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At least 1,765 records · Page 98Linked to original sources
USGS2021

Improved Automated Identification and Mapping of Iron Sulfate Minerals, Other Mineral Groups, and Vegetation using Landsat 8 Operational Land Imager Data, San Juan Mountains, Colorado, and Four Corners Region

Multispectral remote sensing data acquired by the Landsat 8 Operational Land Imager (OLI) sensor were analyzed using a new, automated technique to generate a map of exposed mineral and vegetation groups in the western San Juan Mountains, Colo., and the Four Corners Region of the United States. Band ratio results were combined into displayed mineral and vegetation groups using Boolean algebra. New analysis logic has been implemented to exploit the coastal aerosol band in Landsat 8 OLI data and identify concentrations of iron sulfate minerals. These may indicate the presence of near-surface pyrite, which can be a potential nonpoint source of acid rock drainage. Zoned occurrences of iron sulfate minerals in areas surrounding and down gradient of known sources of pyrite have been mapped using this technique. They show high correlation with occurrences of jarosite-bearing mineral assemblages, as mapped using airborne imaging spectrometer data and supporting field verification surveys. Mapping the occurrence of iron sulfate minerals produced by the weathering and oxidation of pyrite in exposed hydrothermally altered rocks can also provide an important indicator of the genetic environment of alteration and the associated mineral deposit type. The automated analysis methodology is being employed to rapidly and cost-effectively generate maps of large regions of the United States in support of U.S. Geological Survey mineral resource and mineral-environmental assessments. This map, which includes the ERDAS IMAGINE thematic raster format in the data release, has been attributed by pixel value with mineral and vegetation group classification data, which can be queried in most image processing and GIS software packages.

Colorado, Utah↗
USGS2023

Surficial geologic map of the Owlshead Mountains 30' x 60' quadrangle, Inyo and San Bernardino Counties, California

The surficial geologic map of the Owlshead Mountains 30' x 60' quadrangle depicts the distribution and characteristics of surficial-deposit materials and neotectonic deformation for an area of approximately 5,000 square kilometers (km 2 ) located in the western Basin and Range Province of eastern California. The map represents a new compilation of the surficial geology that encompasses deposits within the late Pliocene to Quaternary. The map is based primarily on new mapping conducted between 2001 and 2009. Map compilation was supported by field observations distributed across the map area, combined with reference to several published and unpublished mapping sources that mostly emphasized neotectonic deformation. The surficial-deposit units included in the map follow a classification scheme that systematically denotes depositional process, relative age, and any secondary sedimentologic or morphologic characteristics. Identification, correlation, and age estimation of map units are based primarily on the relative degree of development of certain time-dependent characteristics such as surface morphology, including local dissection and surface preservation, surface clast modification, and degree of soil development; these characteristics are implicitly incorporated into unit designations. The map represents a detailed and regionally uniform synthesis of the late Neogene geology for this large area that provides a framework applicable to many interpretative studies, such as regional patterns of deposition and dissection; surface drainage development and evolution; and the distribution, style, and timing of neotectonic deformation.

California↗
USGS2005

Geochemistry of Red Mountain Creek, Colorado, under low-flow conditions, August 2002

Red Mountain Creek, an acid mine drainage stream in southwestern Colorado, was the subject of a synoptic study conducted in August 2002. During the synoptic study, a solution containing lithium chloride was injected continuously to allow for the calculation of streamflow using the tracer-dilution method. Synoptic water-quality samples were collected from 48 stream sites and 29 inflow locations along a 5.4-kilometer study reach. Data from the study provide profiles of pH, concentration, and mass load with a high degree of spatial resolution. Despite the presence of 10 circumneutral inflows, pH remained below 3.4 at all stream sites. Concentration profiles indicate that dissolved concentrations of aluminum, cadmium, copper, lead, and zinc exceed chronic aquatic-life standards established by the State of Colorado along the entire study reach. Comparison of total recoverable and dissolved concentrations suggests that most constituents were transported conservatively. Exceptions to this pattern include arsenic, iron, molybdenum, and vanadium, four constituents that were subject to precipitation and(or) sorption reactions as the addition of a circumneutral tributary resulted in a slight increase in instream pH. Evaluation of data from the 29 inflow locations indicates a sharp contrast between the east and west sides of the watershed; inflows from the east side have high constituent concentrations and acidic pH, whereas inflows from the west side have lower concentrations and generally higher pH. Loading profiles, the product of streamflow and concentration, are used to rank potential sources of metals and acidity within the watershed. Four sources account for 83, 72, 70, 69, 64, and 61 percent of the aluminum, iron, arsenic, zinc, copper, and cadmium loading within the study reach, respectively. All four sources appear to be the result of surface inflows that have been affected by mining activities. The relatively small number of major sources and the fact that they are attributable to surface inflows are two factors that may facilitate effective remediation.

