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At least 1,171 records · Page 65Linked to original sources

USGS2003

Shifts in the diets of slimy sculpin ( Cottus cognatus ) and lake whitefish ( Coregonus clupeaformis ) in Lake Ontario following the collapse of the burrowing amphipod Diporeia

In Lake Ontario, the diets of slimy sculpin Cottus cognatus and lake whitefish Coregonus clupeaformis shifted from a diet dominated by the burrowing amphipod, Diporeia , and to a lesser extent, Mysis , to a more diverse diet, after Diporeia collapsed, to one dominated by Mysis and prey that were formerly less important or uncommon such as Chironomidae, Oligochaeta, and Ostracoda. Additionally, lake whitefish still preyed on native mollusks like Sphaeriidae and Gastropoda, but also preyed on exotic mollusks, Dreissena spp., which are swallowed intact and subsequently crushed in its muscular stomach. Whether Diporeia was abundant (1992) or scarce (1999), selection indices for Diporeia by slimy sculpins was positive, suggesting that Diporeia was a preferred prey. Unlike lake whitefish, slimy sculpins avoided Dreissena ; therefore, energy diverted to Dreissena production was a real loss for slimy sculpins. The shifts in the diet of these benthic fishes corresponded with drastic changes in the benthic community between 1992 and 1999. The collapse of Diporeia , formerly the most abundant macroinvertebrate in the benthic community, along with sharp declines in the abundance of Oligochaeta and Sphaeriidae, coincided with the establishment and rapid expansion of Dreissena bugensis , the quagga mussel, and to a lesser degree Dreissena polymorpha , the zebra mussel. It appears that the Diporeia population first collapsed at depths >70 m in southeastern Lake Ontario by autumn 1992, at shallower depths in the eastern Lake Ontario by 1995, and along the entire south shore line at depths <100 m, and perhaps in some areas >100 m by 1999. In response to the disappearance of Diporeia , populations of two native benthivores, slimy sculpin and lake whitefish, collapsed in eastern Lake Ontario, perhaps due in part to starvation, because Diporeia was their principal prey. Presently, alternative food resources do not appear sufficient to sustain these two benthivores at their former levels of abundance. We do not expect slimy sculpin and lake whitefish to recover unless Diporeia returns to earlier levels of abundance.

Aquatic Ecosystem Health & Management↗

USGS2005

Environmental setting, water budget, and stream assessment for the Broad Run watershed, Chester County, Pennsylvania

The Broad Run watershed lies almost entirely in West Bradford Township, Chester County, Pa., and drains 7.08 square miles to the West Branch Brandywine Creek. Because of the potential effect of encroaching development and other stresses on the Broad Run watershed, West Bradford Township, the Chester County Water Resources Authority, and the Chester County Health Department entered into a cooperative study with the U.S. Geological Survey to complete an annual water budget and stream assessment of overall conditions. The annual water budget quantified the basic parameters of the hydrologic cycle for the climatic conditions present from April 1, 2003, to March 31, 2004. These water-budget data identified immediate needs and (or) deficits that were present within the hydrologic cycle during that period, if present; however, an annual water budget encompassing a single year does not identify long-term trends. The stream assessment was conducted in two parts and assessed the overall condition of the watershed, an overall assessment of the fluvial-geomorphic conditions within the watershed and an overall assessment of the stream-quality conditions. The data collected will document present (2004) conditions and identify potential vulnerabilities to future disturbances. For the annual period from April 1, 2003, to March 31, 2004, determination of an annual water budget indicated that of the 67.8 inches of precipitation that fell on the Broad Run watershed, 38.8 inches drained by way of streamflow to the West Branch Brandywine Creek. Of this 38.8 inches of streamflow, local-minimum hydrograph separation techniques determined that 7.30 inches originated from direct runoff and 31.5 inches originated from base flow. The remaining precipitation went into ground-water storage (1.71 inches) and was lost to evapotranspiration (27.3 inches). Ground-water recharge for this period-35.2 inches-was based on these values and an estimated ground-water evapotranspiration rate of 2 inches. Assessment of fluvial-geomorphic conditions included large-scale mapping of stream classes within the Broad Run watershed and in-depth study of three representative stream reaches also within the Broad Run watershed. Based on the total distance of all stream reaches classified within the Broad Run watershed, 61 percent were classified as C-class, 14 percent as E-class, 13 percent as B-class, 5 percent as F-class, 4 percent as undifferentiated B- and F-class, 2 percent as G-class, and less than 1 percent as A-class. The map of stream classes indicates that the Broad Run watershed currently has no large-scale areas of stream impairment and that, generally, the stream is not entrenched and the main branch of the Broad Run has an available, functioning flood plain. Smaller tributary streams, however, showed signs of localized entrenchment due to site-specific influences such as natural stream-channel evolution, localized channelization, localized contraction due to road and driveway crossings, and (or) increased localized runoff. For example, one small reach along a tributary channel was observed to become entrenched due to runoff originating from a new housing development. Entrenched stream reaches are merely located by large-scale mapping and require individual assessment to determine potential causes of entrenchment and (or) future restorative actions. Three in-depth geomorphic study sites showed that the Broad Run can currently be considered graded or in a state of dynamic equilibrium. The sites did, however, identify certain vulnerabilities to future changes within the watershed. These vulnerabilities included disruption of the present sediment supply, including both increases and (or) reductions in the current sediment loads within the Broad Run; increases in both magnitude and duration of storm-water runoff; encroachment of development onto present flood-plain areas, and (or) alterations to riparian zones. Assessment of stream-quality conditions includ

