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USGS1963

Geologic and hydrologic features of the San Bernardino area, California; with special reference to underflow across the San Jacinto fault

This is the second in a series of interpretive reports on subsurface outflow from the ground-water basins of San Bernardino County, Calif., prepared by the U.S. Geological Survey in cooperation with the San Bernardino County Flood Control District. One principal purpose of the study was to estimate the ground-water outflow from the Bunker Hill basin to the Rialto-Colton basin across the San Jacinto fault, which, except locally, forms a nearly impermeable boundary between the two basins. In addition, the report deals qualitatively with the geology, the fault barriers that divide the area into several ground-water basins, the physical nature and degree of imperviousness of the barriers, the occurrence and movement of ground water and fluctuations of water level in the basins, and the chemical quality of surface and ground waters in the San Bernardino area. The report includes a geologic map and sections, water-level-contour maps and profiles, and hydrographs of selected well. The Santa Ana River, the principal stream, flows generally westward across the area. Channels of the river and its tributaries overlie a large irregular structural depression filled with alluvial deposits ranging in age from late Tertiary to Recent and forming a valley bounded on the north by the San Gabriel Mountains, on the east by the San Bernardino Mountains, and on the south by an irregular group of hills. Large alluvial fans underlie most of the area, but its landforms also include alluvial benches and terraces near the mountains, stream channels, and elongate hills, ridges, and scarps along the trace of the San Jacinto fault, which strikes northwestward across the valley about in the center of the area. This fault and others divide the area into ground-water basins, which include the Bunker Hill, Rialto-Colton, upper and lower Lytle and Chino basins. The water-bearing deposits include the following units: the younger alluvium. of Recent age, which occupies principally the backfilled channels beneath the Santa Ana River and its tributaries and through which ground water moves from Bunker Hill basin to Rialto-Colton basin; the older alluvium, of Pleistocene age, which is the principal water-bearing unit of the area and yields water to more than a thousand wells; and continental deposits of Tertiary to Quaternary age, which crop out along the southern margin of the area and locally along the San Gabriel Mountains on the north. The younger alluvium attains a maximum thickness of about 125 feet beneath the Santa Ana River south of San Bernardino. Locally in the Bunker Hill basin it is composed of two members, an upper member of relatively impermeable clay and a lower member of highly permeable material in which water is confined by the upper member. The older alluvium locally has a known thickness greater than 700 feet; elsewhere in the San Bernardino Valley it may exceed 1,400 feet. Locally, where ground water is confined in Bunker Hill basin, the older alluvium is divided into three permeable water-bearing zones separated from each other and from the younger alluvium above by less permeable zones. In parts of Chino and Rialto-Colton basins the alluvium consists of a coarse-grained facies along a former course of a major stream that is interfingered with and overlain by relatively fine-grained deposits. The permeability of the younger alluvium in the area beneath the Santa Ana River downstream from the San Jacinto fault was determined from tests to be about 2,700 gallons per day per square foot. The permeability of the coarse water-yielding materials of the older alluvium several miles downstream was estimated from tests to be about the same magnitude. Rocks that yield practically no water include continental rocks of Tertiary age, which are not exposed in the area but are tapped by wells in Rialto-Colton basin, and crystalline and metamorphic rocks of pre-Tertiary age that form the bedrock of the area.

California↗

USGS2007

Water- and air-quality monitoring of the Sweetwater Reservoir Watershed, San Diego County, California-Phase One results, continued, 1999-2001

In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to assess the overall health of the Sweetwater watershed with respect to chemical contamination. The study included regular sampling of air and water at Sweetwater Reservoir for chemical contaminants, including volatile organic compounds, polycyclic aromatic hydrocarbons, pesticides, and major and trace elements. Background water samples were collected at Loveland Reservoir for volatile organic compounds and pesticides. The purpose of this study was to monitor changes in contaminant composition and concentration in the air and water resulting from the construction and operation of State Route 125 near Sweetwater Reservoir. To accomplish this, the study was divided into two phases. Phase One sampling was designed to establish baseline conditions for target compounds in terms of detection frequency and concentration in air and water. Phase Two sampling is planned to continue at the established monitoring sites during and after construction of State Route 125 to assess the chemical impact this roadway alignment project may have on the water quality in the reservoir. In addition to the ongoing data collection, several special studies were initiated to assess the occurrence of specific chemicals of concern, such as low-use pesticides, trace metals, and wastewater compounds. This report describes the study design, and the sampling and analytical methods, and presents the results for the second and third years of the study (October 1999 to September 2001). Data collected during the first year of sampling (October 1998 to September 1999) were published in 2002.

