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USGS2005

Topography and Landforms of Ecuador

EXPLANATION The digital elevation model of Ecuador represented in this data set was produced from over 40 individual tiles of elevation data from the Shuttle Radar Topography Mission (SRTM). Each tile was downloaded, converted from its native Height file format (.hgt), and imported into a geographic information system (GIS) for additional processing. Processing of the data included data gap filling, mosaicking, and re-projection of the tiles to form one single seamless digital elevation model. For 11 days in February of 2000, NASA, the National Geospatial-Intelligence Agency (NGA), the German Aerospace Center (DLR), and the Italian Space Agency (ASI) flew X-band and C-band radar interferometry onboard the Space Shuttle Endeavor. The mission covered the Earth between 60?N and 57?S and will provide interferometric digital elevation models (DEMs) of approximately 80% of the Earth's land mass when processing is complete. The radar-pointing angle was approximately 55? at scene center. Ascending and descending orbital passes generated multiple interferometric data scenes for nearly all areas. Up to eight passes of data were merged to form the final processed SRTM DEMs. The effect of merging scenes averages elevation values recorded in coincident scenes and reduces, but does not completely eliminate, the amount of area with layover and terrain shadow effects. The most significant form of data processing for the Ecuador DEM was gap-filling areas where the SRTM data contained a data void. These void areas are a result of radar shadow, layover, standing water, and other effects of terrain, as well as technical radar interferometry phase unwrapping issues. To fill these gaps, topographic contours were digitized from 1:50,000 - scale topographic maps which date from the mid-late 1980's (Souris, 2001). Digital contours were gridded to form elevation models for void areas and subsequently were merged with the SRTM data through GIS and remote sensing image-processing techniques. The data contained in this publication includes a gap filled, countrywide SRTM DEM of Ecuador projected in Universal Transverse Mercator (UTM) Zone 17 North projection, Provisional South American, 1956, Ecuador datum and a non gap filled SRTM DEM of the Galapagos Islands projected in UTM Zone 15 North projection. Both the Ecuador and Galapagos Islands DEMs are available as an ESRI Grid, stored as ArcInfo Export files (.e00), and in Erdas Imagine (IMG) file formats with a 90 meter pixel resolution. Also included in this publication are high and low resolution Adobe Acrobat (PDF) files of topography and landforms maps in Ecuador. The high resolution map should be used for printing and display, while the lower resolution map can be used for quick viewing and reference purposes.

Data Series↗

USGS1975

Interpretation, compilation and field verification procedures in the CARETS project

The production of the CARETS map data base involved the development of a series of procedures for interpreting, compiling, and verifying data obtained from remote sensor sources. Level II land use mapping from high-altitude aircraft photography at a scale of 1:100,000 required production of a photomosaic mapping base for each of the 48, 50 x 50 km sheets, and the interpretation and coding of land use polygons on drafting film overlays. CARETS researchers also produced a series of 1970 to 1972 land use change overlays, using the 1970 land use maps and 1972 high-altitude aircraft photography. To enhance the value of the land use sheets, researchers compiled series of overlays showing cultural features, county boundaries and census tracts, surface geology, and drainage basins. In producing Level I land use maps from Landsat imagery, at a scale of 1:250,000, interpreters overlaid drafting film directly on Landsat color composite transparencies and interpreted on the film. They found that such interpretation involves pattern and spectral signature recognition. In studies using Landsat imagery, interpreters identified numerous areas of change but also identified extensive areas of "false change," where Landsat spectral signatures but not land use had changed.

Delaware;Maryl;New Jersey;North Carolina;Pennsylva↗

USGS2005

Herpetofaunal Inventories of the National Parks of South Florida and the Caribbean: Volume II. Virgin Islands National Park

Amphibian declines and extinctions have been documented around the world, often in protected natural areas. Concern for this alarming trend has focused attention on the need to document all species of amphibians that occur within U.S. National Parks and to search for any signs that amphibians may be declining. This study, an inventory of amphibian species in Virgin Islands National Park, was conducted from 2001 to 2003. The goals of the project were to create a georeferenced inventory of amphibian species, use new analytical techniques to estimate proportion of sites occupied by each species, look for any signs of amphibian decline (missing species, disease, die-offs, etc.), and to establish a protocol that could be used for future monitoring efforts. Several sampling methods were used to accomplish these goals. Visual encounter surveys and anuran vocalization surveys were conducted in all habitats throughout the park to estimate the proportion of sites or proportion of area occupied (PAO) by amphibian species in each habitat. Line transect methods were used to estimate density of some amphibian species and double observer analysis was used to refine counts based on detection probabilities. Opportunistic collections were used to augment the visual encounter methods for rare species. Data were collected during four sampling periods and every major trail system throughout the park was surveyed. All of the amphibian species believed to occur on St. John were detected during these surveys. One species not previously reported, the Cuban treefrog (Osteopilus septentrionalis), was also added to the species list. That species and two others (Eleutherodactylus coqui and Eleutherodactylus lentus) bring the total number of introduced amphibians on St. John to three. We detected most of the reptile species thought to occur on St. John, but our methods were less suitable for reptiles compared to amphibians. No amphibian species appear to be in decline at this time. We found no evidence of disease or of malformations. Our surveys provide a snapshot picture of the status of the amphibian species, so continued monitoring would be necessary to determine long-term trends, but several potential threats to amphibians were identified. Invasive species, especially the Cuban treefrog, have the potential to decrease populations of native amphibians. Introduced mammalian predators are also a potential threat, especially to the reptiles of St. John, and mammalian grazers might have indirect effects on amphibians and reptiles through habitat modification. Finally, loss of habitat to development outside the park boundary could harm some important populations of amphibians and reptiles on the island.