Scientific Investigations Report↗

USGS2012

Prioritizing pesticide compounds for analytical methods development

The U.S. Geological Survey (USGS) has a periodic need to re-evaluate pesticide compounds in terms of priorities for inclusion in monitoring and studies and, thus, must also assess the current analytical capabilities for pesticide detection. To meet this need, a strategy has been developed to prioritize pesticides and degradates for analytical methods development. Screening procedures were developed to separately prioritize pesticide compounds in water and sediment. The procedures evaluate pesticide compounds in existing USGS analytical methods for water and sediment and compounds for which recent agricultural-use information was available. Measured occurrence (detection frequency and concentrations) in water and sediment, predicted concentrations in water and predicted likelihood of occurrence in sediment, potential toxicity to aquatic life or humans, and priorities of other agencies or organizations, regulatory or otherwise, were considered. Several existing strategies for prioritizing chemicals for various purposes were reviewed, including those that identify and prioritize persistent, bioaccumulative, and toxic compounds, and those that determine candidates for future regulation of drinking-water contaminants. The systematic procedures developed and used in this study rely on concepts common to many previously established strategies. The evaluation of pesticide compounds resulted in the classification of compounds into three groups: Tier 1 for high priority compounds, Tier 2 for moderate priority compounds, and Tier 3 for low priority compounds. For water, a total of 247 pesticide compounds were classified as Tier 1 and, thus, are high priority for inclusion in analytical methods for monitoring and studies. Of these, about three-quarters are included in some USGS analytical method; however, many of these compounds are included on research methods that are expensive and for which there are few data on environmental samples. The remaining quarter of Tier 1 compounds are high priority as new analytes. The objective for analytical methods development is to design an integrated analytical strategy that includes as many of the Tier 1 pesticide compounds as possible in a relatively few, cost-effective methods. More than 60 percent of the Tier 1 compounds are high priority because they are anticipated to be present at concentrations approaching levels that could be of concern to human health or aquatic life in surface water or groundwater. An additional 17 percent of Tier 1 compounds were frequently detected in monitoring studies, but either were not measured at levels potentially relevant to humans or aquatic organisms, or do not have benchmarks available with which to compare concentrations. The remaining 21 percent are pesticide degradates that were included because their parent pesticides were in Tier 1. Tier 1 pesticide compounds for water span all major pesticide use groups and a diverse range of chemical classes, with herbicides and their degradates composing half of compounds. Many of the high priority pesticide compounds also are in several national regulatory programs for water, including those that are regulated in drinking water by the U.S. Environmental Protection Agency under the Safe Drinking Water Act and those that are on the latest Contaminant Candidate List. For sediment, a total of 175 pesticide compounds were classified as Tier 1 and, thus, are high priority for inclusion in analytical methods available for monitoring and studies. More than 60 percent of these compounds are included in some USGS analytical method; however, some are spread across several research methods that are expensive to perform, and monitoring data are not extensive for many compounds. The remaining Tier 1 compounds for sediment are high priority as new analytes. The objective for analytical methods development for sediment is to enhance an existing analytical method that currently includes nearly half of the pesticide compounds in Tier 1 by adding as many additional Tier 1 compounds as are analytically compatible. About 35 percent of the Tier 1 compounds for sediment are high priority on the basis of measured occurrence. A total of 74 compounds, or 42 percent, are high priority on the basis of predicted likelihood of occurrence according to physical-chemical properties, and either have potential toxicity to aquatic life, high pesticide useage, or both. The remaining 22 percent of Tier 1 pesticide compounds were either degradates of Tier 1 parent compounds or included for other reasons. As with water, the Tier 1 pesticide compounds for sediment are distributed across the major pesticide-use groups; insecticides and their degradates are the largest fraction, making up 45 percent of Tier 1. In contrast to water, organochlorines, at 17 percent, are the largest chemical class for Tier 1 in sediment, which is to be expected because there is continued widespread detection in sediments of persistent organochlorine pesticides and their degradates at concentrations high enough for potential effects on aquatic life. Compared to water, there are fewer available benchmarks with which to compare contaminant concentrations in sediment, but a total of 19 Tier 1 compounds have at least one sediment benchmark or screening value for aquatic organisms. Of the 175 compounds in Tier 1, 77 percent have high aquatic-life toxicity, as defined for this process. This evaluation of pesticides and degradates resulted in two lists of compounds that are priorities for USGS analytical methods development, one for water and one for sediment. These lists will be used as the basis for redesigning and enhancing USGS analytical capabilities for pesticides in order to capture as many high-priority pesticide compounds as possible using an economically feasible approach.

Scientific Investigations Report↗

USGS2024

Growth, survival, and cohort formation of juvenile Lost River (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California—2021–22 monitoring report

Executive Summary The work reported in this publication provides updated data and interpretation for sampling years 2015 and 2022 of the juvenile monitoring project. The study objectives, background, study area, species description, and methods remained the same or similar throughout the years, while the executive summary, results, and discussion were updated each year. Therefore much of this paper was originally presented in previous reports (Bart and others 2020a, b; Bart and others, 2021; Burdick and others, 2016; Burdick and others, 2018; Martin and others, 2022) and is repeated here for the reader’s convenience. Populations of federally endangered Lost River ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) in Upper Klamath Lake, Oregon, and Clear Lake Reservoir (hereinafter, Clear Lake), California, are experiencing long-term decreases in abundance. Upper Klamath Lake populations are decreasing not only because of adult mortality, which is relatively low, but also because they are not being balanced by recruitment of young adult suckers into adult spawning aggregations. Long-term monitoring of juvenile sucker populations is conducted to (1) determine if there are annual and species-specific differences in production, survival, and growth; (2) better understand when juvenile sucker mortality is greatest; and (3) identify potential causes of high juvenile sucker mortality particularly in Upper Klamath Lake. The U.S. Geological Survey (USGS) monitoring program, begun in 2015, tracks cohorts through summer months and among years in Upper Klamath and Clear Lakes. Data on juvenile suckers captured in trap nets are used to provide information on annual variability in age-0 sucker production, juvenile sucker apparent survival, growth, species composition, and health. Upper Klamath Lake indices of year-class strength suggest that the 2022 age-0 cohort is the lowest since standardized monitoring began. The 2021 cohort, like most cohorts, had moderately low catch rates their first year of life, with a steep drop off during the second year. Although the 2020 cohort persisted through the September 2022 sampling, this cohort was sparsely represented after the first year with no representatives from this cohort captured from July 2021 through July 2022. Despite apparently low fall through spring apparent survival, the relatively large 2019 cohort persisted in our 2020–21 samples, but has not been detected since June 2021. Klamath largescale ( Catostomus snyderi ) and shortnose suckers were only differentiated from each other starting in 2020. Shortnose suckers dominated the age-1 catch in 2020 and 2022, whereas age-1 Klamath largescale suckers were slightly more prevalent in 2021. Although there were occasionally age-2 and older suckers captured, none of these fish were Lost River suckers. Except for 2015, 2017, and 2021, there were more age-0 Lost River suckers than presumed shortnose suckers in Upper Klamath Lake. However, in all years sampled, there were more age-1 presumed shortnose suckers than Lost River suckers. Age distribution of suckers captured in Clear Lake indicates greater juvenile survival than in Upper Klamath Lake. Most juvenile suckers captured throughout the years were from the 2016 and 2017 cohorts; however, by 2022 most of these fish were no longer susceptible to standard trap nets and were not as prevalent in 2022 juvenile catches, and these suckers presumedly recruited to the adult population. As the 2016 and 2017 cohorts catches declined, so did the catch in overall numbers of suckers. Excluding age-0 catches, the 2016 cohort catches peaked at age-3 and the 2017 catches peaked at age-2. In 2022, the majority of the catch was composed of age-3 to age-5 suckers. The majority of suckers captured in Clear Lake during this multiyear project were classified as the combination of Klamath largescale suckers and shortnose suckers from the Lost River Basin, from the 2016 and 2017 cohorts. The few suckers identified as Lost River or definitive shortnose suckers were from the 2016 and 2017 cohorts. A lack of age-0 suckers captured in Clear Lake during years with low spawning tributary inflow or lake levels suggested that low water prevented spawning and year class formation. However, recent data indicate that some cohorts with Klamath largescale and shortnose sucker genetics that were not captured as age-0 suckers were detected in later years at age-1 or age-2. This finding indicates that juvenile suckers in Clear Lake may spend one or more years in the tributaries and that these cohorts may primarily be represented by Klamath largescale suckers. The first 7 years of this monitoring program indicated different patterns in recruitment and survival of juvenile suckers between Upper Klamath and Clear Lakes. Since the monitoring program began in 2015, age-0 sucker catch rates, interpreted as indices of year-class strength, were greatest in Upper Klamath Lake in 2016 and 2019. In those years, Lost River suckers made up the majority of age-0 sucker catches. However, in 2017 and 2020, the age-1 sucker catches from these cohorts were mainly composed of shortnose suckers or suckers with genetic markers of both Klamath largescale and shortnose suckers, indicating a low first year survival for Lost River suckers even when age-0 catches were high. Age-0 suckers do not fully recruit to our sampling gear in Upper Klamath Lake until August, experience high mortality by September, and are almost undetectable in subsequent years. In Clear Lake, suckers are often not captured until age-1 or age-2 and juvenile annual survival appears much greater; however, there does appear to be a drop-off in catch rates as the suckers age and become less susceptible to the fishing gear.

