountain ground-water subbasins, (2) determine the distribution and quantity of recharge using field and numerical techniques, and (3) develop a ground-water flow model that can be used to help manage the water resources of the region. The geohydrologic framework was refined by collecting and interpreting water-level and water-quality data, geologic and electric logs, and gravity data. The water-bearing deposits in the Joshua Tree and Copper Mountain ground-water subbasins are Quarternary alluvial deposits and Tertiary sedimentary and volcanic deposits. The Quarternary alluvial deposits were divided into two aquifers (referred to as the 'upper' and the 'middle' alluvial aquifers), which are about 600 feet (ft) thick, and the Tertiary sedimentary and volcanic deposits were assigned to a single aquifer (referred to as the 'lower' aquifer), which is as thick as 1,500 ft. The ground-water quality of the Joshua Tree and Copper Mountain ground-water subbasins was defined by collecting 53 ground-water samples from 15 wells (10 in the Joshua Tree ground-water subbasin and 5 in the Copper Mountain ground-water subbasin) between 1980 and 2002 and analyzing the samples for major ions, nutrients, and selected trace elements. Selected samples also were analyzed for oxygen-18, deuterium, tritium, and carbon-14. The water-quality data indicated that dissolved solids and nitrate concentrations were below regulatory limits for potable water; however, fluoride concentrations in the lower aquifer exceeded regulatory limits. Arsenic concentrations and chromium concentrations were generally below regulatory limits; however, arsenic concentrations measured in water from wells perforated in the lower aquifer exceeded regulatory limits. The carbon-14 activities ranged from 2 to 72 percent modern carbon and are consistent with uncorrected ground-water ages (time since recharge) of about 32,300 to 2,700 years before present. The oxygen-18 and deuterium composition of water sampled from the upper aquifer is similar to the volume-weighted composition of present-day winter precipitation indicating that winter precipitation was the predominant source of ground-water recharge. Field studies, conducted during water years 2001 through 2003 to determine the distribution and quantity of recharge, included installation of instrumented boreholes in selected washes and at a nearby control site. Core material and cuttings from the boreholes were analyzed for physical, chemical, and hydraulic properties. Instruments installed in the boreholes were monitored to measure changes in matric potential and temperature. Borehole data were supplemented with temperature data collected from access tubes installed at additional sites along study washes. Streambed hydraulic properties and the response of instruments to infiltration were measured using infiltrometers. Physical and geochemical data collected away from the stream channels show that direct infiltration of precipitation to depths below the root zone and subsequent gro

Scientific Investigations Report↗
USGS2017

Groundwater resources of the Devils Postpile National Monument—Current conditions and future vulnerabilities

This study presents an extensive database on groundwater conditions in and around Devils Postpile National Monument. The database contains chemical analyses of springs and the monument water-supply well, including major-ion chemistry, trace element chemistry, and the first information on a list of organic compounds known as emerging contaminants. Diurnal, seasonal, and annual variations in groundwater discharge and chemistry are evaluated from data collected at five main monitoring sites, where streams carry the aggregate flow from entire groups of springs. These springs drain the Mammoth Mountain area and, during the fall months, contribute a significant fraction of the San Joaquin River flow within the monument. The period of this study, from fall 2012 to fall 2015, includes some of the driest years on record, though the seasonal variability observed in 2013 might have been near normal. The spring-fed streams generally flowed at rates well below those observed during a sequence of wet years in the late 1990s. However, persistence of flow and reasonably stable water chemistry through the recent dry years are indicative of a sizeable groundwater system that should provide a reliable resource during similar droughts in the future. Only a few emerging contaminants were detected at trace levels below 1 microgram per liter (μg/L), suggesting that local human visitation is not degrading groundwater quality. No indication of salt from the ski area on the north side of Mammoth Mountain could be found in any of the groundwaters. Chemical data instead show that natural mineral water, such as that discharged from local soda springs, is the main source of anomalous chloride in the monument supply well and in the San Joaquin River. The results of the study are used to develop a set of recommendations for future monitoring to enable detection of deleterious impacts to groundwater quality and quantity

California↗
USGS2002

Ground-water quality in the central High Plains aquifer, Colorado, Kansas, New Mexico, Oklahoma, and Texas, 1999

A network of 74 randomly distributed domestic water-supply wells completed in the central High Plains aquifer was sampled and analyzed from April to August 1999 as part of the High Plains Regional Ground-Water Study conducted by the U. S. Geological Survey National Water-Quality Assessment Program to provide a broad-scale assessment of the ground-water-quality in this part of the High Plains aquifer. Water properties were relatively consistent across the aquifer, with water being alkaline and well oxidized. Water was mostly of the calcium and magnesium-bicarbonate type and very hard. Sulfate concentrations in water from three wells and chloride concentration in water from one well exceeded Secondary Maximum Contaminant Levels. Fluoride concentration was equal to the Maximum Contaminant Level in one sample. Nitrate concentrations was relatively small in most samples, with the median concentration of 2.3 milligrams per liter. Dissolved organic carbon concentration was relatively low, with a median concentration of 0.5 milligram per liter. The Maximum Contaminant Level set by the U.S. Environmental Protection Agency for nitrate as nitrogen of 10 milligrams per liter was exceeded by water samples from three wells. Most samples contained detectable concentrations of the trace elements aluminum, arsenic, barium, chromium, molybdenum, selenium, zinc, and uranium. Only a few samples had trace element concentrations exceeding Maximum Contaminant Levels. Fifty-five of the samples had radon concentrations exceeding the proposed Maximum Contaminant Level of 300 picocuries per liter. The greatest radon concentrations were detected where the Ogallala Formation overlies sandstones, shales and limestones of Triassic, Jurassic, or Cretaceous age. Volatile organic compounds were detected in 9 of 74 samples. Toluene was detected in eight of those nine samples. All volatile organic compound concentrations were substantially less than Maximum Contaminant Levels. Detections of toluene may have been artifacts of the sampling and analytical processes. Pesticides were detected in 18 of the 74 water samples. None of the pesticide concentrations exceeded Maximum Contaminant Levels. The most frequently detected pesticides were atrazine and its metabolite deethylatrazine, which were detected in water from 15 and 17 wells, respectively. Most of the samples with a detectable pesticide had at least two detectable pesticides. Six of the samples had more than two detectable pesticides. Tritium concentrations was greater than 0.5 tritium unit in 10 of 51 samples, indicating recent recharge to the aquifer. Twenty-one of the samples that had nitrate concentrations greater than 4.0 milligrams per liter were assumed to have components of recent recharge. Detection of volatile organic compounds was not associated with those indicators of recent recharge, with most of volatile organic compounds being detected in water from wells with small tritium and nitrate concentrations. Detection of pesticides was associated with greater tritium or nitrate concentrations, with 16 of the 18 wells producing water with pesticides also having tritium or nitrate concentrations indicating recent recharge.