Open-File Report↗

USGS2012

Statistical analyses to support guidelines for marine avian sampling. Final report

Interest in development of offshore renewable energy facilities has led to a need for high-quality, statistically robust information on marine wildlife distributions. A practical approach is described to estimate the amount of sampling effort required to have sufficient statistical power to identify species-specific “hotspots” and “coldspots” of marine bird abundance and occurrence in an offshore environment divided into discrete spatial units (e.g., lease blocks), where “hotspots” and “coldspots” are defined relative to a reference (e.g., regional) mean abundance and/or occurrence probability for each species of interest. For example, a location with average abundance or occurrence that is three times larger the mean (3x effect size) could be defined as a “hotspot,” and a location that is three times smaller than the mean (1/3x effect size) as a “coldspot.” The choice of the effect size used to define hot and coldspots will generally depend on a combination of ecological and regulatory considerations. A method is also developed for testing the statistical significance of possible hotspots and coldspots. Both methods are illustrated with historical seabird survey data from the USGS Avian Compendium Database. Our approach consists of five main components: 1. A review of the primary scientific literature on statistical modeling of animal group size and avian count data to develop a candidate set of statistical distributions that have been used or may be useful to model seabird counts. 2. Statistical power curves for one-sample, one-tailed Monte Carlo significance tests of differences of observed small-sample means from a specified reference distribution. These curves show the power to detect "hotspots" or "coldspots" of occurrence and abundance at a range of effect sizes, given assumptions which we discuss. 3. A model selection procedure, based on maximum likelihood fits of models in the candidate set, to determine an appropriate statistical distribution to describe counts of a given species in a particular region and season. 4. Using a large database of historical at-sea seabird survey data, we applied this technique to identify appropriate statistical distributions for modeling a variety of species, allowing the distribution to vary by season. For each species and season, we used the selected distribution to calculate and map retrospective statistical power to detect hotspots and coldspots, and map pvalues from Monte Carlo significance tests of hotspots and coldspots, in discrete lease blocks designated by the U.S. Department of Interior, Bureau of Ocean Energy Management (BOEM). 5. Because our definition of hotspots and coldspots does not explicitly include variability over time, we examine the relationship between the temporal scale of sampling and the proportion of variance captured in time series of key environmental correlates of marine bird abundance, as well as available marine bird abundance time series, and use these analyses to develop recommendations for the temporal distribution of sampling to adequately represent both shortterm and long-term variability. We conclude by presenting a schematic “decision tree” showing how this power analysis approach would fit in a general framework for avian survey design, and discuss implications of model assumptions and results. We discuss avenues for future development of this work, and recommendations for practical implementation in the context of siting and wildlife assessment for offshore renewable energy development projects.

NOAA Technical Memorandum↗

USGS2020

Small basin annual yield and percentage of snowmelt runoff in North Dakota, 1931–2016

The North Dakota hydrology manual prepared by the U.S. Department of Agriculture, Soil Conservation Service, presents methodologies primarily used for developing hydrology for onfarm conservation practices, watershed projects, Resource Conservation and Development project measures, and river basin studies. The manual includes data necessary for determining hydrologic factors and developing a design discharge for a given site and intended purpose. The U.S. Geological Survey, in cooperation with the North Dakota Natural Resources Conservation Service, developed methods to reproduce and update the annual yield maps for chapter 7 of the North Dakota hydrology manual. Annual yields, in acre-feet per square mile, for the 50- and 80-percent exceedance probabilities and expected percentage of snowmelt runoff isolines were estimated using U.S. Geological Survey streamflow data from 1931 to 2016 for 71 selected streamgages with drainage areas of 505 square miles or less. An application of a modified Maintenance of Variance Extension Type III was used to estimate missing annual streamflow volumes. An alternate expected percentage of snowmelt runoff isolines was estimated using High Plains Climatic Center precipitation and snowmelt data from 1931 to 2016 for 85 selected sites. The final expected percentage of snowmelt runoff isolines was estimated using streamflow data instead of precipitation and snowfall depth data. A snowmelt runoff seasonal period of March–May produced better isoline slopes than a November–May runoff seasonal period. Slopes of the expected percentage of snowmelt runoff isolines were sensitive to amounts of missing record. Suitable isoline slopes appeared when the missing record was set to 50 percent (43 years) and 66 percent (57 years) for the 86-year period of 1931–2016.

North Dakota↗

USGS2024

Conceptualization and simulation of groundwater flow and groundwater availability in the Boone and Roubidoux aquifers in northeastern Oklahoma, 1980–2017