California, Oregon↗

USGS2006

Abstracts of the Annual Meeting of Planetary Geologic Mappers, Nampa, Idaho 2006

Approximately 18 people attended this year's mappers meeting, and many more submitted abstracts and maps in absentia. The meeting was held on the campus of Northwest Nazarene University (NNU), and was graciously hosted by NNU's School of Health and Science. Planetary mapper Dr. Jim Zimbelman is an alumnus of NNU, and he was pivotal in organizing the meeting at this location. Oral and poster presentations were given on Friday, June 30. Drs. Bill Bonnichsen and Marty Godchaux led field excursions on July 1 and 2. USGS Astrogeology Team Chief Scientist Lisa Gaddis led the meeting with a brief discussion of the status of the planetary mapping program at USGS, and a more detailed description of the Lunar Mapping Program. She indicated that there is now a functioning website (http://astrogeology.usgs.gov/Projects/PlanetaryMapping/Lunar/) which shows which lunar quadrangles are available to be mapped. Like other USGS-published maps, proposals to complete a lunar geologic map must be submitted to the regular Planetary Geology & Geophysics (PGG) program for peer review. Jim Skinner (USGS) later presented the progress of the 1:2.5M-scale map of the lunar Copernicus quadrangle, and demonstrated the wide range of data that are available to support these maps. Gaddis and Skinner encouraged the community to submit proposals for generating lunar geologic maps, and reminded us that, as for all planetary maps, the project must be science-driven. Venus mapper Jim Zimbelman of the Smithsonian Institution (SI) presented the progress for his V-15 and V-16 quadrangles; Vicki Hansen (University of Minnesota Duluth) showed her preliminary work on V-45. Zimbelman addressed an issue that has been plaguing the community: 'delinquent Venus mappers'. In short, there were a number of Venus maps funded in the early 1990s under the Venus Data Analysis Program (VDAP). Unfortunately, funding for this program was cut before many Venus maps could be completed, resulting in about 10 Venus maps that were initially assigned but have shown little or no progress in many years. Zimbelman announced that he was not going to be able to complete quadrangle V-27 that he was assigned under VDAP, and was therefore returning that quadrangle to the community; he invited people to propose to PGG to map this quadrangle. Dave Williams of Arizona State University (ASU) reported on the progress of his global Io map. His mapping team recently received the completed, controlled global mosaic (using Voyager and Galileo images) from the USGS; this will be the basemap for their geologic mapping. Furthermore, the three team members (Laszlo Keszthelyi, David Crown and Dave Williams) have calibrated their individual mapping techniques by each mapping the same region for comparison. Thomas Doggett (ASU) showed progress on the global Europa map that was awarded to Ron Greeley. There was some consternation expressed on the methodology for determining relative ages of the lineaments; it was suggested that Vicki Hansen contact Patricio Figueredo (Exxon) directly, because Figueredo is the one who has been developing the lineament mapping techniques. Mars remains the most popular planet to map. Kevin Williams (SI) and Corey Fortezzo (SI) presented progress on their 1:500K maps in the Margaritifer Terra region of Mars. Jim Zimbelman described his 1:1M Medusae Fossae map, which is nearing completion. Peter Mouginis-Mark (University of Hawai'i) reported progress on his 1:200K maps of Tooting crater and of the Olympus Mons summit caldera. Jim Skinner discussed the progress of his and Ken Herkenhoff?s (USGS) map (1:500K) on the Olympia Cavi region of Mars? north pole, and Eric Kolb (USGS) presented work that he and Ken Tanaka (USGS) are completing on the Martian south pole. David Crown of the Planetary Science Institute (PSI) reported on numerous 1:500K and 1:1M maps in the Hellas and Hesperia regions of Mars. Frank Chuang (PSI) discussed progress on mapping the Deuteronilus Mensae reg

Open-File Report↗

USGS2010

Assessment of arsenic concentrations in domestic well water, by town, in Maine 2005-09

Prior studies have established that approximately 10 percent of domestic wells in Maine have arsenic levels greater than the U.S. Environmental Protection Agency maximum contaminant limit (10 micrograms per liter (ug/L)). Of even greater concern are multiple discoveries of wells with very high arsenic levels (> 500 ug/L) in several areas of the State. A study was initiated to assist the Maine Center for Disease Control and Prevention (ME-CDC) in developing a better understanding of the statewide spatial occurrence of wells with elevated arsenic levels at the individual town level, identify areas of the State that should be targeted for increased efforts to promote well-water testing, and generate data for potential use in predicting areas of the State likely to have very high levels of arsenic. The State's Health and Environmental and Testing Laboratory (HETL) annually analyzes samples from thousands of domestic wells for arsenic. Results of arsenic analyses of domestic well water submitted to the HETL from 2005 to 2009 were screened and organized, by town, in order to summarize the results for all towns with samples submitted to the HETL. In order to preserve the privacy of well owners, the screening and organization of samples was conducted in the offices of the ME-CDC, following applicable Maine and United States laws, rules, and privacy policies. After screening, the database contained samples from 531 towns in Maine and from 11,111 individual wells. Of those towns, 385 had samples from 5 or more individual wells, 174 towns had samples from 20 or more individual wells, and 49 towns had samples from 60 or more wells. These samples, because they were submitted by homeowners and were not part of a random sample, may not be representative of all wells in a given area. The minimum, maximum, and median arsenic values for the towns with five or more samples were calculated, and the maximum and median values were mapped for the State. The percentages of samples exceeding 10, 50, 100, and 500 ug/L were calculated for the 174 towns with 20 or more sampled wells, and statewide maps were prepared for each of these categories. More than 25 percent of the sampled wells in 44 towns exceeded 10 ug/L. Many fewer towns had wells with samples that exceeded the 50, 100, or 500 ug/L categories. For 19 towns, more than 10 percent of the sampled wells had arsenic concentrations that exceeded 50 ug/L, and in 45 towns, 1 percent or more exceeded 100 ug/L. Of these, Surry in Hancock County had 120 wells tested, and 23 percent of those wells had arsenic concentrations that exceeded 100 ug/L, which is a much higher rate than for other towns. In only four towns (Danforth in Washington County, Surry and Blue Hill in Hancock County, and Woolwich in Sagadahoc County), 1 percent or more of the sampled wells had arsenic concentrations greater than 500 ug/L during 2005-09. The distribution of high arsenic concentrations in wells follows some geographic patterns, which are generally geologically controlled. There are clusters or belts of towns with high arsenic concentrations (> 50 ug/L), such as in southern coastal areas, the Kennebec County area, and towns along the central coastal part of Maine. In contrast, there are areas of the State with low arsenic concentrations, such as the northernmost towns, as well as towns in the western and west-central areas. There appear to be three distinct large-scale areas of high concentrations of arsenic in groundwater-one in southern coastal areas, one in central Kennebec County, and one in the town of Ellsworth (Hancock County) and the surrounding areas. In addition, several smaller clusters of isolated high concentrations of arsenic in groundwater exist. Earlier testing has identified other clusters of very high arsenic concentrations in groundwater in the towns of Northport, Buxton/Hollis, and Waldoboro, but those samples were collected before 2005 and did not factor in this analysis.

Scientific Investigations Report↗

USGS2020

Identifying reliable indicators of fitness in polar bears

Animal structural body size and condition are often measured to evaluate individual health, identify responses to environmental change and food availability, and relate food availability to effects on reproduction and survival. A variety of condition metrics have been developed but relationships between these metrics and vital rates are rarely validated. Identifying an optimal approach to estimate the body condition of polar bears is needed to improve monitoring of their response to decline in sea ice habitat. Therefore, we examined relationships between several commonly used condition indices (CI), body mass, and size with female reproductive success and cub survival among polar bears ( Ursus maritimus ) measured in two subpopulations over three decades. To improve measurement and application of morphometrics and CIs, we also examined whether CIs are independent of age and structural size–an important assumption for monitoring temporal trends—and factors affecting measurement precision and accuracy. Maternal CIs and mass measured the fall prior to denning were related to cub production. Similarly, maternal CIs, mass, and length were related to the mass of cubs or yearlings that accompanied her. However, maternal body mass, but not CIs, measured in the spring was related to cub production and only maternal mass and length were related to the probability of cub survival. These results suggest that CIs may not be better indicators of fitness than body mass in part because CIs remove variation associated with body size that is important in affecting fitness. Further, CIs exhibited variable relationships with age for growing bears and were lower for longer bears despite body length being related to cub survival and female reproductive success. These results are consistent with findings from other species indicating that body mass is a useful metric to link environmental conditions and population dynamics.