Colorado, Kansas, New Mexico, Oklahoma, Texas↗
USGS2001

Ground-water quality in Quaternary deposits of the central High Plains aquifer, south-central Kansas, 1999

Water samples from 20 randomly selected domestic water-supply wells completed in the Quaternary deposits of south-central Kansas were collected as part of the High Plains Regional Ground-Water Study conducted by the U.S. Geological Survey's National Water-Quality Assessment Program. The samples were analyzed for about 170 water-quality constituents that included physical properties, dissolved solids and major ions, nutrients and dissolved organic carbon, trace elements, pesticides, volatile organic compounds, and radon. The purpose of this study was to provide a broad overview of ground-water quality in a major geologic subunit of the High Plains aquifer. Water from five wells (25 percent) exceeded the 500-milligrams-per-liter of dissolved solids Secondary Maximum Contaminant Level for drinking water. The Secondary Maximum Contaminant Levels of 250 milligrams per liter for chloride and sulfate were exceeded in water from one well each. The source of these dissolved solids was probably natural processes. Concentrations of most nutrients in water from the sampled wells were small, with the exception of nitrate. Water from 15 percent of the sampled wells had concentrations of nitrate greater than the 10-milligram-per-liter Maximum Contaminant Level for drinking water. Water from 80 percent of the sampled wells showed nitrate enrichment (concentrations greater than 2.0 milligrams per liter), which is more than what might be expected for natural background concentrations. This enrichment may be the result of synthetic fertilizer applications, the addition of soil amendment (manure) on cropland, or livestock production. Most trace elements in water from the sampled wells were detected only in small concentrations, and few exceeded respective water-quality standards. Only arsenic was detected in one well sample at a concentration (240 micrograms per liter) that exceeded its proposed Maximum Contaminant Level (5.0 micrograms per liter). Additionally, one concentration of iron and two concentrations of manganese were larger than the Secondary Maximum Contaminant Levels of 300 and 50 micrograms per liter, respectively. Some occurrences of trace elements may have originated from human-related sources; however, the generally small concentrations that were measured probably reflect mostly natural sources for these constituents. A total of 47 pesticide compounds from several classes of herbicides and insecticides that included triazine, organophosphorus, organochlorine, and carbamate compounds and three pesticide degradation products were analyzed in ground-water samples during this study. Water from 50 percent of the wells sampled had detectable concentrations of one or more of these 47 compounds. The herbicide atrazine and its degradation product deethylatrazine were detected most frequently (in water from eight and nine wells, respectively); other pesticides detected were the insecticides carbofuran (in water from one well) and diazinon (in water from one well), and the herbicide metolachlor (in water from two wells). However, all concentrations of these compounds were small and substantially less than established Maximum Contaminant Levels. The use of pesticides in crop production probably is largely responsible for the occurrence of pesticides in the ground-water samples collected during this study. Although concentrations of detected pesticides were small (relative to established Maximum Contaminant Levels), the synergistic effect of these concentrations and long-term exposure to multiple pesticides on human health are unknown. Water samples from the Quaternary deposits were analyzed for 85 volatile organic compounds. Water from two wells (10 percent) had a detectable concentration of a volatile organic compound. Chloroform was detected at concen-trations of 0.18 and 0.25 microgram per liter, substantially less than the 100-microgram-per-liter Maximum Contaminant Level for total trihalomethanes. In general, the occurrence and detectio

Kansas↗
USGS2003

Review of Selected References and Data sets on Ambient Ground- and Surface-Water Quality in the Metedeconk River, Toms River, and Kettle Creek Basins, New Jersey, 1980-2001