California↗

USGS2023

Fluid migration pathways to groundwater in mature oil fields: Exploring the roles of water injection/production and oil-well integrity in California, USA

Mature oil fields potentially contain multiple fluid migration pathways toward protected groundwater (total dissolved solids, TDS, in nonexempted aquifer <10,000 mg/L) because of their extensive development histories. Time-series data for water use, fluid pressures, oil-well construction, and geochemistry from the South Belridge and Lost Hills mature oil fields in California are used to explore the roles of injection/production of oil-field water and well-integrity issues in fluid migration. Injection/production of oil-field water modified hydraulic gradients in both oil fields, resulting in chemical transport from deeper groundwater and hydrocarbon-reservoir systems to aquifers in the oil fields. Those aquifers are used for water supply outside the oil-field boundaries. Oil wells drilled before 1976 can be fluid migration pathways because a relatively large percentage of them have >10 m of uncemented annulus that straddles oil-well casing damage and/or the base of groundwater with TDS <10,000 mg/L. The risk of groundwater-quality degradation is higher when wells with those risk factors occur in areas with upward hydraulic gradients created by positive net injection, groundwater withdrawals, or combinations of these variables. The complex changes in hydrologic conditions and groundwater chemistry likely would not have been discovered in the absence of years to decades of monitoring data for groundwater elevations and chemistry, and installation of monitoring wells in areas with overlapping risk factors. Important monitoring concepts based on results from this and other studies include monitoring hydrocarbon-reservoir and groundwater systems at multiple spatiotemporal scales and maintaining transparency and accessibility of data and analyses. This analysis focuses on two California oil fields, but the methods used and processes affecting fluid migration could be relevant in other oil fields where substantial injection/production of oil-field water occurs and oil-well integrity is of concern.

California↗

USGS2009

Characterization of rock samples and mineralogical controls on leachates

Rocks associated with coal beds typically include shale, sandstone, and (or) limestone. In addition to common rock-forming minerals, all of these rock types may contain sulfide and sulfate minerals, various carbonate minerals, and organic material. These different minerals have inherently different solubility characteristics, as well as different acid-generating or acid-neutralizing potentials. The abundance and composition of sulfur- and carbonate-bearing minerals are of particular interest in interpreting the leaching column data because (1) pyrite and carbonate minerals are the primary controls on the acid-base account of a sample, (2) these minerals incorporate trace metals that can be released during weathering, and (3) these minerals readily react during weathering due to mineral dissolution and oxidation of iron. Rock samples were collected by the Pennsylvania Department of Environmental Protection (PaDEP) from five different sites to assess the draft standardized leaching column method (ADTI-WP2) for the prediction of weathering rates and water quality at coal mines. Samples were sent to USGS laboratories for mineralogical characterization and to ActLabs for chemical analysis. The samples represent a variety of rock types (shales, sandstones, and coal refuse) that are typical of coal overburden in the eastern United States. These particular samples were chosen for testing the weathering protocols because they represent a range of geochemical and lithologic characteristics, sulfur contents, and acid-base accounting characteristics (Hornberger et al., 2003). The rocks contain variable amounts of pyrite and carbonate minerals and vary in texture. This chapter includes bulk rock chemical data and detailed mineralogical and textural data for unweathered starting materials used in the interlaboratory validation study, and for two samples used in the early phases of leaching column tests (Wadesville Sandstone, Leechburg Coal Refuse). We also characterize some of the post-weathering rock samples, report trace-element content in leachate, and discuss mineralogical controls on leachate quality based on data from one of the participating laboratories. Table 5.1 lists the samples described in this chapter, the sample numbers, and comments on the characteristics of each lithology. Sample locations are plotted in Figure 5.1. Chapters 2 and 3 describe the sample locations, sample preparation protocols, ABA characteristics, and rationale for selection of rock samples for testing. Microprobe data for pyrite and carbonate minerals are tabulated in Appendix 5.1. Leachate data, along with a series of graphs showing concentration and cumulative transport trends, for the laboratory data discussed in this chapter are included as Excel spreadsheets in Appendices 5.2 and 5.3. Leach column data for the interlaboratory study are evaluated and interpreted in Chapters 7 -11.

