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USGS2016

Summary of U.S. Geological Survey studies conducted in cooperation with the Citizen Potawatomi Nation, central Oklahoma, 2011–14

The U.S. Geological Survey conducted hydrologic studies and published three U.S. Geological Survey scientific investigations reports in cooperation with the Citizen Potawatomi Nation from 2011 to 2014 to characterize the quality and quantity of water resources. The study areas of those reports consisted of approximately 960 square miles in parts of three counties in central Oklahoma. This study area has multiple abundant sources of water, being underlain by three principal aquifers (alluvial/terrace, Central Oklahoma, and Vamoosa-Ada), being bordered by two major rivers (North Canadian and Canadian), and having several smaller drainages including the Little River in the central part of the study area and Salt Creek in the southeastern part of the study area. The Central Oklahoma aquifer (also referred to as the “Garber-Wellington aquifer”) underlies approximately 3,000 square miles in central Oklahoma in parts of Cleveland, Logan, Lincoln, Oklahoma, and Pottawatomie Counties and much of the study area. Water from these aquifers is used for municipal, industrial, commercial, agricultural, and domestic supplies. Much of the water in the study area is of good quality; however, in some parts of this area water quality was impaired by very hard surface water and groundwater, large chloride concentrations in some smaller streams, relatively large concentrations of nitrogen and phosphorus nutrients and large counts of fecal-indicator bacteria in the North Canadian River, and uranium concentrations that exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level of 30 micrograms per liter for public water supplies in water samples collected from a small number of wells. Most stream-water samples collected from the Little River by the U.S. Geological Survey in 2012–13 had dissolved solids concentrations exceeding the U.S. Environmental Protection Agency Secondary Maximum Contaminant Level for public water supplies of 500 milligrams per liter. Larger numbers of organic compounds were measured in water samples collected from the North Canadian River than the Little River. Numerical groundwater-flow models were created to characterize flow systems in aquifers underlying this study area and areas of particular interest within the study area. Those models were used to estimate sustainable groundwater yields from parts of the North Canadian River alluvial aquifer, characterize groundwater/surface-water interactions, and estimate the effects of a 10-year simulated drought on streamflows and water levels in alluvial and bedrock aquifers. Pumping of wells at the Iron Horse Industrial Park was estimated to cause negligible infiltration of water from the adjoining North Canadian River. A 10-year simulated drought of 50 percent of normal recharge was tested for the period 1990–2000. For this period, the total amount of groundwater in storage was estimated to decrease by 8.6 percent in the North Canadian River alluvial aquifer and approximately 0.2 percent in the Central Oklahoma aquifer, and groundwater flow to streams was estimated to decrease by 28–37 percent. This volume of groundwater loss showed that the Central Oklahoma aquifer is a bedrock aquifer that has relatively low rates of recharge from the land surface. The simulated drought decreased simulated streamflow, composed of base flow, in the North Canadian River at Shawnee, Okla., which did not recover to predrought conditions until the relatively wet year of 2007 after the simulated drought period.

Oklahoma↗
USGS2016

Adjusted peak-flow frequency estimates for selected streamflow-gaging stations in or near Montana based on data through water year 2011: Chapter D in Montana StreamStats