Oklahoma Groundwater Law (Oklahoma Statute § 82-1020.5) requires that the Oklahoma Water Resources Board conduct hydrologic investigations to determine the maximum annual yield for the State’s groundwater basins. The Boone and Roubidoux aquifers (also known as the Springfield Plateau aquifer and Ozark aquifer, respectively) are bedrock aquifers that extend from northeastern Oklahoma into Kansas, Arkansas, and Missouri. At present (2024), the Oklahoma Water Resources Board has yet to legally issue orders for the final determination of maximum annual yields for the Boone and Roubidoux aquifers. To support determination of a maximum annual yield, the U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, developed a hydrogeologic framework, a conceptual groundwater-flow model, and a calibrated numerical groundwater-flow model for the Boone and Roubidoux aquifers. Three types of groundwater-availability scenarios were simulated by using the calibrated numerical model. These scenarios were used to (1) estimate equal-proportionate-share groundwater withdrawal rates (groundwater withdrawal applied equally over the aquifer), (2) quantify the potential effects of projected groundwater withdrawals on groundwater storage over a 50-year period, and (3) simulate the potential effects of a hypothetical 10-year drought. For the Boone aquifer, equal-proportionate-share groundwater withdrawal rates were 1.10, 0.98, and 0.96 acre-feet per acre per year for the 20-, 40-, and 50-year scenarios, respectively. For the Roubidoux aquifer, equal-proportionate-share groundwater withdrawal rates were 1.76, 1.34, and 1.25 acre-feet per acre per year for the 20-, 40-, and 50-year simulations, respectively. For the 50-year scenarios, stream seepage was minimally affected. Over the 10-year drought scenario, groundwater storage in the Boone and Roubidoux aquifers decreased by 660,451 acre-feet (6.7 percent) and 508,472 acre-feet (1.0 percent), respectively.

Oklahoma↗

USGS2024

Case definitions for wildlife diseases

Welcome to the first manual of “Case Definitions for Wildlife Diseases,” a “living” electronic publication. The plan is to add and update this manual’s case definitions periodically as warranted; thus, this manual will never be completed, and readers should download the latest versions of specific chapters (that is, definitions) when available. Constructive suggestions from readers are welcome and will help guide adjustments as this project progresses. The purpose of this manual is to provide case definitions for selected diseases of importance to wildlife in Canada and the United States. Case definitions provide standard sets of criteria for classifying the degree of certainty of a particular diagnosis and help improve surveillance data quality and comparability. Better data and standardization allow for improved data sharing, which increases geographic and species surveillance coverage and permits more robust analyses. The definitions included in this manual have been developed by veterinary pathologists, epidemiologists, and wildlife biologists primarily from the U.S. Geological Survey National Wildlife Health Center (NWHC) and Canadian Wildlife Health Cooperative (CWHC). Pathologists from each organization reviewed and finalized the definitions. Each case definition has been peer reviewed by two scientific experts before publication. This manual begins with the case definition template. This generic template includes four sections: “Individual, Place, and Time Criteria for Diagnosis and Testing,” “Field Criteria for Diagnosis,” “Laboratory Criteria for Diagnosis,” and “Epidemiological Linkage Criteria for Diagnosis” and can be used to guide development of new case definitions. Information in each section is then combined to provide an overall case classification. Disease diagnoses are classified as “Confirmed,” “Presumptive,” or “Suspected;” and evidence of a pathogen or toxin is classified as “Exposed” or “Present/Detected.” Each subsequent chapter is then a case definition for a specific disease of wildlife, and infectious and non-infectious diseases are included.

Techniques and Methods↗

USGS2019

Impacts to wildlife of wind energy siting and operation in the United States

Electricity from wind energy is a major contributor to the strategy to reduce greenhouse gas emissions from fossil fuel use and thus reduce the negative impacts of climate change. Wind energy, like all power sources, can have adverse impacts on wildlife. After nearly 25 years of focused research, these impacts are much better understood, although uncertainty remains. In this report, we summarize positive impacts of replacing fossil fuels with wind energy, while describing what we have learned and what remains uncertain about negative ecological impacts of the construction and operation of land-based and offshore wind energy on wildlife and wildlife habitat in the U.S. Finally, we propose research on ways to minimize these impacts. TO SUMMARIZE: 1 Environmental and other benefits of wind energy include near-zero greenhouse gas emissions, reductions of other common air pollutants, and little or no water use associated with producing electricity from wind energy. Various scenarios for meeting U.S. carbon emission reduction goals indicate that a four- to five-fold expansion of land-based wind energy from the current 97 gigawatts (GW) by the year 2050 is needed to minimize temperature increases and reduce the risk of climate change to people and wildlife. 2 Collision fatalities of birds and bats are the most visible and measurable impacts of wind energy production. Current estimates suggest most bird species, especially songbirds, are at low risk of population-level impacts. Raptors as a group appear more vulnerable to collisions. Population-level impacts on migratory tree bats are a concern, and better information on population sizes is needed to evaluate potential impacts to these species. Although recorded fatalities of cave-dwelling bat species are typically low at most wind energy facilities, additional mortality from collisions is a concern given major declines in these species due to white-nose syndrome (WNS). Assessments of regional and cumulative fatality impacts for birds and bats have been hampered by the lack of data from areas with a high proportion of the nation’s installed wind energy capacity. Efforts to expand data accessibility from all regions are underway, and this greater access to data along with improvements in statistical estimators should lead to improved impact assessments. 3 Habitat impacts of wind energy development are difficult to assess. An individual wind energy facility may encompass thousands of acres, but only a small percentage of the landscape within the project area is directly transformed. If a project is sited in previously undisturbed habitat, there is concern for indirect impacts, such as displacement of sensitive species. Studies to date indicate displacement of some species, but the long-term population impacts are unknown. 4 Offshore wind energy development in the U.S. is just beginning. Studies at offshore wind facilities in Europe indicate some bird and marine mammal species are displaced from project areas, but substantial uncertainty exists regarding the individual or population-level impacts of this displacement. Bird and bat collisions with offshore turbines are thought to be less common than at terrestrial facilities, but currently the tools to measure fatalities at offshore wind energy facilities are not available. The wind energy industry, state and federal agencies, conservation groups, academia, and scientific organizations have collaborated for nearly 25 years to conduct the research needed to improve our understanding of risk to wildlife and to avoid and minimize that risk. Efforts to reduce the uncertainty about wildlife risk must keep up withthe pace and scale of the need to reduce carbon emissions. This will require focusing our research priorities and increasing the rate at which we incorporate research results into the development and validation of best practices for siting and operating wind energy facilities.