Arkansas, Florida, Georgia, Illinois, Indiana, Iow↗

USGS2011

Sediment toxicity test results for the Urban Waters Study 2010, Bellingham Bay, Washington

The Washington Department of Ecology annually determines the quality of recently deposited sediments in Puget Sound as a part of Ecology's Urban Waters Initiative. The annual sediment quality studies use the Sediment Quality Triad (SQT) approach, thus relying on measures of chemical contamination, toxicity, and benthic in-faunal effects (Chapman, 1990). Since 2002, the studies followed a rotating sampling scheme, each year sampling a different region of the greater Puget Sound Basin. During the annual studies, samples are collected in locations selected with a stratified-random design, patterned after the designs previously used in baseline surveys completed during 1997-1999 (Long and others, 2003; Wilson and Partridge, 2007). Sediment samples were collected by personnel from the Washington Department of Ecology, in June of 2010 and shipped to the U. S. Geological Survey (USGS) laboratory in Corpus Christi, Texas (not shown), where the tests were performed. Sediment pore water was extracted with a pneumatic apparatus and was stored frozen. Just before testing, water-quality measurements were made and salinity adjusted, if necessary. Tests were performed on a dilution series of each sample consisting of 100-, 50-, and 25-percent pore-water concentrations. The specific objectives of this study were to: * Extract sediment pore water from a total of 30 sediment samples from the Bellingham Bay, Washington area within a day of receipt of the samples. * Measure water-quality parameters (salinity, dissolved oxygen, pH, sulfide, and ammonia) of thawed pore-water samples before testing and adjust salinity, temperature and dissolved oxygen, if necessary, to obtain optimal ranges for the test species. * Conduct the fertilization toxicity test with pore water using sea urchin (Stronylocentrotus purpuratus) (S. purpuratus) gametes. * Perform quality control assays with reference pore water, dilution blanks and a positive control dilution series with sodium dodecyl sulfate (SDS) in conjunction with each test. * Determine which samples caused a significant decrease in percent fertilization success relative to the negative control.

Washington↗

USGS1992

Classifying and mapping wetlands and peat resources using digital cartography

Digital cartography allows the portrayal of spatial associations among diverse data types and is ideally suited for land use and resource analysis. We have developed methodology that uses digital cartography for the classification of wetlands and their associated peat resources and applied it to a 1:24 000 scale map area in New Hampshire. Classifying and mapping wetlands involves integrating the spatial distribution of wetlands types with depth variations in associated peat quality and character. A hierarchically structured classification that integrates the spatial distribution of variations in (1) vegetation, (2) soil type, (3) hydrology, (4) geologic aspects, and (5) peat characteristics has been developed and can be used to build digital cartographic files for resource and land use analysis. The first three parameters are the bases used by the National Wetlands Inventory to classify wetlands and deepwater habitats of the United States. The fourth parameter, geological aspects, includes slope, relief, depth of wetland (from surface to underlying rock or substrate), wetland stratigraphy, and the type and structure of solid and unconsolidated rock surrounding and underlying the wetland. The fifth parameter, peat characteristics, includes the subsurface variation in ash, acidity, moisture, heating value (Btu), sulfur content, and other chemical properties as shown in specimens obtained from core holes. These parameters can be shown as a series of map data overlays with tables that can be integrated for resource or land use analysis.