Surface water and ground water from unconfined aquifers are the primary sources of drinking water for much of the population, about 391,000, in the Metedeconk River, Toms River, and Kettle Creek watersheds in the New Jersey Coastal Plain. The quality of these sources of drinking water is a concern because they are vulnerable to contamination. Indications of the occurrence, distribution, and likely sources and transport mechanisms of certain contaminants were obtained from 48 selected reports and 2 selected data sets on water quality in or near the watersheds (1980-2001). These indications are described and briefly summarized in this report. The findings of studies on ground-water quality indicate that shallow ground water within the study area generally meets primary drinking-water standards, with notable exceptions. Volatile organic compounds, mercury, arsenic, radionuclides, nitrate, and coliform bacteria have been detected in shallow ground water in some areas at levels that exceed Federal and State drinking-water standards. For example, results of analyses of untreated samples collected from more than 13,000 private wells during 1983-99 indicated that concentrations of volatile organic compounds in samples from 7.3 percent of the wells exceeded at least 1 of 11 drinking-water standards, according to records maintained by the Ocean County Health Department. In cases of exceedances, however, water treatment, well replacement, and (or) retesting assured that applicable drinking-water standards were being met at the tap. Reported concentrations of the pesticide chlordane in some areas exceeded the drinking-water standard; few data are available on the occurrence of other pesticides. Studies of nearby areas, however, indicate that pesticide concentrations generally could be expected to be below drinking-water standards. The combination of low pH and low dissolved solids in many areas results in shallow ground water that is highly corrosive and, if untreated, able to leach trace elements and release asbestos fibers from plumbing materials. Reported concentrations of nitrate, volatile organic compounds, trace elements, and pesticides in samples from the monitored mainstem and tributary streams within the study area generally are below maximum contaminant levels for drinking water or below detection limits. Results of studies in other areas indicate that pesticide concentrations in surface water could be considerably higher during high flows soon after the application of pesticides to crops than during low flows. Fecal coliform bacteria counts in streams vary considerably. Concentrations or counts of these classes of surface-water-quality constituents likely are functions of the intensity and type of upstream development. Results of limited monitoring for radionuclide concentrations reported by the Brick Township Municipal Utilities Authority of the Metedeconk River indicate that radionuclide concentrations or activities do not exceed maximum contaminant levels for drinking water. As a consequence of organic matter in surface water, the formati ultraviolet absorbance in samples from the Metedeconk River and the Toms River exceeded the alternative compliance criteria for source water (2.0 milligrams per liter for total organic carbon and 0.02 absorbance units-liters per milligram-centimeter for specific ultraviolet absorbance) with respect to treatment requirements for preventing elevated concentrations of disinfection by-products in treated water. Water-quality and treatment issues associated with use of ground and surface water for potable supply in the study area are related to human activities and naturally occurring factors. Additional monitoring and analysis of ground and surface water would be needed to determine conclusively the occurrence and distribution of some contaminants and the relative importance of various potential contaminant sources, transport and attenuation mechanisms, and transport pathways.

Water-Resources Investigations Report↗
USGS2002

Water quality and geochemical modeling of water at an abandoned coal mine reclaimed With coal combustion by-products

An abandoned coal mine in eastern Ohio was reclaimed with 125 tons per acre of pressurized fluidized bed combustion (PFBC) by-product. Water quality at the site (known as the Fleming site) was monitored for 7 years after reclamation; samples included water from soil-suction lysimeters (interstitial water), wells, and spring sites established downgradient of the application area. This report presents a summary of data collected at the Fleming site during the period September 1994 through June 2001. Additionally, results of geochemical modeling are included in this report to evaluate the potential fate of elements derived from the PFBC by-product. Chemical analyses of samples of interstitial waters within the PFBC by-product application area indicated elevated levels of pH and specific conductance and elevated concentrations of boron, calcium, chloride, fluoride, magnesium, potassium, strontium, and sulfate compared to water samples collected in a control area where traditional reclamation methods were used. Magnesium-to-calcium (Mg:Ca) mole ratios and sulfur-isotope ratios were used to trace the PFBC by-product leachate and showed that little, if any, leachate reached ground water. Concentrations of most constituents in interstitial waters in the application-area decreased during the seven sampling rounds and approached background concentrations observed in the control area; however, median pH in the application area remained above 6, indicating that some acid-neutralizing capacity was still present. Although notable changes in water quality were observed in interstitial waters during the study period, quality of ground water and spring water remained poor. Water from the Fleming site was not potable, given exceedances of primary and secondary Maximum Contaminant Levels (MCLs) for inorganic constituents in drinking water set by the U.S. Environmental Protection Agency. Only fluoride and sulfate, which were found in higher concentrations in application-area interstitial waters than in control-area interstitial waters, could be related to the PFBC by-product. Concentrations of arsenic, lead, and selenium typically were at or below the detection limits (generally 1 or 2 micrograms per liter). Elements detected at elevated concentrations in PFBC by-product application-area interstitial waters were not evident in downgradient ground water or spring water. Dilution of leachate by ground water was confirmed with a mixing model generated by the computer code NETPATH. Additionally, thermodynamic modeling of the chemical composition of water samples by use of the computer code PHREEQC indicated favorable conditions for precipitation of secondary minerals in the unsaturated zone and in aquifer materials. Because of low application rates of PFBC by-product and precipitation and sorption of elements in the unsaturated zone, it is improbable that concentrations of any toxic elements of concern (arsenic, lead, or selenium) will exceed drinking-water standards at this site or other sites where similar volumes of PFBC by-products are used.

Water-Resources Investigations Report↗
USGS2004

Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001

The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to urbanization; 47 of the 56 lakes are in or near one of 20 U.S. cities. Sampling was done with gravity, piston, and box corers from boats and push cores from boats or by wading, depending on the depth of water and thickness of sediment being sampled. Chemical analyses included major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, cesium-137, and lead-210. Age-dating of the cores was done on the basis of radionuclide analyses and the position of the pre-reservoir land surface in the reservoir and, in a few cases, other chemical or lithologic depth-date markers. Dates were assigned in many cores on the basis of assumed constant mass accumulation between known depth-date markers. Dates assigned were supported using a variety of other date markers including first occurrence and peak concentrations of DDT and polychlorinated biphenyls and peak concentration of lead. A qualitative rating was assigned to each core on the basis of professional judgment to indicate the reliability of age assignments. A total of 122 cores were collected from the 56 lakes and age dates were assigned to 113 of them, representing 54 of the 56 lakes. Seventy-four of the 122 cores (61 percent) received a good rating for the assigned age dates, 28 cores (23 percent) a fair rating, and 11 cores (9 percent) a poor rating; nine cores (7 percent) had no dates assigned. An analysis of the influence of environmental factors on the apparent quality of age-dating of the cores concluded that the most important factor was the mass accumulation rate (MAR) of sediment: the greater the MAR, the better the temporal discretization in the samples and the less important the effects of postdepositional sediment disturbance. These age-dated sediment cores provide the basis for local-, regional-, and national-scale interpretations of water-quality trends.