Colorado↗
USGS2005

Surface water-quality and water-quantity data from selected urban runoff-monitoring sites at the Rocky Mountain Arsenal, Commerce City, Colorado, water years 1988-2004

The U.S. Geological Survey has monitored the quality and quantity of streamflow at the Rocky Mountain Arsenal (RMA) northeast of Denver, Colorado, since the early 1990s in cooperation with the U.S. Army. This report, prepared in cooperation with the U.S. Fish and Wildlife Service, documents existing surface-water-quality conditions on the RMA. All RMA water-quality data for the Irondale Gulch and First Creek Basins adjacent to and on the RMA were reviewed. Where applicable, water-quality data were compared to State standards established by the Colorado Department of Public Health and Environment. At both the Havana Interceptor below 56th Avenue gaging station and the Uvalda Interceptor below 56th Avenue gaging station, all of the dissolved-oxygen concentrations met the State standard requiring at least 5.0 milligrams per liter (mg/L) of dissolved oxygen for the protection of aquatic life. In contrast, the dissolved-oxygen concentrations at the Peoria Interceptor below 56th Avenue gage commonly were less than 5.0 mg/L. Excluding one suspect concentration of 1.6 mg/L, the dissolved-oxygen concentrations for the First Creek Basin ranged from 4.2 to 12.6 mg/L. Excluding the one suspect value, three dissolved-oxygen concentrations failed to meet the State standard of 5.0 mg/L at the First Creek below Buckley Road site. At the Peoria Interceptor below 56th Avenue site, all pH values were within the range specified by the State standard (6.50-8.99). Results of seven sampling events at the Havana Interceptor below 56th Avenue gaging station indicated a pH greater than or equal to 9 (pH values of 9 or greater exceed the upper limit of the standard). No sampling events indicated a pH less than 6.50. Results from one sampling event at the Uvalda Interceptor below 56th Avenue indicated pH values outside the range specified by the State standard. The concentrations obtained for chloride, magnesium, and sodium generally were below 200 mg/L at all three Irondale Gulch monitoring stations for the entire period of record, but there were a few sampling events at each of these sites where much higher concentrations for these analytes were obtained. The median concentrations for calcium, magnesium, and sodium generally were higher at the First Creek below Buckley Road site than in the three Irondale Gulch sites, while the 90th percentile and maximum concentrations for magnesium and sodium generally were higher at the three Irondale Gulch sites than at the First Creek below Buckley Road site. The urban runoff flowing onto the RMA had low concentrations and few, if any, detections for most organic contaminants. Part of the reason for low detections of organic contaminants may be in how the samples are collected. The existing surface-water sampling program was not designed specifically to target storm runoff and therefore does not characterize water quality for all hydrologic regimes, most notably storm runoff. As a result, the existing data may not adequately represent potential contaminant transport onto the RMA. In addition, during stormwater-runoff events, the sites examined for this report frequently are subject to sharp increases in discharge, and just as quickly the discharge rapidly recedes. These types of transient flow events make water-quality sampling difficult, and none of the sites have a safe place to sample the higher flows that occur in any given year. As a result, most of the surface-water-quality samples were collected after the flow had decreased substantially from the peak flow, which may have transported much of the chemical contaminant load through the system. Thus, little is known about the water quality during the critical initial stormwater-runoff period when contaminants are most likely to be mobilized and transported through the stormwater conveyances past the locations where gaging stations are located.

Colorado↗
USGS2008

Analysis of Conservative Tracer Tests in the Bullfrog, Tram, and Prow Pass Tuffs, 1996 to 1998, Yucca Mountain, Nye County, Nevada

To evaluate the potential for transport of radionuclides in ground water from the proposed high-level nuclear-waste repository at Yucca Mountain, Nevada, conservative (nonsorbing) tracer tests were conducted among three boreholes, known as the C-hole Complex, and values for transport (or flow) porosity, storage (or matrix) porosity, longitudinal dispersivity, and the extent of matrix diffusion were obtained. The C-holes are completed in a sequence of Miocene tuffaceous rock, consisting of nonwelded to densely welded ash-flow tuff with intervals of ash-fall tuff and volcaniclastic rocks, covered by Quaternary alluvium. The lower part of the tuffaceous-rock sequence includes the Prow Pass, Bullfrog, and Tram Tuffs of the Crater Flat Group. The rocks are pervaded by tectonic and cooling fractures. Paleozoic limestone and dolomite underlie the tuffaceous rocks. Four radially convergent and one partially recirculating conservative (nonsorbing) tracer tests were conducted at the C-hole Complex from 1996 to 1998 to establish values for flow porosity, storage porosity, longitudinal dispersivity, and extent of matrix diffusion in the Bullfrog and Tram Tuffs and the Prow Pass Tuff. Tracer tests included (1) injection of iodide into the combined Bullfrog-Tram interval; (2) injection of 2,6 difluorobenzoic acid into the Lower Bullfrog interval; (3) injection of 3-carbamoyl-2-pyridone into the Lower Bullfrog interval; and (4) injection of iodide and 2,4,5 trifluorobenzoic acid, followed by 2,3,4,5 tetrafluorobenzoic acid, into the Prow Pass Tuff. All tracer tests were analyzed by the Moench single- and dual-porosity analytical solutions to the advection-dispersion equation or by superposition of these solutions. Nonlinear regression techniques were used to corroborate tracer solution results, to obtain optimal parameter values from the solutions, and to quantify parameter uncertainty resulting from analyzing two of the three radially convergent conservative tracer tests conducted in the Bullfrog and Tram intervals. Longitudinal dispersivity values in the Bullfrog and Tram Tuffs ranged from 1.83 to 2.6 meters, flow-porosity values from 0.072 to 0.099, and matrix-porosity values from 0.088 to 0.19. The flow-porosity values indicate that the pathways between boreholes UE-25 c#2 and UE-25 c#3 in the Bullfrog and Tram intervals are not connected well. Tracer testing in the Prow Pass interval indicates different transport characteristics than those obtained in the Bullfrog and Tram intervals. In the Prow Pass Tuff, longitudinal dispersivity was 0.27 meter, flow porosity was 4.5 ? 10?4, and matrix porosity was 0.01. This indicates that the flow network in the Prow Pass is dominated by interconnected fractures, whereas in the Bullfrog and Tram, the flow network is dominated by discontinuous fractures with connecting segments of matrix.