Conference Paper↗

USGS1983

Ground-water resources of the Rutland area, Vermont

Ground water in the Rutland area occurs both in the bedrock and the overlying unconsolidated glacial deposits. Bedrock in the area is composed of a series of metamorphic and igneous rocks. Water from wells drilled in bedrock can be obtained in sufficient quantities for domestic use nearly anywhere in the area. The median well yield for 4 different bedrock hydrogeologic units ranges from 2 to 7 gallons per minute. Unconsolidated deposits in the Rutland area include till, clay, sand, and gravel. Saturated sand and gravel capable of yielding more than 200 gallons per minute is found in the major valleys of the area. Chemical analyses of water from 72 wells indicate that 29 percent of these sources contain one or more constituents that exceed the limits recommended by the U.S. Environmental Protection Agency (1977, 1978) for public drinking water supplies. The most common problem constituents are iron and manganese. In addition, elevated levels of chloride and nitrate suggest that 65 percent of the sampled sources have some water-quality deterioration. (USGS)

Vermont↗

USGS2010

Water-quality, water-level, and discharge data associated with the Mississippi embayment agricultural chemical-transport study, 2006-2008

In 2006, the Agricultural Chemicals: Sources, Transport and Fate study team (Agricultural Chemicals Team, ACT) of the U.S. Geological Survey National Water-Quality Assessment Program began a study in northwestern Mississippi to evaluate the influence of surface-water recharge on the occurrence of agriculturally related nutrients and pesticides in the Mississippi River Valley alluvial aquifer. The ACT study was composed in the Bogue Phalia Basin, an indicator watershed within the National Water-Quality Assessment Program Mississippi Embayment Study Unit and utilized several small, subbasins within the Bogue Phalia to evaluate surface and groundwater interaction and chemical transport in the Basin. Data collected as part of this ACT study include water-quality data from routine and incident-driven water samples evaluated for major ions, nutrients, organic carbon, physical properties, and commonly used pesticides in the area; discharge, gage height and water-level data for surface-water sites, the shallow alluvial aquifer, and hyporheic zone; additionally, agricultural data and detailed management activities were reported by land managers for farms within two subbasins of the Bogue Phalia Basin—Tommie Bayou at Pace, MS, and an unnamed tributary to Clear Creek near Napanee, MS.

Mississippi↗

USGS2009

Selected Physical, Chemical, and Biological Data Used to Study Urbanizing Streams in Nine Metropolitan Areas of the United States, 1999-2004

This report documents and summarizes physical, chemical, and biological data collected during 1999-2004 in a study titled Effects of Urbanization on Stream Ecosystems, undertaken as part of the U.S. Geological Survey's National Water-Quality Assessment Program. Data-collection methods and data processing are described in this report for streamflow; stream temperature; instream chemistry; instream aquatic habitat; and algal, macroinvertebrate, and fish communities. Data summaries prepared for analytical use are presented in downloadable data tables.

Data Series↗

USGS2023

Achieving water quality goals in the Chesapeake Bay: A comprehensive evaluation of system response

A Comprehensive Evaluation of System Response Achieving Water Quality Goals in the Chesapeake Bay: A Comprehensive Evaluation of System Response (CESR) includes an evaluation of why progress toward meeting the TMDL and water quality standards has been slower than expected and offers options for how progress can be accelerated. This report is a summation of a three year investigation into the 40 year effort to reduce nutrient loads to Chesapeake Bay. History The effort began as a STAC independent initiative in March 2019, after Kurt Stephenson, Zach Easton, and Brian Benham proposed the idea of a report that would identify gaps and uncertainties in system response—physical, chemical, biological, and socioeconomic—that impact efforts designed to attain water quality standards in Chesapeake Bay. As STAC Chair at the time, Benham facilitated the development of a collaborative process that would engage the entire committee. As a first step in approaching the long causal chain that links management actions to their eventual impact on water quality and living resources, workgroups were formed around the subsystems of this chain: nutrient and sediment reductions (watershed), water quality response to nutrient and sediment reductions (estuary) and living resource response to water quality (living resources). Each of these workgroups generated an independent document with a self-determined scope (i.e., workgroups were afforded flexibility to address issues beyond the original objectives). Because the content of each document was both unique and substantial, STAC chose to publish them as stand-alone documents with authorship attribution. In the second step, a steering committee developed a series of framing questions to guide the preparation of this report that would meet the objective of identifying gaps and uncertainties in achieving the Bay TMDL and water quality standards. Coeditors Stephenson and Wardrop, supported to great extent by a subgroup of the Steering Committee (Leonard Shabman, Zach Easton, Jeremy Testa, William Dennison, Kenny Rose, and Mark Monaco) were tasked with assembling ideas and contributions to write a single draft text, drawing material from the aforementioned resource documents, STAC and Chesapeake Bay Program reports, the scientific literature, and a limited amount of additional analyses performed in collaboration with Bay Program scientists. The resulting report was then submitted for several reviews by both steering committee members and the membership at-large to produce a consensus report.