Alabama, Alaska, Arizona, California, Colorado, Fl↗
USGS2015

Water-quality characteristics and trends for selected wells possibly influenced by wastewater disposal at the Idaho National Laboratory, Idaho, 1981-2012

The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, analyzed water-quality data collected from 64 aquifer wells and 35 perched groundwater wells at the Idaho National Laboratory (INL) from 1981 through 2012. The wells selected for the study were wells that possibly were affected by wastewater disposal at the INL. The data analyzed included tritium, strontium-90, major cations, anions, nutrients, trace elements, total organic carbon, and volatile organic compounds. The analyses were performed to examine water-quality trends that might influence future management decisions about the number of wells to sample at the INL and the type of constituents to monitor. The data were processed using custom computer scripts developed in the R programming language. Summary statistics were calculated for the datasets. Water-quality trends were determined using a parametric survival regression model to fit the observed data, including left-censored, interval-censored, and uncensored data. The null hypothesis of the trend test was that no relation existed between time and concentration; the alternate hypothesis was that time and concentration were related through the regression equation. A significance level of 0.05 was selected to determine if the trend was statistically significant. Trend test results for tritium and strontium-90 concentrations in aquifer wells indicated that nearly all wells had decreasing or no trends. Similarly, trends in perched groundwater wells were mostly decreasing or no trends; trends were increasing in two perched groundwater wells near the Advanced Test Reactor Complex. Decreasing trends generally are attributed to lack of recent wastewater disposal and radioactive decay. Trend test results for chloride, sodium, sulfate, nitrite plus nitrate (as nitrogen), chromium, trace elements, and total organic carbon concentrations in aquifer wells indicated that most wells had either decreasing or no trends. The decreasing trends in these constituents are attributed to decrease in disposal of these constituents, as well as discontinued use of the old percolation ponds south of the Idaho Nuclear Technology and Engineering Center (INTEC) and redirection of wastewater to the new percolation ponds 2 miles southwest of the INTEC in 2002. Chloride (along with sodium, sulfate, and some nitrate) concentrations in wells south of the INTEC may be influenced by episodic recharge from the Big Lost River. These constituent concentrations decrease during wetter periods when there is probably more recharge from the Big Lost River and increase during dry periods, when there is less recharge. Some wells downgradient of the Central Facilities Area and near the southern boundary of the INL showed increasing trends in sodium concentration, whereas there was no trend in chloride. The increasing trend for sodium could be due to the long term influence of wastewater disposal from upgradient facilities and the lack of trend for chloride could be because chloride is more mobile than sodium and more dispersed in the aquifer system. Volatile organic compound concentration trends were analyzed for nine aquifer wells. Trend test results indicated an increasing trend for carbon tetrachloride for the Radioactive Waste Management Complex Production Well for the period 1987–2012; however, trend analyses of data collected since 2005 show no statistically significant trend indicating that engineering practices designed to reduce movement of volatile organic compounds to the aquifer may be having a positive effect on the aquifer.

Idaho↗
USGS1994

Ground-water quality and geochemistry in Dayton, Stagecoach, and Churchill Valleys, western Nevada

The U.S. Geological Survey investigated the quality of ground water in the Dayton, Stagecoach, and Churchill Valleys as part of the Carson River Basin National Water-Quality Assessment (NAWQA) pilot study. Four aquifer systems have been de- lineated in the study area. Principal aquifers are unconsolidated deposits at altitudes of less than 4,900 feet above sea level and more than 50 feet below land surface. Shallow aquifers are at altitudes of less than 4,900 feet and less than 50 feet below land surface. Upland aquifers are above 4,900 feet and provide recharge to the principal aquifers. Thermal aquifers, defined as those having a water temperature greater than 30 degrees Celsius, are also present. Ground water used in Dayton, Stagecoach, and Churchill Valleys is pumped from principal aquifers in unconsolidated basin-fill deposits. Ground water in these aquifers originates as precipitation in the adjacent mountains and is recharged by the Carson River and by underflow from adjacent upstream valleys. Ground-water flow is generally parallel to the direction of surface-water flow in the Carson River. Ground water is discharged by pumping, evapo- transpiration, and underflow into the Carson River. The results of geochemical modeling indicate that as ground water moves from upland aquifers in mountainous recharge areas to principal aquifers in basin-fill deposits, the following processes probably occur: (1) plagioclase feldspar, sodium chloride, gypsum (or pyrite), potassium feldspar, and biotite dissolve; (2) calcite precipitates; (3) kaolinite forms; (4) small amounts of calcium and magnesium in the water exchange for potassium on aquifer minerals; and (5) carbon dioxide is gained or lost. The geochemical models are consistent with (1) phases identified in basin- fill sediments; (2) chemical activity of major cations and silica; (3) saturation indices of calcite and amorphous silica; (4) phase relations for aluminosilicate minerals indicated by activity diagrams; and (5) results of optical, X-ray diffraction, and scanning-electron microscopy examination of mineral grains in the aquifer sediments. Sulfur-isotopic composition of ground- water samples also supports the models. In general, the quality of ground water in the study area meets Nevada State drinking-water standards and is acceptable for most uses. In addition to analysis for major ions, samples were analyzed for 22 inorganic trace elements, 3 nutrients, and 4 radionuclides. Selenium in 1 sample is the only constituent that exceeded Nevada State primary drinking-water standards. Nevada State secondary- drinking water standards were exceeded for fluoride in 1 sample, for iron in 7 samples, and for manganese in 19 samples. Minor constituent con- centrations are generally the result of local redox conditions, and are primarily from minerals in volcanic and marine metasedimentary rocks, metal- oxide coatings on mineral grains, and organic matter.