PLoS ONE↗

USGS1998

Water-quality assessment of the Central Arizona Basins, Arizona and northern Mexico – Environmental setting and overview of water quality

The Central Arizona Basins study area in central and southern Arizona and northern Mexico is one of 60 study units that are part of the U.S. Geological Survey's National Water-Quality Assessment program. The purpose of this report is to describe the physical, chemical, and environmental characteristics that may affect water quality in the Central Arizona Basins study area and present an overview of water quality. Covering 34,700 square miles, the study area is characterized by generally north to northwestward-trending mountain ranges separated by broad, gently sloping alluvial valleys. Most of the perennial rivers and streams are in the northern part of the study area. Rivers and streams in the south are predominantly intermittent or ephemeral and flow in response to precipitation such as summer thunderstorms. Effluent-dependent streams do provide perennial flow in some reaches. The major aquifers in the study area are in the basin-fill deposits that may be as much as 12,000 feet thick. The 1990 population in the study area was about 3.45 million, and about 61 percent of the total was in Maricopa County (Phoenix and surrounding cities). Extensive population growth over the past decade has resulted in a twofold increase in urban land areas and increased municipal water use; however, agriculture remains the major water use. Seventy-three percent of all water with drawn in the study area during 1990 was used for agricultural purposes. The largest rivers in the study area-the Gila, Salt, and Verde-are perennial near their headwaters but become intermittent downstream because of impoundments and artificial diversions. As a result, the Central Arizona Basins study area is unique compared to less arid basins because the mean surface-water outflow is only 528 cubic feet per second from a total drainage area of 49,650 square miles. Peak flows in the northern part of the study area are the result of snowmelt runoff; whereas, summer thunderstorms account for the peak flows in the southern part. Ground water is the primary water supply in most of Arizona and the only source of drinking water used by communities in the southern half of the study area. Years of overpumping have caused water tables in basin fill to drop below once-perennial streams leaving streambeds dry, water too deep to pump economically, pumping of poorer quality water with depth, and earth fissures resulting from subsidence after dewatering of sediments. Natural processes-such as leaching of trace elements and major ions from geologic formations-and human activities-such as mining, agriculture, and urban development-have major effects on the quality of surface-water and ground-water resources in the Central Arizona Basins study area. Surface-water quality standards in Arizona are based on the designated use of the water such as full or partial body contact, fish consumption, aquatic and wildlife uses, and agriculture. Maintaining the biological integrity (health) of surface waters in Arizona is an important part of ensuring that these waters are suitable for designated uses. Important water-quality issues for surface water that are somewhat unique to Arizona include: (1) streamflows and riparian environments sustained by effluent from municipal wastewater-treatment plants that contains high concentrations of nutrients, potentially toxic trace elements and organic compounds, and fecal bacteria; (2) industrial, mining, agricultural, and municipal sources of contamination from Mexico; and (3) unpredictable high flows from major summer thunder storms causing stream-channel changes; high suspended-sediment concentrations and loads; sewage overflows; and breaching, erosion, and washout of landfills and mining operations. The quality of water in aquifers that are protected for drinking- water use is subject to standards that are in most cases equal to or more stringent than the primary drinking-water regulations of the U.S. Environmental Protection Agency. The general che

Arizona↗

USGS2014

Wildland fire ash: Production, composition and eco-hydro-geomorphic effects

Fire transforms fuels (i.e. biomass, necromass, soil organic matter) into materials with different chemical and physical properties. One of these materials is ash, which is the particulate residue remaining or deposited on the ground that consists of mineral materials and charred organic components. The quantity and characteristics of ash produced during a wildland fire depend mainly on (1) the total burned fuel (i.e. fuel load), (2) fuel type and (3) its combustion completeness. For a given fuel load and type, a higher combustion completeness will reduce the ash organic carbon content, increasing the relative mineral content, and hence reducing total mass of ash produced. The homogeneity and thickness of the ash layer can vary substantially in space and time and reported average thicknesses range from close to 0 to 50 mm. Ash is a highly mobile material that, after its deposition, may be incorporated into the soil profile, redistributed or removed from a burned site within days or weeks by wind and water erosion to surface depressions, footslopes, streams, lakes, reservoirs and, potentially, into marine deposits. Research on the composition, properties and effects of ash on the burned ecosystem has been conducted on material collected in the field after wildland and prescribed fires as well as on material produced in the laboratory. At low combustion completeness (typically T < 450 °C), ash is organic-rich, with organic carbon as the main component. At high combustion completeness (T > 450 °C), most organic carbon is volatized and the remaining mineral ash has elevated pH when in solution. It is composed mainly of calcium, magnesium, sodium, potassium, silicon and phosphorous in the form of inorganic carbonates, whereas at T > 580 °C the most common forms are oxides. Ash produced under lower combustion completeness is usually darker, coarser, and less dense and has a higher saturated hydraulic conductivity than ash with higher combustion completeness, although physical reactions with CO 2 and when moistened produce further changes in ash characteristics. As a new material present after a wildland fire, ash can have profound effects on ecosystems. It affects biogeochemical cycles, including the C cycle, not only within the burned area, but also globally. Ash incorporated into the soil increases temporarily soil pH and nutrient pools and changes physical properties such as albedo, soil texture and hydraulic properties including water repellency. Ash modifies soil hydrologic behavior by creating a two-layer system: the soil and the ash layer, which can function in different ways depending on (1) ash depth and type, (2) soil type and (3) rainfall characteristics. Key parameters are the ash's water holding capacity, hydraulic conductivity and its potential to clog soil pores. Runoff from burned areas carries soluble nutrients contained in ash, which can lead to problems for potable water supplies. Ash deposition also stimulates soil microbial activity and vegetation growth. Further work is needed to (1) standardize methods for investigating ash and its effects on the ecosystem, (2) characterize ash properties for specific ecosystems and wildland fire types, (3) determine the effects of ash on human and ecosystem health, especially when transported by wind or water, (4) investigate ash's controls on water and soil losses at slope and catchment scales, (5) examine its role in the C cycle, and (6) study its redistribution and fate in the environment.

Earth-Science Reviews↗

USGS2000

Microbiological and chemical quality of ground water used as a source of public supply in southern Missouri — Phase II, April–July, 1998