Maryland, Virginia↗

USGS2002

Hydrogeochemical investigations of historic mining districts, central western slope of Colorado, including influence on surface-water quality

This report describes reconnaissance hydrogeochemical investigations of 22 mining districts on the Western Slope of Colorado in the Gunnison and Uncompahgre National Forests and adjacent public lands administered by the Bureau of Land Management. Sources and fates of contaminants from historic mines, mine waste, and mill tailings are interpreted from chemical analyses for 190 samples of surface waters; 185 samples of mined rocks, mill tailings, and altered rocks; and passive leach analyses of 116 samples of those mineralized materials. Short reaches of several headwater streams show relatively low level effects of historic mining; the headwaters of the Uncompahgre River are highly contaminated by mines and unmined altered rocks in the Red Mountain district. There is encouraging evidence that natural processes attenuate mine-related contamination in most districts.

Colorado↗

USGS2020

Methods of collection and quality assessment of arsenic data in well-water supplies in Maine, 2001–2 and 2006–7

The U.S. Geological Survey, in cooperation with the U.S. Centers for Disease Control and Prevention and the Maine Center for Disease Control and Prevention, assessed the chemical characteristics and the occurrence, distribution, and oxidation state of inorganic arsenic in drinking water from selected domestic well-water supplies in Maine in 2001–2 and 2006–7. The data collected provide support for evaluating arsenic-removal efficiencies of household water-purification systems and provide information to State and local officials that can be used in determining a water-treatment approach for the removal of arsenic from drinking water.

Maine↗

USGS2018

Karst hydrogeology of Tuckaleechee Cove and the western Great Smoky Mountains, Tennessee and North Carolina

The geology of Great Smoky Mountains National Park (GRSM) in Tennessee and North Carolina is dominated by siliciclastics and metamorphic strata. However, in the western portion of GRSM, a series of carbonate fensters (windows) expose the Lower Ordovician–age section of the Knox Group, a series of dolomite and limestone units that are partially marbleized as a result of contact metamorphism from the Great Smoky fault. The fensters create opportunities for allogenic recharge to occur at points along the contact of the surrounding insoluble strata with the underlying soluble carbonates. The combination of chemically aggressive surface recharge and vertical relief has resulted in the formation of deep caves, many of which have active streams and water resources. Though the karst is limited in extent and the number of caves is fairly small, the significance of the resources is substantial, with several of the caves in the area over 150 m in depth and at least two being major bat hibernacula. In 2017, the U.S. Geological Survey (USGS) began a study to better understand the hydrologic behavior of these karst systems through hydrologic and geochemical monitoring, groundwater tracing using fluorescent dyes, and seepage runs. Stage and water-quality instrumentation was installed in two caves in GRSM, the main stream of Bull Cave, and in a sump pool in Whiteoak Blowhole, at 173 m and 70 m below land surface, respectively. Following setup of the cave sites, dye injections were conducted to determine discharge points for four of the deep cave systems on Rich Mountain and Turkeypen ridge. Results show water in these systems has an extremely rapid travel time, with tracers detected from caves to springs in less than 24 h for each of the systems. This field guide describes the complex geology, regional hydrogeology, and unique landscape characterized by high-gradient subterranean streams, carbonate fensters, and deep caves of the GRSM karst.