Scientific Investigations Report↗
USGS2008

Elements in Mud and Snow in the Vicinity of the DeLong Mountain Regional Transportation System Road, Red Dog Mine, and Cape Krusenstern National Monument, Alaska, 2005-06

A small number of mud, road bed soil, and snow samples were collected in 2005 and 2006 to assess metal concentrations and loadings to areas adjacent to the DeLong Mountain Regional Transportation System (DMTS) road in northwest Alaska. The DMTS road is used by large trucks to transport lead and zinc concentrates from Red Dog Mine to the shipping facility at Red Dog Port; it traverses 32 kilometers of land in Cape Krusenstern National Monument (CAKR). Mud collected in the summer of 2005 from wheel-wells of two passenger vehicles used for transport between Red Dog Mine and the port facility were enriched in cadmium, lead, and zinc by factors of about 200 to 800 as compared with mud collected from a vehicle stationed in Kotzebue, Alaska, whereas DMTS road bed soil samples were enriched by factors of 6 to 12. Thus, as of 2005, dispersal of mine ore wastes or concentrates by vehicles appeared to remain a potential source of metals along the DMTS road. Compared to snow samples obtained near a gravel road located near Kotzebue, Alaska, metal loadings estimated from individual snow samples collected in CAKR in April 2006 near three creeks, 13 to 50 meters from the road, were greater by factors of 13 to 316 for cadmium, 28 to 589 for lead, and 8 to 195 for zinc. When averaged for all three creek locations, mean loadings of cadmium, lead, and zinc calculated from snow samples collected at a nominal distance of 15 meters to the north of the road were 0.63, 34, and 89 milligrams of metal per square meter, respectively. Variability of particulate and metal loadings between individual samples and the three creek locations probably was affected by localized meteorological conditions and micro-topography on the snow drift and scour patterns, but road orientation on attainable truck speeds also might have been a factor. Results indicated that the ?port effect?, previously attributed to fugitive metal-enriched dusts stemming from concentrate transfer operations at the port facility, was not necessarily an important factor affecting spatial differences of metals deposition in snow along the road in CAKR during winter 2005?06. The average metal content of particulates in 2005?06 snow samples was slightly less than that of snow samples collected by the U.S. Geological Survey in CAKR at three near-road locations in April 2003. Mean metals concentrations in 2006 snow particulates were about three times greater than in the road bed soils that were sampled in 2005; however, the fraction of annual metals loadings occurring in winter as compared to the remainder of the year was not readily determined by these data. Although procedures have been implemented in recent years to reduce the quantities of metal-enriched fugitive dusts, particulates dispersed near the road during the winter of 2005?06 were enriched in metals and these particulates contributed considerable metal loadings to the nearby terrain.

Scientific Investigations Report↗
USGS2008

Effects of forest harvesting on ecosystem health in the headwaters of the New York City Water Supply, Catskill Mountains, New York