Issues in Ecology↗

USGS1981

Results of a modeling workshop concerning preservation and protection of wetlands in North Dakota

In a recently signed letter, the Governor of North Dakota and the Assistant Secretary of the Interior for Fish and Wildlife and Parks charged a joint state-federal study group with examination of two separate questions: 1) mitigation for the Garrison Diversion Project; and 2) planning for long-range protection and preservation of fish and wildlife habitat in North Dakota. The cochair for this study group (the Secretary of the Interior's Field Representative, Denver, Colorado, and the Natural Resources Coordinator for North Dakota) further articulated the charge concerning the second of these two questions to include three steps: 1) development of a general plan for preservation and protection of migratory waterfowl and their associated wetland habitat; 2) a comprehensive analysis of alternative strategies, including opportunities and constraints, for achieving the goals articulated in Step 1; and 3) design of a coordinated state-federal public information program to assist in plan implementation. In order to obtain input from a variety of interests, the joint study group initiated step 2 activities with a five-day workshop in Bismarck, N. D.; December 8-12, 1980. The objectives of the workshop were: 1) to identify alternative strategies for preserving and enhancing waterfowl production habitat in North Dakota; 2) to identify opportunities and constraints associated with those alternatives; and 3) to promote communication and understanding of the implications of those alternatives for all affected parties. To achieve these objectives, the workshop utilized a group of concepts and techniques collectively known as Adaptive Environmental Assessment (AEA). Developed by Dr. C. S. Holling and his co-workers at the University of British Columbia, the AEA process involves planners, managers, scientists, and other interested parties in a structures atmosphere whose focus is the construction and examination of a computerized simulation model of the resource system under consideration. The modeling process is used to promote communication, identify pertinent issues, identify key data gaps and uncertainties, direct research efforts to fill those gaps, and explore the possible consequences of various management alternatives. The workshop, which was facilitated by the AEA Group of the U.S. Fish and Wildlife Service (FWS), was attended by approximately 25 invited participants representing a variety of interests concerned with the wetlands protection issue in North Dakota. During the week workshop participants conceptualized and constructed a computerized simulation model incorporating many of the hydrologic, agricultural, and wildlife aspects of the wetlands issue. During the process of constructing this model and examining its behavior, participants identified several interesting alternative strategies that may prove useful in an overall wetland protection program, along with a variety of constraints associated with each. Perhaps the most interesting of these alternatives revolve around the idea that there may be a variety of cases in which water can be retained on the land, with concommitant benefits both for wildlife and flood control, without detriment to agricultural productivity. Examples of this kind of activity include flooding of previously drained Type I wetlands in summer fallow areas, installation of smaller drains in Type I and III wetlands to reduce the rate at which water runs off in the spring, and use of strategically located gates in drainage channels associated with the state highway system to slow runoff and create wetland habitat. Several other alternatives discussed at the workshop are related to the notion of using available, uncommitted water supplied to enhance or create wetlands. Several cases were cited in which more certain water supplies would be useful in increasing waterfowl production or reducing disease problems, especially in dry years. Water for such purposes might come from a variety of current of proposed water development projects, both large and small scale. Finally, the potential for re-establishment of "unsuccessfully" drained (i.e., not consistently usable for agricultural purposes) wetlands was discussed at some length. There are apparently substantial acreages of such wetlands in North Dakota and a program to acquire and rehabilitate them might be of considerable utility. The workshop was thus successful in accomplishing its first two objectives--identification of alternative strategies, opportunities, and constraints. However, it would be naive to suppose that any of the alternatives discussed offers a complete, simple solution to the wetlands issue in North Dakota. The most important result of the workshop may therefore be that which was accomplished relative to the third objective--promotion of communication and understanding. It was gratifying and encouraging to see the spirit of communication and cooperation that developed by the end of the workshop. The fact that representatives of many of the interests concerned with the wetlands issue participated in an open exchange of ideas and information marks an important step forward. We believe that it is imperative that this cooperative attitude be maintained, and that there are a variety of ways in which this might be accomplished. Perhaps the simplest would be a small-scale pilot project and research effort to determine the effects of wetland maintenance on summer fallow areas. Such a research program would provide not only useful information, but an opportunity for many of the affected interests to begin working toward mutually acceptable solutions to the overall wetlands issue.

North Dakota↗

USGS2023

Characterizing historic streamflow to support drought planning in the upper Missouri River basin

This project combined tree-ring based paleo and modern climate and hydrologic research aimed at understanding the primary influences on drought risk and water reliability in basins critical for western U.S. water resources. New paleohydrologic datasets and analyses were developed and applied to contextualize future streamflow projections and address specific water management questions. These questions centered around optimizing future water management protocols for numerous objectives ranging from improving agricultural water allocation during drought while maintaining instream flows for aquatic ecosystem health, to the testing of operations across large river systems with complex infrastructure critical for downstream flood control, navigation, and hydropower generation. USGS scientists worked closely with the Bureau of Reclamation to estimate both past and future drought risk at key management locations throughout the Missouri basin, the Milk and St. Mary River system, and across the major managed river systems in the western United States. These efforts provided a roadmap for future water management strategies under changing climate and water supply conditions, which are detailed in Reclamation’s newly completed Missouri Headwaters Basin Study, the 2021 SECURE Water Act Report, and the forthcoming update of the St. Mary and Milk Rivers Basin Study. Among the major scientific findings to emerge was a new understanding of the long-term (1200-year) history of drought variability for the Missouri River, which highlighted the unusual severity of the early 2000s drought across the Rocky Mountain headwaters and adjacent high plains. By combining the extended drought record with extensive modern and paleoclimate records, we document how warming exacerbates severities of naturally occurring droughts, with recent decades defined by “hot” droughts and the 2000s (2001-2010) drought ranking as the most severe event in 1200 years. Increasingly severe drought events such as this strain already over-allocated water resources that multiple sectors of society depend heavily upon.