The protection of public health through quality public ground-water systems is the responsibility of the U. S. Environmental Protection Agency and the State of Missouri, through the Missouri Department of Natural Resources, Public Drinking Water Program. Approximately 95 percent of the public-water supplies in Missouri use ground water as their source of drinking water through more than 3,700 public wells. Karst terrain, intensive agricultural operations, extensive numbers of on-site sewage systems, and poor well construction can lead to chemical and microbiological contamination of the contributing aquifers. Sitespecific studies and routine regulatory monitoring have produced information on the overall quality and potability of the State's public-drinking-water supplies, but little is known about the presence of viruses. The U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, sampled 109 public-water supplies to characterize the physical, chemical, bacterial, and viral conditions in southern Missouri. During April to July 1998, these wells were sampled for nutrients, total organic carbon, optical brighteners, indicator bacteria, enteric viruses, and ribonucleic acid and somatic coli phages. These constituents indicate possible surface contamination of the sampled aquifer. Selection of the wells to be sampled depended on the age of the well (pre-1970), land use, geohydrology, and well construction. None of the physical or chemical constituents measured or analyzed exceeded Missouri's Drinking Water Standards set by the Public Drinking Water Program of the Missouri Department of Natural Resources. The majority of ammonia plus organic nitrogen, nitrite, and phosphorus concentrations were below the laboratory's minimum reporting levels. There were a greater number of detects above the minimum reporting level with respect to the nitrite plus nitrate, ammonia, orthophosphate, and total organic carbon concentrations. Analyses included comparing and contrasting the data by grouping according to well age and construction, karst type, geohydrology, soil type, and land use. There was little variation in well construction between selected wells. The results indicated several groupings of similar and dissimilar concentrations, most expected because of hydrological, physical, or land use differences. Dissolved oxygen values indicated distinct variation in the different groupings. There were significant differences in dissolved oxygen values between the secondary and non-karst areas, the Ozark confined and Ozark unconfined geohydrologic groups, and between agricultural and other land uses. In groupings by soil and geohydrology, the Missouri bootheel region differed with respect to ammonia, total organic carbon, and phosphorus when compared with the other groups. Less than 10 percent of the wells sampled tested positive for bacterial contamination. E. coli was the most frequently detected bacterium. The public wells at Monett and West Plains, Missouri, had plates with colonies too numerous to count for all three indicator bacteria. Further analyses by rRNA (ribosomal RiboNucleic Acid) hybridization techniques detennined that much of the bacteria present were from ruminant and human sources. No enteric viruses were detected in the 109 samples. Both ribonucleic acid and somatic coliphage were detected at two wells. One additional well had ribonucleic acid coliphage and another had somatic coliphage for a total of four wells with coliphage selects.

Missouri↗

USGS1997

Water-quality assessment of the Ozark Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma: Organic compounds in surface water, bed sediment, and biological tissue, 1992-95

Organic-compound samples, including pesticides and semi-volatiles, were collected from 1992-95 at 43 surface-water and 27 bed-sediment and biological-tissue sampling sites within the Ozark Plateaus National Water-Quality Assessment Program study unit. Most surface-water, bed-sediment, and biological-tissue sites have drainage basins predominantly in the Springfield and Salem Plateaus. At most surface-water sampling sites, one to three pesticide samples were collected in the spring and early summer of 1994 and 1995; two sites had additional samples collected either weekly, biweekly, or monthly from February 1994 through December 1994. At most bed-sediment and biological-tissue sampling sites, a single organic-compounds sample was collected. Agricultural pesticide use was approximately 4.9 million pounds of active ingredients per year from 1987-91 in the study unit and was generally greatest in the Springfield and Salem Plateaus pasturelands and in the Osage Plains and Mississippi Alluvial Plain cropland areas. The most frequently applied pesticide in the study unit was 2,4-D. Atrazine was the second most frequently applied pesticide. Corn, pasture, rice, sorghum, and soybeans received approximately 85 percent of the pesticides applied within the study unit. The highest pesticide application rate occurred on these crops in the Mississippi Alluvial and Osage Plains. Pastureland was the crop type that received the greatest amount of pesticides in 53 of the 96 counties in the study unit. The most commonly detected herbicide (63 samples) in surface water was atrazine. Five other pesticides--desethylatrazine, tebuthiuron, prometon, metolachlor, and simazine--were detected in 15 or more samples. The most commonly detected insecticide (13 samples) was p,p'-DDE. Two other insecticides, diazinon and cis-permethrin, were detected in seven or more samples. Pesticides were detected at 39 surface-water sites; samples collected at Yocum Creek near Oak Grove, Ark. had the most pesticide detections (13). Seventeen other sites had samples with six or more pesticide detections. Analysis of pesticide data collected at surface-water sites indicates that the largest variety of different pesticides detected (18) was in small, agricultural drainage basins; the largest percentage of detections of a single pesticide (about 80) was in medium, agricultural basins. Pesticide concentrations were small, and in most cases, at or near the detection limit. Maximum concentrations ranged from 0.001 to 0.007 micrograms per liter (mg/L) at small, forest sites; 0.001 to 0.029 mg/L at medium, forest sites; 0.001 to 0.079 mg/L at small, agricultural sites; and 0.003 to 0.29 mg/L at medium, agricultural sites. Pesticides were detected significantly more often in medium, agricultural basins in the Springfield Plateau. The most commonly detected (13 samples) organic compound in bed sediment, in concentrations noticeably above background levels, was 2,6-dimethylnaphthalene; the maximum concentration of 2,6-dimethylnaphthalene was 130 micrograms per kilogram. Seventeen or more compounds were detected in bed-sediment samples collected at three sites. Four compounds were detected in biological-tissue samples: p,p'-DDT in Corbicula fluminea (Asiatic clam) tissue collected at the Osage River near St. Thomas, Mo. and cis-chlordane, trans-chlordane, and trans-nonachlor in C. fluminea tissue collected at the James River near Boaz, Mo. Organic compounds collected at surface-water, bed-sediment, or biological-tissue sampling sites were not detected in concentrations that exceeded any health criteria or standards. Based on this information, organic compounds do not pose any widespread or persistent problems in the study unit.

Arkansas, Kansas, Missouri, Oklahoma↗

USGS2004

Chester County ground-water atlas, Chester County, Pennsylvania

Chester County encompasses 760 square miles in southeastern Pennsylvania. Groundwater-quality studies have been conducted in the county over several decades to address specific hydrologic issues. This report compiles and describes water-quality data collected during studies conducted mostly after 1990 and summarizes the data in a county-wide perspective. In this report, water-quality constituents are described in regard to what they are, why the constituents are important, and where constituent concentrations vary relative to geology or land use. Water-quality constituents are grouped into logical units to aid presentation: water-quality constituents measured in the field (pH, alkalinity, specific conductance, and dissolved oxygen), common ions, metals, radionuclides, bacteria, nutrients, pesticides, and volatile organic compounds. Water-quality constituents measured in the field, common ions (except chloride), metals, and radionuclides are discussed relative to geology. Bacteria, nutrients, pesticides, and volatile organic compounds are discussed relative to land use. If the U.S. Environmental Protection Agency (USEPA) or Chester County Health Department has drinking water standards for a constituent, the standards are included. Tables and maps are included to assist Chester County residents in understanding the water-quality constituents and their distribution in the county. Ground water in Chester County generally is of good quality and is mostly acidic except in the carbonate rocks and serpentinite, where it is neutral to strongly basic. Calcium carbonate and magnesium carbonate are major constituents of these rocks. Both compounds have high solubility, and, as such, both are major contributors to elevated pH, alkalinity, specific conductance, and the common ions. Elevated pH and alkalinity in carbonate rocks and serpentinite can indicate a potential for scaling in water heaters and household plumbing. Low pH and low alkalinity in the schist, quartzite, and gneiss rocks can indicate a potential for corrosive water. The only constituent measured in the field that has a USEPA Secondary Maximum Contaminant Level (SMCL) is pH. The SMCL for pH is 6.5-8.5; 64 percent of samples analyzed for pH were acidic (below pH 6.5). Only 1 percent of samples were basic (above pH 8.5). Of the common ions, the USEPA has SMCLs for chloride, sulfate, and total dissolved solids. The USEPA has a SMCL and a Primary Maximum Contaminant Level (PMCL) for fluoride. Chloride is more closely related to land use than geology. In Chester County, chloride exceeded the SMCL (250 mg/L) only in 5 percent of the services (commercial services, community services, and military) land-use areas. No samples analyzed for sulfate exceeded the SMCL (250 mg/L). Only 3 percent of samples analyzed for total dissolved solids exceeded the SMCL (500 milligrams per liter) (mg/L). No samples analyzed for fluoride equaled or exceeded the SMCL (2.0 mg/L) or PMCL (4.0 mg/L). Iron concentrations exceeded the USEPA SMCL in 11 percent of samples and were highest in schist (14 percent) and gneiss (13 percent). Manganese concentrations exceeded the SMCL in 19 percent of samples and were highest in quartzite and schist (both 28 percent). Lead and arsenic were present in low concentrations: the highest concentrations of lead occurred in water from quartzite (8 percent exceeded the USEPA Action Level), and arsenic was detected mostly in Triassic sedimentary rocks (9 percent exceeded the USEPA PMCL). The highest concentrations of copper occurred more frequently in quartzite rocks, and to a lesser extent were evenly distributed between ground water in gneiss, schist, and Triassic sedimentary rocks. Elevated concentrations of radon-222 and the combined radium-226/radium-228 radionuclides were common in water from quartzite and schist. Gross alpha and gross beta particle activities were elevated in water from quartzite and carbonate rocks. In contrast, elevated concentrations of uranium primarily were measured in water from Triassic sedimentary and carbonate rocks. Despite a sampling bias towards agricultural land use, only two samples indicated the presence of fecal coliforms. Samples analyzed for nutrients generally exhibited low concentrations, but about 11 percent of samples collected for nitrate exceeded the USEPA PMCL. Only one nitrite sample (less than 1 percent) exceeded the respective USEPA PMCL. Approximately 190 samples were collected for each of the three pesticides in this report: lindane, dieldrin, and diazinon. Sampling was biased towards agricultural, low-medium density residential, and wooded land uses. Approximately 95 percent of samples for each pesticide were below minimum reporting levels (MRL). Only lindane has a USEPA PMCL, and only one sample exceeded the standard. Results for dieldrin and diazinon were similar, except results for two diazinon samples where concentrations were 57.0 and 490 micrograms per liter (μg/L). Volatile organic compounds in this report were analyzed in water from 198 samples. Sampling was biased towards agricultural, low-medium density residential, and wooded land uses. Two percent of samples analyzed for trichloroethylene and less than 1 percent of samples analyzed for tetrachloroethylene exceeded their respective USEPA PMCLs (each 5.0 μg/L). No samples analyzed for 1,1,1-trichloroethane exceeded the USEPA PMCL (200 μg/L). No samples analyzed for methyl tert-butyl ether exceeded the USEPA Drinking Water Advisory (20μg/L).