The effects of forest clearcutting and selective harvesting on forest soils, soil and stream water chemistry, forest regrowth, and aquatic communities were studied in four small headwater catchments. This research was conducted to identify the sensitivity of forested ecosystems to forest disturbance in the northeastern United States. The study area was in the headwaters of the Neversink Reservoir watershed, part of the New York City water supply system, in the Catskill Mountains of southeastern New York. Two sub-catchments of the Shelter Creek watershed were selectively harvested, one in its northern half and one more heavily in its southern half in 1995?96, the Dry Creek watershed was clearcut in the winter of 1996?97, and the Clear Creek watershed was left undisturbed and monitored as a control site. Monitoring was conducted from 4 years before the harvests until 4 years after the harvests. Clearcutting caused a large release of nitrate (NO3-) from watershed soils and a concurrent release of inorganic monomeric aluminum (Alim), which is toxic to some aquatic biota. The increased soil NO3- concentrations measured after the harvest could be completely accounted for by the decrease in nitrogen (N) uptake by watershed trees, rather than an increase in N mineralization and nitrification. The large increase in stream water NO3- and Alim concentrations caused 100-percent mortality of caged brook trout (Salvelinus fontinalis) during the first year after the clearcut and adversely affected macroinvertebrate communities for 2 years after the harvest. Nutrient uptake and biomass accumulation increased in uncut mature trees after the two selective harvests. There was no increase in stream-water NO3- or Alim concentrations, and so there were no adverse affects on macroinvertebrate or trout communities. The amount of tree biomass that can be removed without causing a sharp increase in stream-water NO3- and Alim stream-water concentrations is unknown, but probably depends on the history of forest-disturbance and acid deposition and the level of soil acidification. Results of this study indicate that macroinvertebrate and brook trout communities were sensitive to clearcutting and that deer browsing may affect water quality by suppressing forest regeneration and nutrient uptake. Further studies of selective harvests could identify the harvesting threshold below which changes in water quality and soil chemistry are minimized, and nutrient retention is maximized, thus reducing the damage that logging can inflict on stream and aquatic communities.

New York↗
USGS2008

Assessment of metals exposure and sub-lethal effects in voles and small birds captured near the DeLong Mountain Regional Transportation System Road, Cape Krusenstern National Monument, Alaska, 2006

Voles (n=6) and small ground-nesting birds (n=12) were live-captured near the DeLong Mountain Regional Transportation System haul road in Cape Krusenstern National Monument in northwest Alaska in 2006 to assess metals exposure and sub-lethal biological effects. Similar numbers of animals were captured from a reference site in southern Cape Krusenstern National Monument for comparison. Histopathological examination of selected organs, blood analysis, and analysis for aluminum, barium, cadmium, lead, and zinc concentrations in liver and blood samples were performed. Voles and small birds captured from near the haul road had about 20 times greater blood and liver lead concentrations and about 3 times greater cadmium concentrations when compared to those from the reference site. Barium and zinc tissue concentrations of animals collected from different sites were not remarkably different, and aluminum concentrations were below the reporting limits in most samples. There was no clear evidence of serious sub-lethal biological effects such as lesions in internal organs or DNA damage in blood in any of the animals. Accordingly, blood and liver lead concentrations in animals captured near the haul road generally were less than tissue concentration thresholds associated with serious biological effects reported from other studies; however, subtle effects resulting from lead exposure, such as the suppression of the activity of certain enzymes, cannot be ruled out for those animals nearest the haul road. Notably, liver lead concentrations of voles and small birds at the reference location were considerably less than those previously reported for similar animals at reference sites in other parts of the United States, Canada, and Europe. Results from this reconnaissance-level study indicate that voles and small birds inhabiting this area are not suffering serious biological effects as a result of metals exposure; however, continued monitoring of lead and other metals is recommended because of uncertainties noted and because biological effects thresholds might be approached if exposure levels were to increase.

Scientific Investigations Report↗
USGS2009

DayCent-Chem simulations of ecological and biogeochemical processes of eight mountain ecosystems in the United States

Atmospheric deposition of nitrogen (N) and sulfur (S) cause complex responses in ecosystems, from fertilization to forest ecosystem decline, freshwater eutrophication to acidification, loss of soil base cations, and alterations of disturbance regimes. DayCent-Chem, an ecosystem simulation model that combines ecosystem nutrient cycling and plant dynamics with aqueous geochemical equilibrium calculations, was developed to address ecosystem responses to combined atmospheric N and S deposition. It is unique among geochemically-based models in its dynamic biological cycling of N and its daily timestep for investigating ecosystem and surface water chemical response to episodic events. The model was applied to eight mountainous watersheds in the United States. The sites represent a gradient of N deposition across locales, from relatively pristine to N-saturated, and a variety of ecosystem types and climates. Overall, the model performed best in predicting stream chemistry for snowmelt-dominated sites. It was more difficult to predict daily stream chemistry for watersheds with deep soils, high amounts of atmospheric deposition, and a large degree of spatial heterogeneity. DayCent-Chem did well in representing plant and soil carbon and nitrogen pools and fluxes. Modeled stream nitrate (NO 3 - ) and ammonium (NH 4 + ) concentrations compared well with measurements at all sites, with few exceptions. Simulated daily stream sulfate (SO 4 2- ) concentrations compared well to measured values for sites where SO 4 2- deposition has been low and where SO 4 2- adsorption/desorption reactions did not seem to be important. The concentrations of base cations and silica in streams are highly dependent on the geochemistry and weathering rates of minerals in each catchment, yet these were rarely, if ever, known. Thus, DayCent-Chem could not accurately predict weathering products for some catchments. Additionally, few data were available for exchangeable soil cations or the magnitude of base cation deposition as a result of dry and fog inputs. The uncertainties related to weathering reactions, deposition, soil cation exchange capacity, and groundwater contributions influenced how well the simulated acid neutralizing capacity (ANC) and pH estimates compared to observed values. Daily discharge was well represented by the model for most sites. The chapters of this report describe the parameterization for each site and summarize model results for ecosystem variables, stream discharge, and stream chemistry. This intersite comparison exercise provided insight about important and possibly not well understood processes.