upper Missouri River basin↗

USGS2000

Overview of the Texas Source Water Assessment Project

The 1996 Amendments to the Safe Drinking Water Act require, for the first time, that each state prepare a source water assessment for all PWS. Previously, Federal regulations focused on sampling and enforcement with emphasis on the quality of delivered water. These Amendments emphasize the importance of protecting the source water. States are required to determine the drinking-water source, the origin of contaminants monitored or the potential contaminants to be monitored, and the intrinsic susceptibility of the source water. Under the amendments to the Act, States must create SWAP Programs. The programs must include an individual source water assessment for each public water system regulated by the State. These assessments will determine whether an individual drinking water source is susceptible to contamination. During 1997?99, TNRCC and USGS staff met as subject-matter working groups to develop an approach to conducting Source Water Susceptibility Assessments (SWSA) and a draft workplan. The draft workplan was then presented to and reviewed by various stakeholder and technical advisory groups. Comments and suggestions from these groups were considered, and a final workplan was produced and presented to the EPA. After EPA approval, work formally began on the Texas SWAP Project. The project has an expected completion date of September 2002. At that time, initial SWSA of all Texas public water supplies should be complete. Ground-water supplies can be considered susceptible if a possible source of contamination (PSOC) exists in the contributing area for the public-supply well field or spring, the contaminant travel time to the well field or spring is short, and the soil zone, vadose zone, and aquifer-matrix materials are unlikely to adequately attenuate the contaminants associated with the PSOC. In addition, particular types of land use/cover within the contributing area may cause the supply to be deemed more susceptible to contamination. Finally, detection of various classes of constituents in water from wells in the vicinity of a public supply well may indicate susceptibility of the public-supply well even though there may be no identifiable PSOC or land use activity. Surface-water supplies are by nature susceptible to contamination from both point and non-point sources. The degree of susceptibility of a PWS to contamination can vary and is a function of the environmental setting, water and wastewater management practices, and land use/cover within a water supply's contributing watershed area. For example, a PWS intake downstream from extensive urban development may be more susceptible to non-point source contamination than a PWS intake downstream from a forested, relatively undeveloped watershed. Surface-water supplies are also susceptible to contamination from point sources, which may include permitted discharges, as well as accidental spills or other introduction of contaminants.

Texas↗

USGS2010

Land Disturbance Associated with Oil and Gas Development and Effects of Development-Related Land Disturbance on Dissolved-Solids Loads in Streams in the Upper Colorado River Basin, 1991, 2007, and 2025

Oil and gas resource development in the Upper Colorado River Basin (UCRB) has increased substantially since the year 2000. The UCRB encompasses several significant oil and gas producing areas that have the potential for continued oil and gas resource development. Land disturbance associated with oil and gas resource development is caused by activities related to constructing drill pads to contain drilling and well maintenance equipment and roads to access the drill pad. Land disturbed by oil and gas development has the potential to cause increased erosion, stream degradation, habitat fragmentation and alteration, and increase public use of areas that may be environmentally sensitive. Land disturbance resulting from oil and gas resource development has not been monitored and mapped on a regional scale in the UCRB. However, information on the location and age of oil and gas wells in the UCRB is available. These data combined with geographic data analysis and modeling techniques were used to estimate the total area of disturbed land associated with oil and gas resource development in 1991 and in 2007 in the UCRB. Additional information about anticipated oil and gas development in the UCRB was used to project land disturbance to the year 2025. Results of the analysis indicate that approximately 117,500 acres (183 mi2) of total land disturbance was associated with drill pads and related roads in the UCRB in 1991. The estimated area of disturbed land associated with oil and gas development increased 53 percent to 179,400 acres (280 mi2) in 2007. Projecting oil and gas development through 2025 results in a potential near doubling of the land surface disturbance to approximately 319,300 acres (500 mi2). Estimated land disturbance for 1991 and 2007 were input to a contaminant transport model developed for the UCRB to assess the statistical significance of energy-related land disturbance to contributing dissolved solids to basin streams. The statistical assessment was an observational study based on an existing model and available water-quality monitoring data for the basin. No new data were collected for the analysis. The source coefficient calibrated for the disturbed lands associated with oil and gas development in 2007 was zero, which indicated that estimated land disturbance from oil and gas development is not statistically significant in explaining dissolved solids in UCRB streams. The lack of significance in the contaminant transport modeling framework may be due to the amount of available monitoring data, the spatial distribution of monitoring sites with respect to land disturbance, or the overall quantity of land disturbance associated with oil and gas development basin wide. Finally, dissolved-solids loads derived from natural landscapes may be similar to loads derived from lands disturbed by oil and gas resource development. The model recalibration done for this study confirms calibration results from Kenney and others (2009): the most significant contributor to dissolved solids in the UCRB is irrigated agricultural land, which covers an area substantially larger than the estimated area disturbed by oil and gas development and is subjected to artificially applied water.