Open-File Report↗

USGS2025

Groundwater hydrology, groundwater and surface-water interactions, water quality, and groundwater-flow simulations for the Wet Mountain Valley alluvial aquifer, Custer and Fremont Counties, Colorado, 2017–19

In 2017, the U.S. Geological Survey, in cooperation with the Upper Arkansas Water Conservancy District, began a study to provide a comprehensive analysis of the Wet Mountain Valley alluvial aquifer, Custer and Fremont Counties, Colorado. The study included collection of data pertaining to groundwater hydrology, groundwater and surface-water interactions, and water quality in the alluvial aquifer. In addition to providing foundational information on the hydrology of the alluvial aquifer, a numerical groundwater-flow model was developed to estimate the potential effects of additional storage of groundwater in the alluvial aquifer. Groundwater-level elevation data from 30 wells were used to estimate groundwater-flow directions in the alluvial aquifer, which were generally from the southwest to northeast, away from the Sangre de Cristo Mountains and towards perennial streams in the center of the valley. Although some seasonal variation was apparent in groundwater-level elevation records, no statistically significant seasonal trends were indicated. Statistically significant long-term trends were indicated in groundwater-level elevation records for 8 of the 30 wells, and of these wells with statistically significant trends, all but 1 indicated a negative trend of groundwater-level elevations. Spatial evaluation of wells with statistically significant negative groundwater-level elevation trends showed many are in areas of denser well drilling for domestic or other uses, indicating increasing groundwater use could potentially be causing groundwater-level elevation declines. There were instances of wells with no statistically significant groundwater-level elevation trends also located in areas of greater density of well completions. Additional investigations may be necessary to more fully characterize the processes responsible for negative groundwater-level elevation trends. Streamflow gain or loss calculations were completed for low flow in 2017–19 and for high flow in 2018 in nine reaches of streams within the study area. Stream reaches of the upper Texas Creek, upper Grape Creek, upper-middle Grape Creek, and Taylor Creek displayed consistent streamflow loss in each period from 2017 to 2019. These stream reaches represent long-term sources of recharge to the alluvial aquifer. Streamflow gain or loss varies through time in other stream reaches (lower Texas Creek, lower-middle Grape Creek, lower Grape Creek below Westcliffe, and lower Grape Creek above DeWeese Reservoir). The temporally variable behavior indicates these stream reaches may be sources of groundwater recharge or areas of groundwater discharge, likely depending on temporal dynamics between the elevation of the water table and the stream. Water-quality samples were collected from 10 groundwater wells and 10 stream sites during September through November 2019. All groundwater and stream samples were analyzed for major and trace elements and stable isotopes of water. A subset of groundwater samples was also analyzed for the environmental tracers sulfur hexafluoride, tritium, and noble gases. Comparison of water-quality results to U.S. Environmental Protection Agency drinking water-quality standards indicated no constituents exceeded primary standards for human health. Spatial evaluation of water quality indicated the concentrations of various constituents are likely controlled by groundwater and surface-water interactions and by spatial variability in bedrock geology underlying the alluvial aquifer. Specifically, streams shown to gain from groundwater had water chemistry constituent compositions similar to groundwater, whereas streams exiting the Sangre de Cristo Mountains tended to have compositions consistent with snowmelt. Groundwater geochemistry appeared to be partially controlled by oxidation-reduction processes and by proximity to igneous rocks in the Wet Mountains. Environmental tracers used to estimate groundwater age indicated all sampled groundwater contained tracers representing modern recharge (approximately less than 65 years old) but mixing of premodern recharge (approximately more than 65 years old) also occurs. Spatial evaluation of environmental tracers indicated large faults may be conduits for upwelling of older groundwater. No trends were observed in groundwater age with well depth, indicating all sampled wells are located within the zone of active groundwater flow. The presence of modern groundwater in wells with statistically significant negative groundwater-level elevation trends indicates groundwater storage depletions may be partially offset by capture of modern recharge. Repeated sampling of groundwater age would be necessary, however, to determine if any trends in groundwater age exist, which may indicate changing groundwater recharge, storage, or discharge. Additional investigations could also consider quantifying groundwater age in deeper wells to more fully define the depth of active groundwater flow. A numerical groundwater-flow model was developed to estimate components of the water budget, simulate groundwater and surface-water interactions, and evaluate the potential effects of aquifer storage and recovery. Simulated groundwater-level elevations from the calibrated groundwater-flow model are similar to the observed pattern of groundwater-level elevations with higher elevations in the western part of the study area along the Sangre de Cristo Mountains. Simulated water-budget components indicate most of the recharge to the alluvial aquifer is derived from streamflow losses, which is consistent with observations of losing streams along the mountain front. The largest groundwater discharge component of the alluvial aquifer was to streams in the center of the valley, where observations of stream gain or loss indicated the predominance of gaining conditions. Comparison of groundwater and surface-water interactions between the calibrated groundwater-flow model for 2000-19 (the base-case model) and a simulation including additional recharge, representing potential aquifer storage and recovery operations, indicated the additional recharge distributed throughout the area had minimal effects on streamflow in the nearby Grape Creek. An analysis of subregional groundwater budgets showed approximately 54 percent of the additional recharge flowed back to nearby Grape Creek, and the other 46 percent was distributed laterally into adjacent cells in the alluvial aquifer. The comparison of simulations and subregional water budget show the additional recharge did not substantially alter groundwater-level elevations or basin wide groundwater storage. Although the analysis of additional recharge provided in the numerical groundwater-flow model considers only one of many possible recharge scenarios, the model provides a useful tool that could be modified for various scenarios to understand potential effects of managed aquifer recharge.

Colorado↗

USGS2013

Red-backed vole brain promotes highly efficient in vitro amplification of abnormal prion protein from macaque and human brains infected with variant Creutzfeldt-Jakob disease agent.