Scientific Investigations Report↗
USGS2010

Demography of the Pryor Mountain wild horses, 1993-2007

Wild horses (Equus caballus) at Pryor Mountain were studied by direct observation from 1993 through 2007. All horses present were individually identifiable on the basis of coat coloration, head and leg markings, gender, and band associations. Of the 609 horses either present prior to foaling in 1993 or born since, ages were precisely known for 491 (observed as a foal). Ages for 52 horses were estimated through tooth eruption and wear patterns, and for the remaining 66 horses through body size, morphology, and anecdotal evidence concerning when they were present on the range. At varying intensities, never less than 30 days per year, all horses were inventoried and their band associations noted. Foals were paired with dams based on observations of attachment during the early days and weeks of life. Year of death was determined by identification of the carcass where possible. In the absence of finding a carcass, an animal that was not observed for 2 years was considered to have died in the year that it went missing. Animals that were removed from the herd and mares that were part of a contraception study were excluded from calculations of survival and foaling rates, respectively, as appropriate. The average prefoaling population over the 15 years of the study was 148.8 animals (range = 120-187), and the annual foal crop averaged 32.1 (range = 23-40). Large removals (19-60 animals) in four years helped maintain the herd at this level; apparent growth rate (calculated as though removals had not occurred) was 9.6 percent annually (? = 1.096, range = 0.977-1.220). This annual growth rate is relatively low compared to that for many western horse herds, at least in part because of a decline in foal survival. Sex ratio of the foal crop varied widely among years, but pooled across years did not differ from 50:50. Sex ratio in the herd changed mostly as a result of removals. The average age of both males and females in the herd increased during the course of the study. Annual survival of males did not differ from that of females, nor did gender affect annual survival of foals. Pooled across years, ages, and sexes, the annual survival rate was 0.899. Annual foal survival rate was 0.697 and declined through time, with a tendency toward recovery in 2005-2007. Foal survival was higher in larger bands, but did not differ between foals born to primiparous and multiparous mares. A few 2-year-old mares produced foals; foaling rate (excluding contracepted mares and foals they produced) increased through age 10, remained high through age 15, and declined thereafter. Overall foaling rate for mares =3 years of age was 0.576 foals per mare, with no apparent trend during the period of our study. Foaling rate in years following gathers was somewhat lower than in other years. There was a positive relation between foaling rate and band size. Primiparous mares were somewhat less likely to foal in the following year than were multiparous mares. Most stallions that acquired a harem did so at age 5 or 6, and the average age of harem stallions increased during our study. Most harems had 1-3 mares =2 years of age, but harem size varied with age of the stallion, increasing through about age 11 and declining thereafter. About 6 percent of bands had a satellite stallion (=5 years of age), but the mean number of mares did not differ between single- and multistallion bands. Most stallions left their natal band at age 2 or 3, but 17 percent remained with their natal band until age 4 or 5. Foal survival rate was positively related to precipitation, suggesting a possible link to forage production and availability mediated through mare fitness. There also was evidence for density-dependent population regulation, as both population growth rate and survival rate were negatively correlated with population size from the previous year. These and other factors were not sufficient to stabilize the population during our period of study, however, as evidenced by the necess

Scientific Investigations Report↗
USGS2011

Lithogeochemistry of mineralized and altered rock samples from the northern Talkeetna Mountains, south-central Alaska

Mineralized and altered rock samples collected from the northern Talkeetna Mountains, Alaska, were analyzed by two different inductively coupled plasma atomic-emission spectrometry (ICP-AES) methods for as many as 44 elements; by fire assay and either direct-coupled plasma (DCP) or atomic absorption spectrophotometry (AAS) for gold (Au); by cold vapor atomic absorption (CVAA) for mercury (Hg); and by irradiated neutron activation analysis (INAA) for tungsten (W). The analytical results showed that some samples contain high values of multiple elements and may be potential indicators of hydrothermal mineralization in the area.

Alaska↗
USGS2011

Assessment of potential migration of radionuclides and trace elements from the White Mesa uranium mill to the Ute Mountain Ute Reservation and surrounding areas, southeastern Utah

In 2007, the Ute Mountain Ute Tribe requested that the U.S. Environmental Protection Agency and U.S. Geological Survey conduct an independent evaluation of potential offsite migration of radionuclides and selected trace elements associated with the ore storage and milling process at an active uranium mill site near White Mesa, Utah. Specific objectives of this study were (1) to determine recharge sources and residence times of groundwater surrounding the mill site, (2) to determine the current concentrations of uranium and associated trace elements in groundwater surrounding the mill site, (3) to differentiate natural and anthropogenic contaminant sources to groundwater resources surrounding the mill site, (4) to assess the solubility and potential for offsite transport of uranium-bearing minerals in groundwater surrounding the mill site, and (5) to use stream sediment and plant material samples from areas surrounding the mill site to identify potential areas of offsite contamination and likely contaminant sources.