Scientific Investigations Report↗

USGS2005

Non-lethal estimation of body composition of Yukon River salmon

Because of the importance of Chinook salmon to commercial and subsistence fisheries on the Yukon River, further study of the factors that may affect the success of this species and our ability to manage the fisheries is warranted. Critical to these studies is the determination of the amount of lipids (fat) stored and available to the fish as its primary energy source for migration and spawning. Recent developments of Bioelectrical Impedance Analysis (BIA) promise a simple, non-lethal means of estimating proximate composition (e.g. fat, protein, water content) for field applications with fish. The goal of the project was to develop BIA models for Chinook salmon from the Yukon River watershed that would permit the non-lethal estimation of body proximate composition for use in field studies. Our results clearly demonstrated that BIA can be used to estimate proximate composition and energy density of salmon. While some minor refinements were suggested, the methodology can be used in a wide variety of field applications. For instance, application of the BIA models to predict energy levels of fish during their migration will allow evaluation of management programs, while also yielding data that can be used to evaluate energy use along the migratory path. Correlations of energy level with ongoing tagging, radio-tracking, and genetic studies also have the potential to allow managers and scientists to understand the relationship between fat content and distance to spawning location. These models have the potential for application to this species in other river systems. They also provide tools for a variety of other scientific investigation such as: 1) differences in energy stores in spawning and recruitment success; 2) effects of global warming on migratory salmonid stocks; and 3) differences in annual flow and temperature regiments upon migratory energy costs and resulting recruitment success.

Alaska, Yukon↗

USGS2009

A water-leach procedure for estimating bioaccessibility of elements in soils from transects across the United States and Canada

An objective of the North American Soil Geochemical Landscapes Project is to provide relevant data concerning bioaccessible concentrations of elements in soil to government and other institutions undertaking environmental studies. A protocol was developed that employs a 1-g soil sample agitated overnight with 40 mL of reverse-osmosis de-ionized water for 20 h, and determination of 63 elements following three steps of centrifugation by inductively coupled plasma–atomic emission spectrometry and inductively coupled plasma–mass spectrometry the following day. Statistical summaries are presented for those 48 elements (Ag, Al, As, B, Ba, Be, Br, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, Re, S, Sb, Si, Sm, Sn, Sr, Tb, Ti, Tl, Tm, U, V, W, Y, Yb, Zn, Zr, and pH) for which <20% of their data were reported as below the detection limit. The resulting data set contains analyses for 161 A-horizon soils collected along two transects, one along the 38th parallel across the USA and the other from northern Manitoba to the USA–Mexico border. The spatial distribution of three selected elements (Ca, Cu, and Pb) along the two transects is discussed in this paper both as absolute amounts liberated by the leach and expressed as a percentage of the total, or near-total, amounts determined for the elements. The Ca data reflect broad trends in soil parent materials, their weathering, and subsequent soil development. Calcium concentrations are generally found to be lower in the older soils of the eastern USA. The Cu data are higher in the eastern half of the USA, correlating with soil organic C, with which it is sequestered. The Pb data exhibit little regional variability due to natural sources, but are influenced by anthropogenic sources. Based on the Pb results, the percentage water-extractable data demonstrate promise as a tool for identifying anthropogenic components. The soil–water partition (distribution) coefficients, K d s (L/kg), were determined and their relevance to estimating bioaccessible amounts of elements to soil fauna and flora is discussed. Finally, a possible link between W concentrations in human urine and water-extractable W levels in Nevada soils is discussed.

Applied Geochemistry↗

USGS2002

Three-dimensional hydrogeologic framework model for use with a steady-state numerical ground-water flow model of the Death Valley regional flow system, Nevada and California

The U.S. Geological Survey, in cooperation with the Department of Energy and other Federal, State, and local agencies, is evaluating the hydrogeologic characteristics of the Death Valley regional ground-water flow system. The ground-water flow system covers an area of about 100,000 square kilometers from latitude 35° to 38°15' North to longitude 115° to 118° West, with the flow system proper comprising about 45,000 square kilometers. The Death Valley regional ground-water flow system is one of the larger flow systems within the Southwestern United States and includes in its boundaries the Nevada Test Site, Yucca Mountain, and much of Death Valley. Part of this study includes the construction of a three-dimensional hydrogeologic framework model to serve as the foundation for the development of a steady-state regional ground-water flow model. The digital framework model provides a computer-based description of the geometry and composition of the hydrogeologic units that control regional flow. The framework model of the region was constructed by merging two previous framework models constructed for the Yucca Mountain Project and the Environmental Restoration Program Underground Test Area studies at the Nevada Test Site. The hydrologic characteristics of the region result from a currently arid climate and complex geology. Interbasinal regional ground-water flow occurs through a thick carbonate-rock sequence of Paleozoic age, a locally thick volcanic-rock sequence of Tertiary age, and basin-fill alluvium of Tertiary and Quaternary age. Throughout the system, deep and shallow ground-water flow may be controlled by extensive and pervasive regional and local faults and fractures. The framework model was constructed using data from several sources to define the geometry of the regional hydrogeologic units. These data sources include (1) a 1:250,000-scale hydrogeologic-map compilation of the region; (2) regional-scale geologic cross sections; (3) borehole information, and (4) gridded surfaces from a previous three-dimensional geologic model. In addition, digital elevation model data were used in conjunction with these data to define ground-surface altitudes. These data, properly oriented in three dimensions by using geographic information systems, were combined and gridded to produce the upper surfaces of the hydrogeologic units used in the flow model. The final geometry of the framework model is constructed as a volumetric model by incorporating the intersections of these gridded surfaces and by applying fault truncation rules to structural features from the geologic map and cross sections. The cells defining the geometry of the hydrogeologic framework model can be assigned several attributes such as lithology, hydrogeologic unit, thickness, and top and bottom altitudes.