Open-File Report↗
USGS2011

Relations between hydrology, water quality, and taste-and-odor causing organisms and compounds in Lake Houston, Texas, April 2006-September 2008

Lake Houston is a surface-water-supply reservoir and an important recreational resource for the city of Houston, Texas. Growing concerns over water quality in Lake Houston prompted a detailed assessment of water quality in the reservoir. The assessment focused on water-quality constituents that affect the aesthetic quality of drinking water. The hydrologic and water-quality conditions influencing the occurrence of taste-and-odor causing organisms and compounds in Lake Houston were assessed using discrete and continuously monitored water-quality data collected during April 2006– September 2008. The hydrology of Lake Houston is characterized by rapidly changing conditions. During inflow events, water residence time can change by orders of magnitude within a matter of hours. Likewise, the reservoir can stratify and destratify over a period of several hours, even during non-summer and at relatively short water residence times, given extended periods with warm temperatures and little wind. The rapidly changing hydrology likely influences all other aspects of water quality in Lake Houston, including the occurrence of taste-and-odor causing organisms and compounds. Water quality in Lake Houston varied with respect to season and water residence time but typically was indicative of turbid, eutrophic to hypereutrophic conditions. In general, turbidity and nutrient concentrations were largest during non-summer (October–May) and when water residence times were relatively short (less than 100 days), which reflects the influence of inflow events on water-quality conditions. Large inflow events can cause substantial changes in water-quality conditions over relatively short periods of time (hours). The taste-and-odor causing organisms cyanobacteria and actinomycetes bacteria were always present in Lake Houston. Cyanobacterial biovolume was largest during summer (June– September) and when water residence time was greater than 100 days. Annual maxima in cyanobacterial biovolume occurred during July-September of each year, when temperatures were larger than 27 degrees Celsius and water residence times were longer than 400 days. In contrast, actinomycetes bacteria were most abundant during non-summer and when water residence times were less than 100 days, reflecting the close association between these organisms and transport of suspended sediments. Geosmin and 2-methylisoborneol are the taste-and-odor causing compounds most commonly produced by cyanobacteria and actinomycetes bacteria. Geosmin was detected more frequently (62 percent of samples) than 2-methylisoborneol (29 percent of samples) in Lake Houston. Geosmin exceeded the human detection threshold (10 nanograms per liter) only once during the study period and 2-methylisoborneol exceeded the human detection threshold twice. Manganese is a naturally occurring trace element that can occasionally cause taste-andodor problems in drinking water. Manganese concentrations exceeded the human detection threshold (about 50 micrograms per liter) in about 50 percent of samples collected near the surface and 84 percent of samples collected near the bottom. The cyanotoxin microcystin was detected relatively infrequently (16 percent of samples) and at small concentrations (less than or equal to 0.2 micrograms per liter). The abundance of the taste-and-odor causing organisms cyanobacteria and actinomycetes bacteria in Lake Houston was coupled with inflow events and subsequent changes in water-quality conditions. Cyanobacterial biovolume (biomass) in Lake Houston was largest during warm periods with little inflow and relatively small turbidity values. In contrast, actinomycetes bacteria were most abundant following inflow events when turbidity was relatively large. Severe taste-and-odor problems were not observed during the study period, precluding quantification of the hydrologic and water-quality conditions associated with large concentrations of taste-and-odor causing compounds and development of predictive models. Reservoir inflow (water residence time) and turbidity, variables related to the abundance of potential taste-andodor causing organisms, are currently (2011) continuously measured in Lake Houston, and predictive models could be developed in the future when the hydrologic and water-quality conditions associated with taste-and-odor problems have been better quantified. Seasonal and water residence time influences on water-quality conditions altered relations between hydrologic and water-quality conditions and taste-and-odor causing organisms and compounds. Future data collection and development of predictive models need to account for the variability associated with season and water residence time.

Texas↗
USGS2004

Water-quality data from 2002 to 2003 and analysis of data gaps for development of total maximum daily loads in the Lower Klamath River Basin, California

The U.S. Geological Survey (USGS) collected water-quality data during 2002 and 2003 in the Lower Klamath River Basin, in northern California, to support studies of river conditions as they pertain to the viability of Chinook and Coho salmon and endangered suckers. To address the data needs of the North Coast Regional Water Quality Control Board for the development of Total Maximum Daily Loads (TMDLs), water temperature, dissolved oxygen, specific conductance, and pH were continuously monitored at sites on the Klamath, Trinity, Shasta, and Lost Rivers. Water-quality samples were collected and analyzed for selected nutrients, organic carbon, chlorophyll-a, pheophytin-a, and trace elements. Sediment oxygen demand was measured on the Shasta River. Results of analysis of the data collected were used to identify locations in the Lower Klamath River Basin and periods of time during 2002 and 2003 when river conditions were more likely to be detrimental to salmonid or sucker health because of occasional high water temperatures, low dissolved oxygen, and conditions that supported abundant populations of algae and aquatic plants. The results were also used to assess gaps in data by furthering the development of the conceptual model of water flow and quality in the Lower Klamath River Basin using available data and the current understanding of processes that affect water quality and by assessing needs for the develoment of mathematical models of the system. The most notable gap in information for the study area is in sufficient knowledge about the occurrence and productivity of algal communities. Other gaps in data include vertical water-quality profiles for the reservoirs in the study area, and in an adequate understanding of the chemical oxygen demands and the sediment oxygen demands in the rivers and of the influence of riparian shading on the rivers. Several mathematical models are discussed in this report for use in characterizing the river systems in the study area; also discussed are the specific data needed for the models, and the spatial and temporal data available as boundary conditions. The models will be useful for the future development of TMDLs for temperature, nutrients, and dissolved oxygen and for assessing the role of natural and anthropogenic sources of heat, oxygen-producing and -consuming substances, and nutrients in the Klamath, Shasta, and Lost Rivers.