Utah↗
USGS2012

Simulation of climate change in San Francisco Bay Basins, California: Case studies in the Russian River Valley and Santa Cruz Mountains

As a result of ongoing changes in climate, hydrologic and ecologic effects are being seen across the western United States. A regional study of how climate change affects water resources and habitats in the San Francisco Bay area relied on historical climate data and future projections of climate, which were downscaled to fine spatial scales for application to a regional water-balance model. Changes in climate, potential evapotranspiration, recharge, runoff, and climatic water deficit were modeled for the Bay Area. In addition, detailed studies in the Russian River Valley and Santa Cruz Mountains, which are on the northern and southern extremes of the Bay Area, respectively, were carried out in collaboration with local water agencies. Resource managers depend on science-based projections to inform planning exercises that result in competent adaptation to ongoing and future changes in water supply and environmental conditions. Results indicated large spatial variability in climate change and the hydrologic response across the region; although there is warming under all projections, potential change in precipitation by the end of the 21st century differed according to model. Hydrologic models predicted reduced early and late wet season runoff for the end of the century for both wetter and drier future climate projections, which could result in an extended dry season. In fact, summers are projected to be longer and drier in the future than in the past regardless of precipitation trends. While water supply could be subject to increased variability (that is, reduced reliability) due to greater variability in precipitation, water demand is likely to steadily increase because of increased evapotranspiration rates and climatic water deficit during the extended summers. Extended dry season conditions and the potential for drought, combined with unprecedented increases in precipitation, could serve as additional stressors on water quality and habitat. By focusing on the relationship between soil moisture storage and evapotranspiration pressures, climatic water deficit integrates the effects of increasing temperature and varying precipitation on basin conditions. At the fine-scale used for these analyses, this variable is an effective indicator of the areas in the landscape that are the most resilient or vulnerable to projected changes. These analyses have shown that regardless of the direction of precipitation change, climatic water deficit is projected to increase, which implies greater water demand to maintain current agricultural resources or land cover. Fine-scale modeling provides a spatially distributed view of locations in the landscape that could prove to be resilient to climatic changes in contrast to locations where vegetation is currently living on the edge of its present-day bioclimatic distribution and, therefore, is more likely to perish or shift to other dominant species under future warming. This type of modeling and the associated analyses provide a useful means for greater understanding of water and land resources, which can lead to better resource management and planning.

California↗
USGS2012

Bankfull-channel geometry and discharge curves for the Rocky Mountains Hydrologic Region in Wyoming

Regional curves relate bankfull-channel geometry and bankfull discharge to drainage area in regions with similar runoff characteristics and are used to estimate the bankfull discharge and bankfull-channel geometry when the drainage area of a stream is known. One-variable, ordinary least-squares regressions relating bankfull discharge, cross-sectional area, bankfull width, and bankfull mean depth to drainage area were developed from data collected at 35 streamgages in or near Wyoming. Watersheds draining to these streamgages are within the Rocky Mountains Hydrologic Region of Wyoming and neighboring states.

Colorado;Montana;Wyoming↗
USGS2014

Status and understanding of groundwater quality in the Klamath Mountains study unit, 2010: California GAMA Priority Basin Project