California, Nevada↗

USGS2002

A three-dimensional numerical model of predevelopment conditions in the Death Valley regional ground-water flow system, Nevada and California

In the early 1990's, two numerical models of the Death Valley regional ground-water flow system were developed by the U.S. Department of Energy. In general, the two models were based on the same basic hydrogeologic data set. In 1998, the U.S. Department of Energy requested that the U.S. Geological Survey develop and maintain a ground-water flow model of the Death Valley region in support of U.S. Department of Energy programs at the Nevada Test Site. The purpose of developing this "second-generation" regional model was to enhance the knowledge an understanding of the ground-water flow system as new information and tools are developed. The U.S. Geological Survey also was encouraged by the U.S. Department of Energy to cooperate to the fullest extent with other Federal, State, and local entities in the region to take advantage of the benefits of their knowledge and expertise. The short-term objective of the Death Valley regional ground-water flow system project was to develop a steady-state representation of the predevelopment conditions of the ground-water flow system utilizing the two geologic interpretations used to develop the previous numerical models. The long-term objective of this project was to construct and calibrate a transient model that simulates the ground-water conditions of the study area over the historical record that utilizes a newly interpreted hydrogeologic conceptual model. This report describes the result of the predevelopment steady-state model construction and calibration. The Death Valley regional ground-water flow system is situated within the southern Great Basin, a subprovince of the Basin and Range physiographic province, bounded by latitudes 35 degrees north and 38 degrees 15 minutes north and by longitudes 115 and 118 degrees west. Hydrology in the region is a result of both the arid climatic conditions and the complex geology. Ground-water flow generally can be described as dominated by interbasinal flow and may be conceptualized as having two main components: a series of relatively shallow and localized flow paths that are superimposed on deeper regional flow paths. A significant component of the regional ground-water flow is through a thick Paleozoic carbonate rock sequence. Throughout the flow system, ground water flows through zones of high transmissivity that have resulted from regional faulting and fracturing. The conceptual model of the Death Valley regional ground-water flow system used for this study is adapted from the two previous ground-water modeling studies. The three-dimensional digital hydrogeologic framework model developed for the region also contains elements of both of the hydrogeologic framework models used in the previous investigations. As dictated by project scope, very little reinterpretation and refinement were made where these two framework models disagree; therefore, limitations in the hydrogeologic representation of the flow system exist. Despite limitations, the framework model provides the best representation to date of the hydrogeologic units and structures that control regional ground-water flow and serves as an important information source used to construct and calibrate the predevelopment, steady-state flow model. In addition to the hydrogeologic framework, a complex array of mechanisms accounts for flow into, through, and out of the regional ground-water flow system. Natural discharges from the regional ground-water flow system occur by evapotranspiration, springs, and subsurface outflow. In this study, evapotranspiration rates were adapted from a related investigation that developed maps of evapotranspiration areas and computed rates from micrometeorological data collected within the local area over a multiyear period. In some cases, historical spring flow records were used to derive ground-water discharge rates for isolated regional springs. For this investigation, a process-based, numerical model was developed to estimate net infiltration. This result can be used to represent recharge by assuming that water that infiltrates past the “root zone” ultimately becomes ground-water recharge. Net infiltration based on this water-balance approach, however, suggests that recharge in the region exceeds the estimated ground-water discharge for the basin by almost a factor of four. The net infiltration model contains some assumptions and was limited in regard to soil moisture, bedrock permeability, and precipitation distributions that result in these higher than expected values. Despite this limitation, the net infiltration model does provide a good starting point for estimating regional ground-water recharge in the ground-water flow model. The Death Valley regional ground-water flow system was simulated using a three-dimensional steady-state model that incorporated a nonlinear least-squares regression technique to estimate selected model parameters. The numerical modeling program MODFLOW-2000 was used in creating a finite-difference model consisting of 194 rows, 160 columns, and 15 layers. The grid cells were oriented north-south and were of uniform size, with side dimensions of 1,500 meters. The layers span thicknesses of 50 to 300 meters. The model grid encompasses about 70,000 square kilometers. The required initial model parameter values were supplied by discretization of the three-dimensional hydrogeologic framework model and digital representations of the remaining conceptual model components. The three-dimensional simulation and corresponding sensitivity analysis supported the hypothesis of interactions between a relatively shallow local and subregional flow system and a deeper dominant regional system controlled by the carbonate aquifer. During calibration of the model, techniques available in MODFLOW-2000 allowed for estimation of a series of parameters that provided a best fit to observed hydraulic heads and flows. Numerous conceptual models were evaluated to test the validity of various interpretations about the flow system. Only those conceptual model changes contributing to a significant improvement in model fit, as indicated by a reduction in the sum of squared errors, were retained in the final optimized model. The final model was evaluated to assess the likely accuracy of simulated results by comparing measured and expected quantities with simulated values. Evaluation of the model indicates that although the model is clearly an improvement on previous representations of the flow system, there is an indication of important uncertainties and model error.