Rapid antemortem tests to detect individuals with transmissible spongiform encephalopathies (TSE) would contribute to public health. We investigated a technique known as protein misfolding cyclic amplification (PMCA) to amplify abnormal prion protein (PrP TSE ) from highly diluted variant Creutzfeldt-Jakob disease (vCJD)-infected human and macaque brain homogenates, seeking to improve the rapid detection of PrP TSE in tissues and blood. Macaque vCJD PrP TSE did not amplify using normal macaque brain homogenate as substrate (intraspecies PMCA). Next, we tested interspecies PMCA with normal brain homogenate of the southern red-backed vole (RBV), a close relative of the bank vole, seeded with macaque vCJD PrP TSE . The RBV has a natural polymorphism at residue 170 of the PrP-encoding gene (N/N, S/S, and S/N). We investigated the effect of this polymorphism on amplification of human and macaque vCJD PrP TSE . Meadow vole brain (170N/N PrP genotype) was also included in the panel of substrates tested. Both humans and macaques have the same 170S/S PrP genotype. Macaque PrP TSE was best amplified with RBV 170S/S brain, although 170N/N and 170S/N were also competent substrates, while meadow vole brain was a poor substrate. In contrast, human PrP TSE demonstrated a striking narrow selectivity for PMCA substrate and was successfully amplified only with RBV 170S/S brain. These observations suggest that macaque PrP TSE was more permissive than human PrP TSE in selecting the competent RBV substrate. RBV 170S/S brain was used to assess the sensitivity of PMCA with PrP TSE from brains of humans and macaques with vCJD. PrP TSE signals were reproducibly detected by Western blot in dilutions through 10 -12 of vCJD-infected 10% brain homogenates. This is the first report showing PrP TSE from vCJD-infected human and macaque brains efficiently amplified with RBV brain as the substrate. Based on our estimates, PMCA showed a sensitivity that might be sufficient to detect PrP TSE in vCJD-infected human and macaque blood.

PLoS ONE↗

USGS2018

Phytoforensics: Trees as bioindicators of potential indoor exposure via vapor intrusion

Human exposure to volatile organic compounds (VOCs) via vapor intrusion (VI) is an emerging public health concern with notable detrimental impacts on public health. Phytoforensics, plant sampling to semi-quantitatively delineate subsurface contamination, provides a potential non-invasive screening approach to detect VI potential, and plant sampling is effective and also time- and cost-efficient. Existing VI assessment methods are time- and resource-intensive, invasive, and require access into residential and commercial buildings to drill holes through basement slabs to install sampling ports or require substantial equipment to install groundwater or soil vapor sampling outside the home. Tree-core samples collected in 2 days at the PCE Southeast Contamination Site in York, Nebraska were analyzed for tetrachloroethene (PCE) and results demonstrated positive correlations with groundwater, soil, soil-gas, sub-slab, and indoor-air samples collected over a 2-year period. Because tree-core samples were not collocated with other samples, interpolated surfaces of PCE concentrations were estimated so that comparisons could be made between pairs of data. Results indicate moderate to high correlation with average indoor-air and sub-slab PCE concentrations over long periods of time (months to years) to an interpolated tree-core PCE concentration surface, with Spearman’s correlation coefficients (ρ) ranging from 0.31 to 0.53 that are comparable to the pairwise correlation between sub-slab and indoor-air PCE concentrations (ρ = 0.55, n = 89). Strong correlations between soil-gas, sub-slab, and indoor-air PCE concentrations and an interpolated tree-core PCE concentration surface indicate that trees are valid indicators of potential VI and human exposure to subsurface environment pollutants. The rapid and non-invasive nature of tree sampling are notable advantages: even with less than 60 trees in the vicinity of the source area, roughly 12 hours of tree-core sampling with minimal equipment at the PCE Southeast Contamination Site was sufficient to delineate vapor intrusion potential in the study area and offered comparable delineation to traditional sub-slab sampling performed at 140 properties over a period of approximately 2 years.

Nebraska↗

USGS2006

Factors affecting occurrence and distribution of selected contaminants in ground water from selected areas in the Piedmont Aquifer System, Eastern United States, 1993-2003

Results of ground-water sampling from 255 wells and 19 springs in 11 studies done by the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program within the Piedmont Aquifer System (PAS) were analyzed to determine the factors affecting occurrence and distribution of selected contaminants. The contaminants, which were selected on the basis of potential human-health effects, included nitrate, pesticides, volatile organic compounds (VOCs), and radon. The PAS was subdivided on the basis of the general rock type of the aquifers into three areas for the study—crystalline, carbonate, and siliciclastic. The 11 studies were designed to areally represent an individual aquifer rock type and overall are representative of the PAS in their distribution; 7 studies are in the crystalline-rock aquifers, 3 studies are in the siliciclasticrock aquifers, and 1 study is in the carbonate-rock aquifers. Four of the studies were focused on land use, 1 in an agricultural area and 3 in urban areas. The remaining studies had wells representing a range of land-use types. Analysis of results of nitrate sampling indicated that in 8 of the 10 areas where nitrate concentrations were measured, median concentrations of nitrate were below 3 mg/L (milligrams per liter); 2 of the 10 areas had statistically significant higher median concentrations when compared to the other 8 areas. The agricultural land-use study in the carbonate-rock aquifer in the Lower Susquehanna River Basin had the highest median nitrate concentration (11 mg/L), and 60 percent of the wells sampled exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL) of 10 mg/L. The major aquifer study in the crystalline-rock aquifer of the Lower Susquehanna River Basin Study Unit had the second-highest median nitrate concentration. Nitrate concentrations were positively correlated to the percentage of agricultural land use around the well, the total input of nitrogen from all sources, dissolved oxygen concentration, lithology, depth to water, and soil-matrix characteristics. A linear regression model was used to determine that increases in the percentage of agricultural land use, the input of nitrogen from all sources, and dissolved oxygen were the most significant variables affecting increased concentration of nitrate. A logistic regression model was used to determine that those same factors were the most significant variables affecting whether or not the nitrate concentration would exceed 4 mg/L. Of the analysis of samples from 253 wells and 19 springs for 47 pesticides, no sample had a pesticide concentration that exceeded any USEPA MCL. The most frequently detected pesticide was desethyl atrazine, a degradation product of atrazine; the detection frequency was 47 percent. Other frequently detected pesticides included atrazine, metolachlor, simazine, alachlor, prometon, and dieldrin. Detection frequency was affected by the analytical reporting limits; the frequency of detection was somewhat lower when all pesticides were censored to the highest common detection limit. Source factors such as agricultural land use (for agricultural herbicides), urban land use (for insecticides), and the application rate were found to have positive statistical correlations with pesticide concentration. Transport factors such as depth to water and percentage of well-drained soils, sand, or silt typically were positively correlated with higher pesticide concentrations. Sampling for VOCs was conducted in 187 wells and 19 springs that were sampled for 59 VOCs. There were 137 detections of VOCs above the common censoring limit of 0.2 µg/L. The most frequently detected VOCs were chloroform, a trihalomethane, and methyl-tert butyl ether (MTBE), a fuel oxygenate. Seventy-nine wells had at least one VOC detected. The detections were related to land use and well depth. Kendall’s tau correlations indicated a significant positive correlation between chloroform concentration and urban land use, leaking underground storage tanks, population density, and well depth. MTBE concentrations also were positively correlated to urban land use, leaking underground storage tanks, population density, and well depth. Radon was sampled at 205 sites. The subdivisions used for analysis of other contaminants were not adequate for analysis of radon because radon varies on the basis of variations in mineralogy that are not reflected by the general lithologic categories used for the rest of the studies. Concentrations of radon were highest in areas where the crystalline-rock aquifers had felsic mineralogy, and the lowest concentrations of radon were in areas where the crystalline-rocks aquifer had mafic mineralogy. Water from wells in siliciclastic-rock aquifers had concentrations of radon lower than that in the felsic crystalline-rock aquifers. More than 90 percent of the wells sampled for radon exceeded the proposed MCL of 300 pCi/L (picoCuries per liter); however, only 13 percent of those wells had concentrations in water that exceeded the alternative maximum contaminant level (AMCL), a higher level that can be used by municipalities addressing other sources of radon exposure. Overall, concentrations of constituents were related to land-use factors for nitrate, pesticides, VOCs, and to aquifer lithology for radon. None of the 47 pesticides or 59 VOCs analyzed exceeded the MCLs where those constituents were sampled. Concentrations exceeded the MCL for nitrate in 11 percent of the wells sampled. Nearly 91 percent of the wells sampled exceeded the proposed MCL for radon. Additional sampling in selected areas would improve overall understanding of the PAS and increase the possibility of creating predictive models of ground-water quality in this area.