The climatic conditions of the specific time period during which peak-flow data were collected at a given streamflow-gaging station (hereinafter referred to as gaging station) can substantially affect how well the peak-flow frequency (hereinafter referred to as frequency) results represent long-term hydrologic conditions. Differences in the timing of the periods of record can result in substantial inconsistencies in frequency estimates for hydrologically similar gaging stations. Potential for inconsistency increases with decreasing peak-flow record length. The representativeness of the frequency estimates for a short-term gaging station can be adjusted by various methods including weighting the at-site results in association with frequency estimates from regional regression equations (RREs) by using the Weighted Independent Estimates (WIE) program. Also, for gaging stations that cannot be adjusted by using the WIE program because of regulation or drainage areas too large for application of RREs, frequency estimates might be improved by using record extension procedures, including a mixed-station analysis using the maintenance of variance type I (MOVE.1) procedure. The U.S. Geological Survey, in cooperation with the Montana Department of Transportation and the Montana Department of Natural Resources and Conservation, completed a study to provide adjusted frequency estimates for selected gaging stations through water year 2011. The purpose of Chapter D of this Scientific Investigations Report is to present adjusted frequency estimates for 504 selected streamflow-gaging stations in or near Montana based on data through water year 2011. Estimates of peak-flow magnitudes for the 66.7-, 50-, 42.9-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities are reported. These annual exceedance probabilities correspond to the 1.5-, 2-, 2.33-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively. The at-site frequency estimates were adjusted by weighting with frequency estimates from RREs using the WIE program for 438 selected gaging stations in Montana. These 438 selected gaging stations (1) had periods of record less than or equal to 40 years, (2) represented unregulated or minor regulation conditions, and (3) had drainage areas less than about 2,750 square miles. The weighted-average frequency estimates obtained by weighting with RREs generally are considered to provide improved frequency estimates. In some cases, there are substantial differences among the at-site frequency estimates, the regression-equation frequency estimates, and the weighted-average frequency estimates. In these cases, thoughtful consideration should be applied when selecting the appropriate frequency estimate. Some factors that might be considered when selecting the appropriate frequency estimate include (1) whether the specific gaging station has peak-flow characteristics that distinguish it from most other gaging stations used in developing the RREs for the hydrologic region; and (2) the length of the peak-flow record and the general climatic characteristics during the period when the peak-flow data were collected. For critical structure-design applications, a conservative approach would be to select the higher of the at-site frequency estimate and the weighted-average frequency estimate. The mixed-station MOVE.1 procedure generally was applied in cases where three or more gaging stations were located on the same large river and some of the gaging stations could not be adjusted using the weighted-average method because of regulation or drainage areas too large for application of RREs. The mixed-station MOVE.1 procedure was applied to 66 selected gaging stations on 19 large rivers. The general approach for using mixed-station record extension procedures to adjust at-site frequencies involved (1) determining appropriate base periods for the gaging stations on the large rivers, (2) synthesizing peak-flow data for the gaging stations with incomplete peak-flow records during the base periods by using the mixed-station MOVE.1 procedure, and (3) conducting frequency analysis on the combined recorded and synthesized peak-flow data for each gaging station. Frequency estimates for the combined recorded and synthesized datasets for 66 gaging stations with incomplete peak-flow records during the base periods are presented. The uncertainties in the mixed-station record extension results are difficult to directly quantify; thus, it is important to understand the intended use of the estimated frequencies based on analysis of the combined recorded and synthesized datasets. The estimated frequencies are considered general estimates of frequency relations among gaging stations on the same stream channel that might be expected if the gaging stations had been gaged during the same long-term base period. However, because the mixed-station record extension procedures involve secondary statistical analysis with accompanying errors, the uncertainty of the frequency estimates is larger than would be obtained by collecting systematic records for the same number of years in the base period.

Montana↗
USGS2010

Saltcedar (Tamarix spp.) and Russian Olive (Elaeagnus angustifolia) in the Western United States-A Report on the State of the Science

The Salt Cedar and Russian Olive Control Demonstration Act of 2006 (Public Law 109-320) directs the Department of the Interior to submit a report to Congress that includes an assessment of several issues surrounding these two nonnative trees, now dominant components of the vegetation along many rivers in the Western United States. This report was published in 2010 as a U.S. Geological Survey Scientific Investigations Report (available online at http://pubs.usgs.gov/sir/2009/5247). The report was produced through a collaborative effort led by the Bureau of Reclamation and U.S. Geological Survey, with critical contributions from the U.S. Department of Agriculture and from university researchers. The document synthesizes the state of the science and key research needs on the following topics related to management of saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) in the Western United States: their distribution and abundance (extent); the potential for water savings associated with controlling these species; considerations related to wildlife use of saltcedar and Russian olive habitat and restored habitats; methods of control and removal; possible utilization of dead biomass following control and removal; and approaches and challenges associated with site revegetation or restoration. A concluding chapter discusses possible long-term management strategies, potentially useful field-demonstration projects, and a planning process for on-the-ground projects involving removal of saltcedar and Russian olive.

Fact Sheet↗
USGS2016

Methods for estimating peak-flow frequencies at ungaged sites in Montana based on data through water year 2011: Chapter F in Montana StreamStats