North Carolina, Tennessee↗

USGS2015

Chemical concentrations and instantaneous loads, Green River to the Lower Duwamish Waterway near Seattle, Washington, 2013–15

In November 2013, U.S. Geological Survey streamgaging equipment was installed at a historical water-quality station on the Duwamish River, Washington, within the tidal influence at river kilometer 16.7 (U.S. Geological Survey site 12113390; Duwamish River at Golf Course at Tukwila, WA). Publicly available, real-time continuous data includes river streamflow, stream velocity, and turbidity. Between November 2013 and March 2015, the U.S. Geological Survey collected representative samples of water, suspended sediment, or bed sediment from the streamgaging station during 28 periods of differing flow conditions. Samples were analyzed by Washington-State-accredited laboratories for a large suite of compounds, including metals, dioxins/furans, semivolatile compounds including polycyclic aromatic hydrocarbons, pesticides, butytins, polychlorinated biphenyl (PCB) Aroclors and the 209 PCB congeners, volatile organic compounds, hexavalent chromium, and total and dissolved organic carbon. Metals, PCB congeners, and dioxins/furans were frequently detected in unfiltered-water samples, and concentrations typically increased with increasing suspended-sediment concentrations. Chemical concentrations in suspendedsediment samples were variable between sampling periods. The highest concentrations of many chemicals in suspended sediment were measured during summer and early autumn storm periods. Median chemical concentrations in suspended-sediment samples were greater than median chemical concentrations in fine bed sediment (less than 62.5 µm) samples, which were greater than median chemical concentrations in paired bulk bed sediment (less than 2 mm) samples. Suspended-sediment concentration, sediment particle-size distribution, and general water-quality parameters were measured concurrent with the chemistry sampling. From this discrete data, combined with the continuous streamflow record, estimates of instantaneous sediment and chemical loads from the Green River to the Lower Duwamish Waterway were calculated. For most compounds, loads were higher during storms than during baseline conditions because of high streamflow and high chemical concentrations. The highest loads occurred during dam releases (periods when stored runoff from a prior storm is released from the Howard Hanson Dam into the upper Green River) because of the high river streamflow and high suspended-sediment concentration, even when chemical concentrations were lower than concentrations measured during storm events.

Washington↗

USGS2010

Water-quality data for selected streams in the Mississippi Alluvial Plain ecoregion, northwestern Mississippi, September – October 2007

From September through October 2007, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, collected and analyzed water-quality samples from streams in the Yazoo River basin within the Mississippi Alluvial Plain ecoregion in northwestern Mississippi. Water-quality samples were collected at 56 sites in the study area and analyzed for various physical and chemical characteristics including, but not limited to, suspended sediment, nutrients, and chlorophyll a. Additionally, water temperature, pH, specific conductance, and dissolved oxygen data were measured at 28 of the sites using multiparameter water-quality meters at 30-minute intervals for a minimum of 48 hours. Data collected for this project will be used in the development of water-quality criteria for nutrients. The nutrient data will enhance existing datasets and support evaluation of cause and effect relations for nutrient criteria development. In addition, these indicators will assist in the development and evaluation of restoration and remediation plans for water bodies not meeting their designated uses, as stated in the U.S. Environmental Protection Agency's Clean Water Act Section 303(d).

Mississippi↗

USGS2019

Return flows from beaver ponds enhance floodplain-to-river metals exchange in alluvial mountain catchments

River to floodplain hydrologic connectivity is strongly enhanced by beaver- ( Castor canadensis ) engineered channel water diversions. The hydroecological impacts are wide ranging and generally positive, however, the hydrogeochemical characteristics of beaver-induced flowpaths have not been thoroughly examined. Using a suite of complementary ground- and drone-based heat tracing and remote sensing methodology we characterized the physical template of beaver-induced floodplain exchange for two alluvial mountain streams near Crested Butte, Colorado, USA. A flowpath-oriented perspective to water quality sampling allowed characterization of the chemical evolution of channel water diverted through floodplain beaver ponds and ultimately back to the channel in ‘beaver pond return flows’. Subsurface return flow seepages were universally suboxic, while ponds and surface return flows showed a range of oxygen concentration due to in-situ photosynthesis and atmospheric mixing. Median concentrations of reduced metals: manganese (Mn), iron (Fe), aluminum (Al), and arsenic (As) were substantially higher along beaver-induced flowpaths than in geologically controlled seepages and upstream main channel locations. The areal footprint of reduced return seepage flowpaths were imaged with surface electromagnetic methods, indicating extensive zones of high-conductivity shallow groundwater flowing back toward the main channels and emerging at relatively warm bank seepage zones observed with infrared. Multiple-depth redox dynamics within one focused seepage zone showed coupled variation over time, likely driven by observed changes in seepage rate that may be controlled by pond stage. High-resolution times series of dissolved Mn and Fe collected downstream of the beaver-impacted reaches demonstrated seasonal dynamics in mixed river metal concentrations. Al time series concentrations showed proportional change to Fe at the smaller stream location, indicating chemically reduced flowpaths were sourcing Al to the channel. Overall our results indicated beaver-induced floodplain exchanges create important, and perhaps dominant, transport pathways for floodplain metals by expanding chemically-reduced zones paired with strong advective exchange.