Groundwater quality in the Klamath Mountains (KLAM) study unit was investigated as part of the Priority Basin Project of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program. The study unit is located in Del Norte, Humboldt, Shasta, Siskiyou, Tehama, and Trinity Counties. The GAMA Priority Basin Project is being conducted by the California State Water Resources Control Board in collaboration with the U.S. Geological Survey (USGS) and the Lawrence Livermore National Laboratory. The GAMA Priority Basin Project was designed to provide a spatially unbiased, statistically robust assessment of the quality of untreated (raw) groundwater in the primary aquifer system. The assessment is based on water-quality data and explanatory factors for groundwater samples collected in 2010 by the USGS from 39 sites and on water-quality data from the California Department of Public Health (CDPH) water-quality database. The primary aquifer system was defined by the depth intervals of the wells listed in the CDPH water-quality database for the KLAM study unit. The quality of groundwater in the primary aquifer system may be different from that in the shallower or deeper water-bearing zones; shallow groundwater may be more vulnerable to surficial contamination. This study included two types of assessments: (1) a status assessment , which characterized the status of the current quality of the groundwater resource by using data from samples analyzed for volatile organic compounds, pesticides, and naturally occurring inorganic constituents, such as major ions and trace elements, and (2) an understanding assessment , which evaluated the natural and human factors potentially affecting the groundwater quality. The assessments were intended to characterize the quality of groundwater resources in the primary aquifer system of the KLAM study unit, not the quality of treated drinking water delivered to consumers by water purveyors. Relative-concentrations (sample concentrations divided by the health- or aesthetic-based benchmark concentrations) were used for evaluating groundwater quality for those constituents that have Federal or California regulatory or non-regulatory benchmarks for drinking-water quality. A relative-concentration greater than (>) 1.0 indicates a concentration greater than a benchmark, and a relative-concentration less than or equal to (≤) 1.0 indicates a concentration less than or equal to a benchmark. Relative-concentrations of organic constituents were classified as “high” (relative-concentration > 1.0), “moderate” (0.1 < relative-concentration ≤ 1.0), or “low” (relative-concentration ≤ 0.1). For inorganic constituents, the boundary between low and moderate relative-concentration was set at 0.5. Aquifer-scale proportion was used in the status assessment as the primary metric for evaluating regional-scale groundwater quality. High aquifer-scale proportion is defined as the percentage of the area of the primary aquifer system with a relative-concentration greater than 1.0 for a particular constituent or class of constituents; percentage is based on an areal rather than a volumetric basis. Moderate and low aquifer-scale proportions were defined as the percentages of the primary aquifer system with moderate and low relative-concentrations, respectively. The KLAM study unit includes more than 8,800 square miles (mi 2 ), but only those areas near the sampling sites, about 920 mi 2 , are included in the areal assessment of the study unit. Two statistical approaches—grid-based and spatially weighted—were used to evaluate aquifer-scale proportions for individual constituents and classes of constituents. To confirm this methodology, 90 percent confidence intervals were calculated for the grid-based high aquifer-scale proportions and were compared to the spatially weighted results, which were found to be within these confidence intervals in all cases. Grid-based results were selected for use in the status assessment unless, as was observed in a few cases, a grid-based result was zero and the spatially weighted result was not zero, in which case, the spatially weighted result was used. The status assessment showed that inorganic constituents with human-health benchmarks were detected at high relative-concentrations in 2.6 percent of the primary aquifer system and at moderate relative-concentrations in 10 percent of the system. The high aquifer-scale proportion for inorganic constituents mainly reflected the high aquifer-scale proportions of boron. Inorganic constituents with secondary maximum contaminant levels were detected at high relative-concentrations in 13 percent of the primary aquifer system and at moderate relative-concentrations in 10 percent of the system. The constituents present at high relative-concentrations included iron and manganese. Organic constituents with human-health benchmarks were not detected at high relative-concentrations, but were detected at moderate relative-concentrations in 1.9 percent of the primary aquifer system. The 1.9 percent reflected a spatially weighted moderate aquifer-scale proportion for the gasoline additive methyl tert-butyl ether. Of the 148 organic constituents analyzed, 14 constituents were detected. Only one organic constituent had a detection frequency of greater than 10 percent—the trihalomethane, chloroform. The second component of this study, the understanding assessment , identified the natural and human factors that may have affected the groundwater quality in the KLAM study unit by evaluating statistical correlations between water-quality constituents and potential explanatory factors. The potential explanatory factors evaluated were aquifer lithology, land use, hydrologic conditions, depth, groundwater age, and geochemical conditions. Results of the statistical evaluations were used to explain the occurrence and distribution of constituents in the KLAM study unit. Groundwater age distribution (modern, mixed, or pre-modern), redox class (oxic, mixed, or anoxic), and dissolved oxygen concentration were the explanatory factors that best explained occurrence patterns of the inorganic constituents. High concentrations of boron were found to be associated with groundwater classified as mixed or pre-modern with respect to groundwater age. Boron was also negatively correlated to dissolved oxygen and positively correlated to specific conductance. Iron and manganese concentrations were strongly associated with low dissolved oxygen concentrations, anoxic and mixed redox classifications, and pre-modern groundwater. Specific conductance concentrations were found to be related to pre-modern groundwater, low dissolved oxygen concentrations, and high pH. Chloroform was selected for additional evaluation in the understanding assessment because it was detected in more than 10 percent of wells sampled in the KLAM study unit. Septic tank density was the only explanatory factor that was found to relate to chloroform concentrations.

California↗
USGS2016

Geology and mineral resources of the Sheldon-Hart Mountain National Wildlife Refuge Complex (Oregon and Nevada), the Southeastern Oregon and North-Central Nevada, and the Southern Idaho and Northern Nevada (and Utah) Sagebrush Focal Areas: Chapter B in Mineral resources of the Sagebrush Focal Areas of Idaho, Montana, Nevada, Oregon, Utah, and Wyoming

Summary The U.S. Department of the Interior has proposed to withdraw approximately 10 million acres of Federal lands from mineral entry (subject to valid existing rights) from 12 million acres of lands defined as Sagebrush Focal Areas (SFAs) in Idaho, Montana, Nevada, Oregon, Utah, and Wyoming (for further discussion on the lands involved see Scientific Investigations Report 2016–5089–A). The purpose of the proposed action is to protect the greater sage-grouse ( Centrocercus urophasianus ) and its habitat from potential adverse effects of locatable mineral exploration and mining. The U.S. Geological Survey Sagebrush Mineral-Resource Assessment (SaMiRA) project was initiated in November 2015 and supported by the Bureau of Land Management to (1) assess locatable mineral-resource potential and (2) to describe leasable and salable mineral resources for the seven SFAs and Nevada additions. This chapter summarizes the current status of locatable, leasable, and salable mineral commodities and assesses the potential of selected locatable minerals in lands proposed for withdrawal that span the Nevada, Oregon, Idaho, and Utah borders. In this report, the four study areas evaluated were (1) the Sheldon-Hart Mountain National Wildlife Refuge Complex SFA in Washoe County, Nevada, and Harney and Lake Counties, Oregon; (2) the Southeastern Oregon and North-Central Nevada SFA in Humboldt County, Nevada, and Harney and Malheur Counties, Oregon; (3) the Southern Idaho and Northern Nevada SFA in Cassia, Owyhee, and Twin Falls Counties, Idaho, Elko County, Nevada, and Box Elder County, Utah; and (4) the Nevada additions in Humboldt and Elko Counties, Nevada.