The U.S. Geological Survey (USGS), in cooperation with the Montana Department of Natural Resources and Conservation, completed a study to update methods for estimating peak-flow frequencies at ungaged sites in Montana based on peak-flow data at streamflow-gaging stations through water year 2011. The methods allow estimation of peak-flow frequencies (that is, peak-flow magnitudes, in cubic feet per second, associated with annual exceedance probabilities of 66.7, 50, 42.9, 20, 10, 4, 2, 1, 0.5, and 0.2 percent) at ungaged sites. The annual exceedance probabilities correspond to 1.5-, 2-, 2.33-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence intervals, respectively. Regional regression analysis is a primary focus of Chapter F of this Scientific Investigations Report, and regression equations for estimating peak-flow frequencies at ungaged sites in eight hydrologic regions in Montana are presented. The regression equations are based on analysis of peak-flow frequencies and basin characteristics at 537 streamflow-gaging stations in or near Montana and were developed using generalized least squares regression or weighted least squares regression. All of the data used in calculating basin characteristics that were included as explanatory variables in the regression equations were developed for and are available through the USGS StreamStats application (http://water.usgs.gov/osw/streamstats/) for Montana. StreamStats is a Web-based geographic information system application that was created by the USGS to provide users with access to an assortment of analytical tools that are useful for water-resource planning and management. The primary purpose of the Montana StreamStats application is to provide estimates of basin characteristics and streamflow characteristics for user-selected ungaged sites on Montana streams. The regional regression equations presented in this report chapter can be conveniently solved using the Montana StreamStats application. Selected results from this study were compared with results of previous studies. For most hydrologic regions, the regression equations reported for this study had lower mean standard errors of prediction (in percent) than the previously reported regression equations for Montana. The equations presented for this study are considered to be an improvement on the previously reported equations primarily because this study (1) included 13 more years of peak-flow data; (2) included 35 more streamflow-gaging stations than previous studies; (3) used a detailed geographic information system (GIS)-based definition of the regulation status of streamflow-gaging stations, which allowed better determination of the unregulated peak-flow records that are appropriate for use in the regional regression analysis; (4) included advancements in GIS and remote-sensing technologies, which allowed more convenient calculation of basin characteristics and investigation of many more candidate basin characteristics; and (5) included advancements in computational and analytical methods, which allowed more thorough and consistent data analysis. This report chapter also presents other methods for estimating peak-flow frequencies at ungaged sites. Two methods for estimating peak-flow frequencies at ungaged sites located on the same streams as streamflow-gaging stations are described. Additionally, envelope curves relating maximum recorded annual peak flows to contributing drainage area for each of the eight hydrologic regions in Montana are presented and compared to a national envelope curve. In addition to providing general information on characteristics of large peak flows, the regional envelope curves can be used to assess the reasonableness of peak-flow frequency estimates determined using the regression equations.

Montana↗
USGS2006

Guidelines and standard procedures for continuous water-quality monitors: Station operation, record computation, and data reporting

The U.S. Geological Survey uses continuous water-quality monitors to assess the quality of the Nation's surface water. A common monitoring-system configuration for water-quality data collection is the four-parameter monitoring system, which collects temperature, specific conductance, dissolved oxygen, and pH data. Such systems also can be configured to measure other properties, such as turbidity or fluorescence. Data from sensors can be used in conjunction with chemical analyses of samples to estimate chemical loads. The sensors that are used to measure water-quality field parameters require careful field observation, cleaning, and calibration procedures, as well as thorough procedures for the computation and publication of final records. This report provides guidelines for site- and monitor-selection considerations; sensor inspection and calibration methods; field procedures; data evaluation, correction, and computation; and record-review and data-reporting processes, which supersede the guidelines presented previously in U.S. Geological Survey Water-Resources Investigations Report WRIR 00-4252. These procedures have evolved over the past three decades, and the process continues to evolve with newer technologies.

Techniques and Methods↗
USGS2002

Studies by the U.S. Geological Survey in Alaska, 2000

The collection of eight papers that follow continue the series of U.S. Geological Survey (USGS) investigative reports in Alaska under the broad umbrella of the geologic sciences. The series presents new and sometimes-preliminary findings that are of interest to earth scientists in academia, government, and industry; to land and resource managers; and to the general public. Reports presented in Studies by the U.S. Geological Survey in Alaska cover a broad spectrum of topics from various parts of the State (fig. 1), serving to emphasize the diversity of USGS efforts to meet the Nation's needs for earth-science information in Alaska. The papers in this volume are organized under the topics Geologic Framework, Resources, and Environment and Climate. This organization is intended to reflect the scope and objectives of current USGS geologic programs in Alaska. In particular, Geologic Framework studies provide background information that is the scientific basis for present and future earth-science investigations.

Alaska↗
USGS2018

Assessment of environmental flows in the middle Verde River watershed, Arizona

This report summarizes analyses of middle Verde River watershed environmental flows detailed in U.S. Geological Survey Scientific Investigations Report 2017-5100, “Preliminary synthesis and assessment of environmental flows in the middle Verde River watershed, Arizona," by N.V. Paretti, A.M.D. Brasher, S.L. Pearlstein, D.M. Skow, B. Gungle, and B.D. Garner.