Scientific Investigations Report↗
USGS2007

Water-Quality Characteristics of Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek, Grand Teton National Park, Wyoming, 2006

To address water-resource management objectives of the National Park Service in Grand Teton National Park, the U.S. Geological Survey in cooperation with the National Park Service has conducted water-quality sampling on streams in the Snake River headwaters area. A synoptic study of streams in the western part of the headwaters area was conducted during 2006. Sampling sites were located on Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek. Sampling events in June, July, August, and October were selected to characterize different hydrologic conditions and different recreational-use periods. Stream samples were collected and analyzed for field measurements, major-ion chemistry, nutrients, selected trace elements, pesticides, and suspended sediment. Water types of Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek were calcium bicarbonate. Dissolved-solids concentrations were dilute in Cottonwood Creek and Taggart Creek, which drain Precambrian-era rocks and materials derived from these rocks. Dissolved-solids concentrations ranged from 11 to 31 milligrams per liter for samples collected from Cottonwood Creek and Taggart Creek. Dissolved-solids concentrations ranged from 55 to 130 milligrams per liter for samples collected from Lake Creek and Granite Creek, which drain Precambrian-era rocks and Paleozoic-era rocks and materials derived from these rocks. Nutrient concentrations generally were small in samples collected from Cottonwood Creek, Taggart Creek, Lake Creek, and Granite Creek. Dissolved-nitrate concentrations were the largest in Taggart Creek. The Taggart Creek drainage basin has the largest percentage of barren land cover of the basins, and subsurface waters of talus slopes may contribute to dissolved-nitrate concentrations in Taggart Creek. Pesticide concentrations, trace-element concentrations, and suspended-sediment concentrations generally were less than laboratory reporting levels or were small for all samples. Water-quality characteristics of streams in the western part of the Snake River headwaters area were compared to water-quality characteristics of streams sampled in 2002 in the eastern part of the headwaters area. The median dissolved-solids concentration (55 milligrams per liter) for samples collected from western streams was smaller than the median dissolved-solids concentration (125 milligrams per liter) for samples collected from eastern streams. The small dissolved-solids concentrations in the western streams are a result of the large areas underlain by resistant Precambrian-era rocks that compose the Teton Range compared to the more erodable Mesozoic-era sedimentary rocks that compose the mountains in the eastern part of the headwaters area. The Teton Range also receives higher annual precipitation than the mountains in the east. The median total-nitrogen concentration (0.17 milligram per liter) in samples collected from streams in the western part of the Snake River headwaters area was larger than the median concentration (0.10 milligram per liter) for samples collected from streams in the eastern part of the headwaters area, in part because of larger dissolved-nitrate concentrations in samples from the western streams compared to the eastern streams. In contrast, total-phosphorus concentrations generally were larger for samples collected from eastern streams. Large total-phosphorus concentrations in the eastern streams were associated with large suspended-sediment concentrations. The source of the phosphorus and sediment probably is Mesozoic-era sedimentary rocks of marine origin that underlie parts of the eastern drainage basins.

Scientific Investigations Report↗
USGS2005

Streamflow and water-quality trends of the Rio Chama and Rio Grande, northern and central New Mexico, water years 1985 to 2002

The City of Albuquerque plans to divert San Juan-Chama Project water from the Rio Grande for potable water use. This report examines streamflow and water-quality trends in the Rio Chama and the Rio Grande for water years 1985 to 2002 following the implementation of reservoir storage agreements in northern and central New Mexico. Streamflow/water-quality stations used for this study include the Rio Grande stations of Taos, Otowi, San Felipe, and Albuquerque and the Rio Chama station of Chamita. Water years 1985 to 2002 were a period of larger than average precipitation and streamflow compared to the stations. historical averages. Annual precipitation and streamflow trended downward during the study period because of a drought during 1999 to 2002. Streamflow in the Rio Chama and Rio Grande was divided into three distinct seasonal periods that corresponded to natural and anthropogenic influences: fall/winter baseflow (November through February), snowmelt runoff (March through June), and the irrigation/monsoon (July through October) seasons. A calcium bicarbonate water type was evident at all study area stations on the Rio Chama and Rio Grande. Specific conductance increased downstream, but alkalinity and pH did not substantially change in the downstream direction. Nearly all nitrogen and phosphorous concentrations were less than 1 milligram per liter for all stations. Median trace-element concentrations and maximum radionuclide concentrations did not exceed drinking-water standards. Anthropogenic compounds were infrequently detected in the Rio Chama and Rio Grande, and concentrations did not exceed drinking-water standards. Water quality in the Rio Chama and Rio Grande varied spatially and temporally during water years 1985 to 2002. Specific conductance increased downstream in the Rio Grande during the fall/winter baseflow and snowmelt runoff seasons but was similar at the Taos, Otowi, and San Felipe stations during the irrigation/monsoon season. This similarity was a result of the release of stored water from Abiquiu Reservoir and Cochiti Lake, which masked the natural influences that increased specific conductance in the downstream direction during the other seasons. During all seasons, pH decreased and major ion concentrations remained stable at the Albuquerque station compared with the San Felipe station, but no single influence could be identified that caused these conditions. Manganese and uranium concentrations at the Otowi and San Felipe stations were largest during the fall/winter baseflow and smallest during the snowmelt runoff, indicating that ground-water inflows likely influenced these concentrations. Water-quality temporal trends were evaluated for selected constituents during the study period and during the individual seasons. Downward trends in major ion concentrations were similar in magnitude at the Taos and Otowi stations, indicating that an upstream influence and (or) the downward trend in annual precipitation was the main reason(s) for these trends. The stations most affected by reservoirs, Chamita and San Felipe, were the only stations at which downward trends in major ions were apparent for flow-adjusted concentrations but not for seasonally correlated low-adjusted concentrations, which indicates fewer seasonal differences at these stations due to reservoir operations.