Idaho, Nevada, Oregon, Utah↗
USGS2018

Simulation of potential groundwater recharge for the glacial aquifer system east of the Rocky Mountains, 1980–2011, using the Soil-Water-Balance Model

An understanding of the spatial and temporal extent of groundwater recharge is critical for many types of hydrologic assessments involving water quality, contaminant transport, ecosystem health, and sustainable use of groundwater. Annual potential groundwater recharge was simulated at a 1-kilometer resolution with the Soil-Water-Balance (SWB) model for the glacial aquifer system east of the Rocky Mountains, from central Montana east to Maine, for calendar years 1980–2011. The SWB model used high resolution meteorological, land cover, and soil hydrology datasets that are nationally consistent and publicly available. The SWB model computed daily potential groundwater recharge as precipitation in excess of interception, runoff, evapotranspiration, and soil-water storage capacity. Daily potential recharge values within each year of the simulation were summed to produce annual potential recharge rates. Potential recharge as described in this report is water that infiltrates vertically below the plant rooting zone and is assumed to reach the water table. The calibrated SWB model in this report is called the glacial SWB model. Model calibration assumed that the area contributing to groundwater discharge equaled the surface watershed. The model was calibrated to stream base flows from 39 watersheds throughout the model domain that had hydrologic conditions appropriate for hydrograph separation. Base flows were calculated from daily streamflow records with the HYSEP local minimum hydrograph separation method The glacial SWB model reproduced the mean annual base-flow calibration targets well; the Nash-Sutcliffe efficiency coefficient was 0.94, and the root mean squared error was 1.28 inches per year. The glacial SWB model provides insight into the spatial and temporal variability in potential annual recharge across the glacial aquifer system. About 20 percent of the active model area had an average potential recharge rate of less than 1 inch per year. Total precipitation, total recharge, and recharge as a percentage of precipitation increased from west to east. A substantial amount of the recharge water (39 percent) entering the glacial aquifer system travels through developed (urbanized) and agricultural landscapes, which are known to cause water-quality impairments. Regional climatic events, such as the 1988 to 1989 drought, are apparent in the potential recharge time series. Potential recharge generally increased across the glacial aquifer system between 2001 and 2011. A comparison of the potential recharge from the glacial SWB model to previous broad-scale recharge estimates reveals several important considerations for future SWB modeling applications. Shifts in the overall distribution of potential recharge between separate models can be explained by methods used to generate base-flow calibration target datasets. Spatial patterns in potential recharge simulated by SWB models are strongly dependent on the data and assumptions used to assign model cells to hydrologic soil groups. A review of several SWB models used to estimate groundwater recharge (and not surface runoff) revealed that model results are most sensitive to input climatic data, followed by surface runoff (curve number) and root-zone depth parameters.

Scientific Investigations Report↗
USGS2020

Assessment of soil and water resources in the Organ Mountains-Desert Peaks National Monument, New Mexico

The Organ Mountains-Desert Peaks National Monument (Monument) in southern New Mexico was established in 2014. Given anticipated future demands in the Monument for recreation, livestock grazing, and maintenance of rights-of-way (for example, pipelines and powerlines), the Bureau of Land Management (BLM) needs a better understanding of the current soil and water resources and how infrastructure improvements could affect these resources and the watershed. Specifically, the BLM is concerned with infiltration and erosion and their relations to existing or planned infrastructure, such as roads, campgrounds, location of livestock grazing, and rights-of-way. Alternatives to the current land-use conditions, land-management practices, and infrastructure will be assessed by BLM to best protect Monument resources. The U.S. Geological Survey, in cooperation with the BLM, conducted a study to assess the soil and water resources within the Monument to provide an inventory and compilation of natural-resource information needed by resource managers for the BLM’s land-use planning process for this new national monument. The overall objectives of this study were to (1) compile and interpret existing soil- and water-resource data for the Monument and (2) provide a basic assessment of the surface hydrological effects of selected alternatives to current land use and infrastructure. Data were compiled by using geographic information system software and evaluated for hydrologic and landscape properties that influence infiltration, runoff, and erosion. The effects of changing vegetation were simulated by using different scenarios in the Rangeland Hydrology and Erosion Model. Results of this model indicate areas where soil loss or runoff may occur.

New Mexico↗