Arizona↗
USGS2015

Data regarding hydraulic fracturing distributions and treatment fluids, additives, proppants, and water volumes applied to wells drilled in the United States from 1947 through 2010

Comprehensive, published, and publicly available data regarding the extent, location, and character of hydraulic fracturing in the United States are scarce. The objective of this data series is to publish data related to hydraulic fracturing in the public domain. The spreadsheets released with this data series contain derivative datasets aggregated temporally and spatially from the commercial and proprietary IHS database of U.S. oil and gas production and well data (IHS Energy, 2011). These datasets, served in 21 spreadsheets in Microsoft Excel (.xlsx) format, outline the geographical distributions of hydraulic fracturing treatments and associated wells (including well drill-hole directions) as well as water volumes, proppants, treatment fluids, and additives used in hydraulic fracturing treatments in the United States from 1947 through 2010. This report also describes the data—extraction/aggregation processing steps, field names and descriptions, field types and sources. An associated scientific investigation report (Gallegos and Varela, 2014) provides a detailed analysis of the data presented in this data series and comparisons of the data and trends to the literature.

Data Series↗
USGS1995

Trace metals and major and rare earth elements in cuttings from five high-temperature wells in the northwest region of The Geysers, California, vapor-dominated geothermal system

Temperatures within the main vapor-dominated steam reservoir at The Geysers geothermal field generally are in the range 238°C to 244°C. A few deep wells in the northwestern part of the field have penetrated beneath this reservoir into a second vapor-dominated reservoir where temperatures are >315°C, while vapor pressure remains nearly constant at about 35.9 bars (Walters et al., 1992). Vapor-dominated reservoirs generally are thought to operate like heat pipes in which steam formed near the base of the system convects upward (along with other gases, such as CC>2 and H2S), while liquid that has condensed from steam near the top of the reservoir counterflows downward (White et al., 1971). To the extent that this steam condensate carries H2S in solution, it may dissolve gold from the surrounding rock during the counterflow. Re-evaporation of the down-flowing condensate and precipitation of dissolved material might occur at the base of the upper reservoir where there is a relatively sharp increase in temperature while vapor pressure remains nearly constant. In addition, brine that once was present throughout the system (Moore, 1992) may have deposited a variety of ore minerals when and where boiling was vigorous during the transition from previous hot water-dominated to present-day vapor-dominated conditions. The investigation reported here was a geochemical reconnaissance survey looking for evidence of accumulation of Au and other metals in the transition zone between the two reservoirs. The petrology of the cuttings was not examined as part of the investigation.

Open-File Report↗
USGS2000

Geohydrology of the shallow aquifers in the Greeley-Nunn area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and vitality of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The water resources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources. and the Colorado Water Conservation Board.

Hydrologic Atlas↗
USGS2000

Geohydrology of the shallow aquifers in the Fort Collins-Loveland area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and existence of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The waterresources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

Hydrologic Atlas↗
USGS2000

Geohydrology of the shallow aquifers in the Fort Lupton-Gilcrest area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area seep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may be prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot be mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and existence of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) are the results of FRIRP water-resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The water resources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

Colorado↗
USGS2000

Geohydrology of the shallow aquifers in the Boulder-Longmont area, Colorado

Urban areas commonly rely on ground water for at least part of the municipal water supply, and as population increases, urban areas expand and require larger volumes of water. However, the expansion of an urban area can reduce ground-water availability. This may occur through processes of depletion (withdrawal of most of the available ground water), degradation (chemicals used in the urban area keep into the ground and contaminate the ground water), and preemption (cost or restrictions on pumping ground water from under extensively urbanized areas may he prohibitive). Thus, a vital natural resource needed to support the growth of an urban area and its infrastructure can become less available because of growth itself. The diminished availability of natural resources caused by expansion of urban areas is not unique to water resources. For example, large volumes of aggregate (sand and gravel) are used in concrete and asphalt to build and maintain the infrastructure (buildings, roads, airports, and so forth) of an urban area. Yet, mining of aggregate commonly is preempted by urban expansion; for example, it cannot he mined from under a subdivision. Energy resources such as coal, oil, and natural gas likewise are critical to the growth and existence of an urban area but may become less available as an urban area expands and preempts mining and drilling. In 1996, the U.S. Geological Survey began work on a national initiative designed to provide information on the availability of those natural resources (water, minerals, energy, and biota) that are critical to maintaining the Nation's infrastructure or that may become less available because of urban expansion. The initiative began with a 3-year demonstration project to develop procedures for assessing resources and methods for interpreting and publishing information in digital and traditional paper formats. The Front Range urban corridor of Colorado was chosen as the demonstration area (fig. 1), and the project was titled the Front Range Infrastructure Resources Project (FRIRP). This report and those of Robson (1996), Robson and others (1998), and Robson and others (2000a, 2000b, 2000c) (fig. 1) are the results of FRIRP water resources investigations; reports pertaining to geology, minerals, energy, biota, and cartography of the FRIRP are published separately. The water-resources studies of the FRIRP were undertaken in cooperation with the Colorado Department of Natural Resources, Division of Water Resources, and the Colorado Water Conservation Board.