Scientific Investigations Report↗
USGS1998

Analysis of ground-water-quality data of the Upper Colorado River basin, water years 1972-92

As part of the U.S. Geological Survey's National Water-Quality Assessment program, an analysis of the existing ground-water-quality data in the Upper Colorado River Basin study unit is necessary to provide information on the historic water-quality conditions. Analysis of the historical data provides information on the availability or lack of data and water-quality issues. The information gathered from the historical data will be used in the design of ground-water-quality studies in the basin. This report includes an analysis of the ground-water data (well and spring data) available for the Upper Colorado River Basin study unit from water years 1972 to 1992 for major cations and anions, metals and selected trace elements, and nutrients. The data used in the analysis of the ground-water quality in the Upper Colorado River Basin study unit were predominantly from the U.S. Geological Survey National Water Information System and the Colorado Department of Public Health and Environment data bases. A total of 212 sites representing alluvial aquifers and 187 sites representing bedrock aquifers were used in the analysis. The available data were not ideal for conducting a comprehensive basinwide water-quality assessment because of lack of sufficient geographical coverage. Evaluation of the ground-water data in the Upper Colorado River Basin study unit was based on the regional environmental setting, which describes the natural and human factors that can affect the water quality. In this report, the ground-water-quality information is evaluated on the basis of aquifers or potential aquifers (alluvial, Green River Formation, Mesaverde Group, Mancos Shale, Dakota Sandstone, Morrison Formation, Entrada Sandstone, Leadville Limestone, and Precambrian) and land-use classifications for alluvial aquifers. Most of the ground-water-quality data in the study unit were for major cations and anions and dissolved-solids concentrations. The aquifer with the highest median concentrations of major ions was the Mancos Shale. The U.S. Environmental Protection Agency secondary maximum contaminant level of 500 milligrams per liter for dissolved solids in drinking water was exceeded in about 75 percent of the samples from the Mancos Shale aquifer. The guideline by the Food and Agriculture Organization of the United States for irrigation water of 2,000 milligrams per liter was also exceeded by the median concentration from the Mancos Shale aquifer. For sulfate, the U.S. Environmental Protection Agency proposed maximum contaminant level of 500 milligrams per liter for drinking water was exceeded by the median concentration for the Mancos Shale aquifer. A total of 66 percent of the sites in the Mancos Shale aquifer exceeded the proposed maximum contaminant level. Metal and selected trace-element data were available for some sites, but most of these data also were below the detection limit. The median concentrations for iron for the selected aquifers and land-use classifications were below the U.S. Environmental Protection Agency secondary maximum contaminant level of 300 micrograms per liter in drinking water. Median concentration of manganese for the Mancos Shale exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 50 micrograms per liter in drinking water. The highest selenium concentrations were in the alluvial aquifer and were associated with rangeland. However, about 22 percent of the selenium values from the Mancos Shale exceeded the U.S. Environmental Protection Agency maximum contaminant level of 50 micrograms per liter in drinking water. Few nutrient data were available for the study unit. The only nutrient species presented in this report were nitrate-plus-nitrite as nitrogen and orthophosphate. Median concentrations for nitrate-plus-nitrite as nitrogen were below the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter in drinking water except for 0.02 percent of the sites in the alluvial aquifer and 0.03 percent of the sites in the Mancos Shale. Concentrations of orthophosphate did not vary significantly among aquifers or land-use classifications. Historic water-quality data from wells and springs helped to characterize the regional distribution of ground-water quality information in the Upper Colorado River Basin study unit. The historical ground-water data summarized in this report will be used in the design of a ground-water-quality network. Because ground-water-quality issues in the study unit are related to high dissolved solids, sulfate, selenium, and nutrients, this report discusses some of the important findings related to these issues.

Colorado↗
USGS2010

Water Quality in the Equus Beds Aquifer and the Little Arkansas River Before Implementation of Large-Scale Artificial Recharge, South-Central Kansas, 1995-2005