Alabama, Delaware, Georgia, Maryland, New Jersey, ↗

USGS1915

Springs of California

In 1903 the United States Geological Survey began an investigation of the underground water of California, generally with financial cooperation on the part of the State. Since that year ten papers on the underground water of the State have been issued by the Survey, each representing an investigation that has been completed. The field work which is to serve as the basis for two additional papers has also been done and the reports are in preparation. Investigations have been begun in two other areas in the State and their results will eventually be assembled and published. Since a period soon after the inception of the California work those responsible for its conduct have realized the desirability of a special study of the springs, particularly those which yield mineral waters and which are utilized to a greater or less extent by citizens of the State and by tourists as recreation and health resorts. It did not become practicable to begin this work until the summer of 1908, when Mr. G. A. Waring, who had assisted in some of the earlier California studies and had investigated for the Survey certain areas in southern Oregon and Washington, was assigned to the task of collecting and assembling the necessary data. California, with an area of 158,000 square miles, is the second largest State in the Union. It exhibits wide geographic diversity, since it includes the lowest area in the United States Death Valley, 276 feet below sea level and the highest Mount Whitney, 14,501 feet above the sea; and accompanying this geographic diversity there is a corresponding range in scenic effects, climate, and vegetation. The records obtained at meteorological stations in the Salton Sink indicate a maximum temperature of 130° in the shade, the highest of record within the continental United States. It is probable that minimum temperatures on the higher peaks, like Mount Whitney and Mount Shasta, approach the minimum within our boundaries. Rainfall records in the most arid sections of the southern deserts of the State represent the extreme of aridity in the United States, with averages of less than 3 inches per annum and periods of 12 months or more with only traces of rain, whereas the precipitation in northwestern California is very heavy, an annual average of close to 100 inches being recorded at a few stations in Mendocino and Del Norte counties. The immensity of the area of the State has made the collection of the field data required for the report a task of considerable magnitude, though its diversity has added greatly to the interest of the work. In the original plan it was estimated that two years of field studies would prove sufficient. Mr. Waring succeeded in visiting the more important localities during this period, although some of his examinations were, of necessity, rather cursory. In midsummer, 1910, after the completion of the field work and the assembling of the greater portion of his data in manuscript form he was called by the Government of Brazil to take charge of general water supply investigations in the northeastern arid portion of that South American republic. The task of reviewing, editing, and supplementing in some respects, the results of his studies was thus unavoidably left to others. This task was rendered light by the systematic form in which Mr. Waring's material was left. It was a matter of regret to Mr. Waring, as it has been to those associated with him, that the financial limitations which controlled his work made it impracticable to procure the large number of new analyses which are particularly important in a paper of this type, in which waters of unusual chemical characteristics are discussed. Such analyses as are available have been assembled from all possible sources and combined with those which were prepared especially in connection with this investigation. The result, although it is in some respects unsatisfactory, furnishes a basis for a general view of the characteristics of the spring waters and serves to permit, their classification in a general way. Mr. Herman Stabler has reviewed the chemical data and rearranged and interpreted the available analyses. It is hoped that the report, setting forth as it does the results of impartial observations upon one of the important present and more important prospective resources of the State, will prove of value to its citizens as well as to its visitors, and that the assembled material will not be without interest to physicians, chemists, geologists, and teachers who may have especial need for the information contained in the volume.

California↗

USGS2011

Trace elements and radon in groundwater across the United States, 1992-2003

Trace-element concentrations in groundwater were evaluated for samples collected between 1992 and 2003 from aquifers across the United States as part of the U.S. Geological Survey National Water-Quality Assessment Program. This study describes the first comprehensive analysis of those data by assessing occurrence (concentrations above analytical reporting levels) and by comparing concentrations to human-health benchmarks (HHBs). Data from 5,183 monitoring and drinking-water wells representing more than 40 principal and other aquifers in humid and dry regions and in various land-use settings were used in the analysis. Trace elements measured include aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), uranium (U), vanadium (V), and zinc (Zn). Radon (Rn) gas also was measured and is included in the data analysis. Climate influenced the occurrence and distribution of trace elements in groundwater whereby more trace elements occurred and were found at greater concentrations in wells in drier regions of the United States than in humid regions. In particular, the concentrations of As, Ba, B, Cr, Cu, Mo, Ni, Se, Sr, U, V, and Zn were greater in the drier regions, where processes such as chemical evolution, ion complexation, evaporative concentration, and redox (oxidation-reduction) controls act to varying degrees to mobilize these elements. Al, Co, Fe, Pb, and Mn concentrations in groundwater were greater in humid regions of the United States than in dry regions, partly in response to lower groundwater pH and (or) more frequent anoxic conditions. In groundwater from humid regions, concentrations of Cu, Pb, Rn, and Zn were significantly greater in drinking-water wells than in monitoring wells. Samples from drinking-water wells in dry regions had greater concentrations of As, Ba, Pb, Li, Sr, V, and Zn, than samples from monitoring wells. In humid regions, however, concentrations of most trace elements were greater in monitoring wells than in drinking-water wells; the exceptions were Cu, Pb, Zn, and Rn. Cu, Pb, and Zn are common trace elements in pumps and pipes used in the construction of drinking-water wells, and contamination from these sources may have contributed to their concentrations. Al, Sb, Ba, B, Cr, Co, Fe, Mn, Mo, Ni, Se, Sr, and U concentrations were all greater in monitoring wells than in drinking-water wells in humid regions. Groundwater from wells in agricultural settings had greater concentrations of As, Mo, and U than groundwater from wells in urban settings, possibly owing to greater pH in the agricultural wells. Significantly greater concentrations of B, Cr, Se, Ag, Sr, and V also were found in agricultural wells in dry regions. Groundwater from dry-region urban wells had greater concentrations of Co, Fe, Pb, Li, Mn, and specific conductance than groundwater from agricultural wells. The geologic composition of aquifers and aquifer geochemistry are among the major factors affecting trace-element occurrence. Trace-element concentrations in groundwater were characterized in aquifers from eight major groups based on geologic material, including (1) unconsolidated sand and gravel; (2) glacial unconsolidated sand and gravel; (3) semiconsolidated sand; (4) sandstone; (5) sandstone and carbonate rock; (6) carbonate rock; (7) basaltic and other volcanic rock; and (8) crystalline rock. The majority of groundwater samples and the largest percentages of exceedences of HHBs were in the glacial and nonglacial unconsolidated sand and gravel aquifers; in these aquifers, As, Mn, and U are the most common trace elements exceeding HHBs. Overall, 19 percent of wells (962 of 5,097) exceeded an HHB for at least one trace element. The trace elements with HHBs included in this summary were Sb, As, Ba, Be, B, Cd, Cr,

Scientific Investigations Report↗