California, Nevada↗

USGS2007

Metallogeny of Mesoproterozoic sedimentary rocks in Idaho and Montana - Studies by the Mineral Resources Program, U.S. Geological Survey, 2004-2007

Preface By J.Michael O'Neill The major emphasis of this project was to extend and refine the known Mesoproterozoic geologic and metallogenic framework of the region along and adjacent to the Idaho-Montana boundary north of the Snake River Plain. The Mesoproterozoic metasedimentary rocks in this part of east-central Idaho host important Cu-Co-Au stratabound mineral resources as well as younger, epigenetic hydrothermal, sulfide base-metal mineral deposits. Two tasks of this study were to more accurately understand and portray the character and origin of cobalt-copper-gold deposits that compose the Idaho cobalt belt and specifically to analyze ore mineralogy and metallogenesis within the Blackbird mining district in the central part of the belt. Inasmuch as the cobalt belt is confined to the Mesoproterozoic Lemhi Group strata of east-central Idaho, geologic investigations were also undertaken to determine the relationship between strata of the Lemhi Group and the more extensive, noncobalt-bearing, Belt-Purcell Supergroup strata to the north and northwest. Abrupt lateral differences in the character and thickness of stratigraphic units in the Mesoproterozoic Lemhi Basin may indicate differential sedimentation in contemporaneous fault-bounded subbasins. It is suggested that northeast-trending basement faults of the Great Falls tectonic zone controlled development of the subbasins. O'Neill and others (chapter A, this volume) document a second major basement fault in this area, the newly recognized northwest-striking Great Divide megashear, a zone 1-2 km wide of left-lateral strike-slip faults active during Mesoproterozoic sedimentation and bounding the Cu-Co belt on the northwest. The megashear is a crustal-scale tectonic feature that separates Lemhi Group strata from roughly coeval Belt-Purcell strata to the north and northwest in Montana and northern Idaho. The results of numerous geologic investigations of the Cu- and Co-bearing Mesoproterozoic rocks of east-central Idaho are integrated and summarized by Bookstrom and others (chapter B, this volume). In particular, their field investigations and analysis of evidence and previous arguments for synsedimentary versus epigenetic mineral deposit types, both of which have been postulated by earlier workers, led them to conclude that both processes were likely instrumental in forming the ore deposits of the Blackbird district. Finally, this report supplies new data on isotopic ratios of sulfur, oxygen, carbon, and helium in minerals associated with cobalt-bearing ores of the cobalt belt. Slack (chapter C, this volume) identified several previously unrecognized rare-earth-element minerals in Blackbird ores: monazite (Ce,La,Y,Th)PO4, xenotime (YPO4), allanite (CaCe)2(Al,Fe)3Si3O12(OH), and gadolinite (Be2FeY2Si2O10). Light rare-earth elements reside mostly in monazite, whereas yttrium and heavy rare-earth minerals reside mostly in xenotime. Dated monazite, which in the Blackbird district is interstitial to cobaltite, is Cretaceous. This date brings into question the otherwise geologically convincing interpretation of Blackbird ores as being of Mesoproterozoic age and synsedimentary origin. This volume consists of three summary articles: A. Great Divide megashear, Montana, Idaho, and Washington: An intraplate crustal-scale shear zone recurrently active since the Mesoproterozoic by J. Michael O'Neill, Edward T. Ruppel, and David A. Lopez B. Blackbird Fe-Cu-Co-Au-REE deposits by Arthur A. Bookstrom, Craig A. Johnson, Gary P. Landis, and Thomas P. Frost C. Geochemical and mineralogical studies of sulfide and iron oxide deposits in the Idaho cobalt belt by John F. Slack

Idaho, Montana↗

USGS2020

Characterization of water-quality and bed-sediment conditions in Currituck Sound, North Carolina, prior to the Mid-Currituck Bridge construction, 2011–18

The North Carolina Turnpike Authority plans to improve transportation in the Currituck Sound area by constructing a two-lane bridge—the Mid-Currituck Bridge—across Currituck Sound from the mainland to the Outer Banks, North Carolina. The results of the final environmental impact statement for the project indicate potential water-quality and habitat effects for Currituck Sound associated with the bridge and roadway improvements. The primary objective of this study is to characterize water-quality conditions and bed-sediment chemistry in the vicinity of the planned Mid-Currituck Bridge, providing a baseline for evaluating the potential effects of bridge construction and bridge deck runoff on environmental conditions in Currituck Sound. From August 2011 through January 2018, water-quality and bed-sediment samples were collected from five sampling stations along the planned bridge alignment. Samples were analyzed for numerous characteristics, including physical properties and constituents that are associated with bridge deck stormwater runoff and are important to estuarine waters. The analyzed characteristics included dissolved oxygen, pH, specific conductance, turbidity, suspended solids, metals, nutrients, semi-volatile organic compounds, bacteria, chlorophyll a, cyanotoxins, and phytoplankton abundance. The most common constituents with concentrations above applicable State and Federal water-quality thresholds included chlorophyll a, pH, turbidity, Enterococci, and pentachlorophenol. Few bed-sediment samples had constituent concentrations that exceeded applicable sediment-quality guidelines. Results indicated that water sampled along the planned bridge alignment was well mixed vertically and horizontally but varied temporally. Seasonal changes in water quality best explained the variations in water-quality conditions in Currituck Sound during the study. Wind conditions also influenced water levels and water-quality conditions. Turbidity and concentrations of particle-associated constituents tended to be higher when water levels were lower, possibly reflecting the increased resuspension of bottom materials from wind-driven wave action.

North Carolina↗