Artificial recharge of the Equus Beds aquifer using runoff from the Little Arkansas River in south-central Kansas was first proposed in 1956 and was one of many options considered by the city of Wichita to preserve its water supply. Declining aquifer water levels of as much as 50 feet exacerbated concerns about future water availability and enhanced migration of saltwater into the aquifer from past oil and gas activities near Burrton and from the Arkansas River. Because Wichita changed water-management strategies and decreased pumping from the Equus Beds aquifer in 1992, water storage in the aquifer recovered by about 50 percent. This recovery is the result of increased reliance on Cheney Reservoir for Wichita water supply, decreased aquifer pumping, and larger than normal precipitation. Accompanying the water-level recovery, the average water-level gradient in the aquifer decreased from about 12 feet per mile in 1992 to about 8 feet per mile in January 2006. An important component of artificial recharge is the water quality of the receiving aquifer and the water being recharged (source water). Water quality within the Little Arkansas River was defined using data from two real-time surface-water-quality sites and discrete samples. Water quality in the Equus Beds aquifer was defined using sample analyses collected at 38 index sites, each with a well completed in the shallow and deep parts of the Equus Beds aquifer. In addition, data were collected at diversion well sites, recharge sites, background wells, and prototype wells for the aquifer storage and recovery project. Samples were analyzed for major ions, nutrients, trace metals, radionuclides, organic compounds, and bacterial and viral indicators. Water-quality constituents of concern for artificial recharge are those constituents that frequently (more than 5 percent of samples) may exceed Federal [U.S. Environmental Protection Agency (USEPA)] and State drinking-water criteria in water samples from the receiving aquifer or in samples from the source water. Constituents of concern include major ions (sulfate and chloride), nutrients (nitrite plus nitrate), trace elements (arsenic, iron, and manganese), organic compounds (atrazine), and fecal bacterial indicators. This report describes the water quality in the Equus Beds aquifer and the Little Arkansas River from 1995 through 2005 before implementation of large-scale recharge activities. Sulfate concentrations in water samples from the Little Arkansas River rarely exceeded Federal secondary drinking water regulation (SDWR) of 250 milligrams per liter (mg/L). Sulfate concentrations in groundwater were exceeded in about 18 percent of the wells in the shallow (less than or equal to 80 feet deep) parts of the aquifer and in about 13 percent of the wells in the deep parts the aquifer. Larger sulfate concentrations were associated with parts of the aquifer with the largest water-level declines. Water-quality changes in the Equus Beds aquifer likely were caused by dewatering and oxidation of aquifer material that subsequently resulted in increased sulfate concentrations as water levels recovered. The primary sources of chloride to the Equus Beds aquifer are from past oil and gas activities near Burrton and from the Arkansas River. Computed chloride concentrations in the Little Arkansas River near Halstead exceeded the Federal SDWR of 250 mg/L about 27 percent of the time (primarily during low-flow conditions). Chloride concentrations in groundwater exceeded 250 mg/L in about 8 percent or less of the study area, primarily near Burrton and along the Arkansas River. Chloride in groundwater near Burrton has migrated downgradient about 3 miles during the past 40 to 45 years. The downward and horizontal migration of the chloride is controlled by the hydraulic gradient in the aquifer, dispersion of chloride, and discontinuous clay layers that can inhibit further downward migration. Chloride in the shallow parts of the Equus Beds

Scientific Investigations Report↗
USGS1994

A comparison of simultaneous plasma, atomic absorption, and iron colorimetric determinations of major and trace constituents in acid mine waters

Sixty-three water samples collected during June to October 1982 from the Leviathan/Bryant Creek drainage basin were originally analyzed by simultaneous multielement direct-current plasma (DCP) atomic-emission spectrometry, flame atomic-absorption spectrometry, graphite-furnace atomic-absorption spectrometry (GFAAS) (thallium only), ultraviolet-visible spectrometry, and hydride-generation atomic-absorption spectrometry.Determinations were made for the following metallic and semi-metallic constituents: AI, As, B, Ba, Be, Bi, Cd, Ca, Cr, Co, Cu, Fe(11), Fe(total), Li, Pb, Mg, Mn, Mo, Ni, K, Sb, Se, Si, Na, Sr, TI, V, and Zn. These samples were re-analyzed later by simultaneous multielement inductively coupled plasma (ICP) atomic-emission spectrometry and Zeeman-corrected GFAAS to determine the concentrations of many of the same constituents with improved accuracy, precision, and sensitivity. The result of this analysis has been the generation of comparative concentration values for a significant subset of the solute constituents. Many of the more recently determined values replace less-than-detection values for the trace metals; others constitute duplicate analyses for the major constituents. The multiple determinations have yielded a more complete, accurate, and precise set of analytical data. They also have resulted in an opportunity to compare the performance of the plasma-emission instruments operated in their respective simultaneous multielement modes. Flame atomic-absorption spectrometry was judged best for Na and K and hydride-generation atomic-absorption spectrometry was judged best for As because of their lower detection limit and relative freedom from interelement spectral effects. Colorimetric determination using ferrozine as the color agent was judged most accurate, precise, and sensitive for Fe. Cadmium, lead, and vanadium concentrations were too low in this set of samples to enable a determination of whether ICP or DCP is a more suitable technique. Of the remaining elements, Ba, Be, Ca, Cr, Mg, Mn, Sr, and Zn have roughly equivalent accuracy, precision, and detection limit by ICP and DCP. Cobalt and Ni were determined to be better analyzed by ICP, because of lower detection limits; B, Cu, Mo, and Si were determined to be better analyzed by DCP, because of relative freedom from interferences. The determination oral by DCP was far more sensitive, owing to the use of a more sensitive wavelength, compared with the ICP. However, there is a very serious potential interference from a strong Ca emission line near the 396.15 nanometer DCP wavelength. Thus, there is no clear choice between the plasma techniques tested, for the determination oral. The ICP and DCP detection limits are typically between 0.001 and 0.5 milligrams per liter in acid mine waters. For those metals best analyzed by ICP and/or DCP, but below these limits, GFAAS is the method of choice because of its relatively greater sensitivity and specificity. Six of the elements were not determined by DCP, ICP or Zeeman-corrected GFAAS, and are not discussed in this report. These elements are: Bi, Fe(11), Li, Sb, Se, and TI.

Water-Resources Investigations Report↗