Colorado↗

USGS2011

Inorganic chemical analysis of environmental materials—A lecture series

At the request of the faculty of the Colorado School of Mines, Golden, Colorado, the authors prepared and presented a lecture series to the students of a graduate level advanced instrumental analysis class. The slides and text presented in this report are a compilation and condensation of this series of lectures. The purpose of this report is to present the slides and notes and to emphasize the thought processes that should be used by a scientist submitting samples for analyses in order to procure analytical data to answer a research question. First and foremost, the analytical data generated can be no better than the samples submitted. The questions to be answered must first be well defined and the appropriate samples collected from the population that will answer the question. The proper methods of analysis, including proper sample preparation and digestion techniques, must then be applied. Care must be taken to achieve the required limits of detection of the critical analytes to yield detectable analyte concentration (above "action" levels) for the majority of the study's samples and to address what portion of those analytes answer the research question-total or partial concentrations. To guarantee a robust analytical result that answers the research question(s), a well-defined quality assurance and quality control (QA/QC) plan must be employed. This QA/QC plan must include the collection and analysis of field and laboratory blanks, sample duplicates, and matrix-matched standard reference materials (SRMs). The proper SRMs may include in-house materials and/or a selection of widely available commercial materials. A discussion of the preparation and applicability of in-house reference materials is also presented. Only when all these analytical issues are sufficiently addressed can the research questions be answered with known certainty.

Open-File Report↗

USGS2008

Water- and air-quality monitoring of Sweetwater Reservoir watershed, San Diego County, California — Phase one results continued, 2001-2003

In 1998, the U.S. Geological Survey, in cooperation with the Sweetwater Authority, began a study to monitor water, air, and sediment at the Sweetwater and Loveland Reservoirs in San Diego County, California. The study includes regular sampling of water and air at Sweetwater Reservoir for chemical constituents, including volatile organic compounds (VOC), polynuclear aromatic hydrocarbons (PAH), pesticides, and major and trace elements. The purpose of this study is to monitor changes in contaminant composition and concentration during the construction and operation of State Route 125. To accomplish this, the study was divided into two phases. Phase One sampling (water years 1998–2004) determined baseline conditions for the detection frequency and the concentrations of target compounds in air and water. Phase Two sampling (starting water year 2005) continues at selected monitoring sites during and after construction of State Route 125 to assess the chemical impact this roadway alignment may have on water quality in the reservoir. Water samples were collected for VOCs and pesticides at Loveland Reservoir during Phase One and will be collected during Phase Two for comparison purposes. Air samples collected to monitor changes in VOCs, PAHs, and pesticides were analyzed by adapting methods used to analyze water samples. Bed-sediment samples have been and will be collected three times during the study; at the beginning of Phase One, at the start of Phase Two, and near the end of the study. In addition to the ongoing data collection, several special studies were initiated to assess the occurrence of specific chemicals of concern, such as trace metals, anthropogenic indicator compounds, and pharmaceuticals. This report describes the study design, and the sampling and analytical methods, and presents data from water and air samples collected during the fourth and fifth years of Phase One of the study (October 2001 to September 2003). Data collected during the first three years has been previously published. Three types of quality-control samples were used in this study: blanks, spikes, and replicates. Blanks and spikes are used to estimate result bias, and replicates are used to estimate result variability. Additionally, surrogate compounds were added at the laboratory to samples of VOCs, PAHs, pesticides, anthropogenic indicator compounds, and pharmaceuticals to monitor sample-specific performance of the analytical method.

California↗