Hydrologic Atlas↗
USGS1995

Listings of model input and selected output values for the simulation of ground-water flow near Los Alamos, North-central New Mexico

This report contains listings of model input and selected output values for the simulation of ground-water flow near Los Alamos, north- central New Mexico. This simulation was developed by the U.S. Geological Survey in cooperation with Los Alamos National Laboratory (Frenzel, P.F., 1995, Geohydrology and simulation of ground-water flow near Los Alamos, north-central New Mexico: U.S. Geological Survey Water-Resources Investigations Report 95-4091). The simulation used the U.S. Geological Survey modular flow model code (McDonald, M.G., and Harbaugh, A.W., 1988, A modular three-dimensional finite-difference ground-water flow model: Techniques of Water-Resources Investigations of the United States Geological Survey, book 6, chap. A1). The listings in this report are in compressed format on a 1.44-megabyte IBM-PC1 compatible floppy disk. Software is included for decompression to ASCII format.

Open-File Report↗
USGS2015

Bioaccumulation trends of arsenic and antimony in a freshwater ecosystem affected by mine drainage

We compared As and Sb bioaccumulation and biomagnification when these metalloids co-occurred at varying environmental concentrations in a stream and wetlands near a contaminated mine site in Idaho (USA). We measured As and Sb concentrations in water and substrate samples, and in tissues of organisms representing several trophic levels. Bioaccumulation of both As and Sb was observed in stream organisms with the following trend of bio-diminution with increasing trophic level: primary producers > tadpoles > macroinvertebrates > trout. We also note reductions in metalloid concentrations in one of two stream remediation reaches engineered within the past 17 years to ameliorate metalloid contamination in the stream. Several wetlands contained thick microbial mats and were highly populated with boreal toad tadpoles that fed on them. The mats were extremely contaminated (up to 76 564 mg kg –1 As and 675 mg kg –1 Sb) with amorphous As- and Sb-bearing minerals that we interpret as biogenic precipitates from geomicrobiological As- and Sb-cycling. Ingested mat material provided a direct source of metalloids to tadpoles, and concentrations of 3867 mg kg –1 (As) and 375 mg kg –1 (Sb) reported here represent the highest whole body As and Sb levels ever reported in living tadpoles. The bulk of tadpole metalloid burden remained in the gut despite attempts to purge the tadpoles prior to analysis. This study adds to a number of recent investigations reporting bioaccumulation, but not biomagnification, of As and Sb in food webs. Moreover, our results suggest that tadpoles, in particular, may be more resistant to metalloid contamination than previously assumed.

Environmental Chemistry↗
USGS2010

Computer simulation of reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout

This report describes the application of a computer model to simulate reservoir depletion and oil flow from the Macondo well following the Deepwater Horizon blowout. Reservoir and fluid data used for model development are based on (1) information released in BP's investigation report of the incident, (2) information provided by BP personnel during meetings in Houston, Texas, and (3) calibration by history matching to shut-in pressures measured in the capping stack during the Well Integrity Test. The model is able to closely match the measured shut-in pressures. In the simulation of the 86-day period from the blowout to shut in, the simulated reservoir pressure at the well face declines from the initial reservoir pressure of 11,850 pounds per square inch (psi) to 9,400 psi. After shut in, the simulated reservoir pressure recovers to a final value of 10,300 psi. The pressure does not recover back to the initial pressure owing to reservoir depletion caused by 86 days of oil discharge. The simulated oil flow rate declines from 63,600 stock tank barrels per day just after the Deepwater Horizon blowout to 52,600 stock tank barrels per day just prior to shut in. The simulated total volume of oil discharged is 4.92 million stock tank barrels. The overall uncertainty in the simulated flow rates and total volume of oil discharged is estimated to be + or - 10 percent.

Open-File Report↗