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At least 1,441 records · Page 80Linked to original sources

USGS1982

Map showing geochemical analyses of panned stream sediments, Stansbury Roadless Areas, Tooele County, Utah

The Wilderness Act (Public Law 88-577, September 3, 1964) and related Acts require the U.S. Geological Survey and the U.S. Bureau of Mines to survey certain areas on Federal lands to determine their mineral resource potential. Results must be made available to the public and be submitted to the Administration and the Congress. This report presents the results of a geochemical survey of the Stansbury Roadless Areas, Tooele County, Utah. Part of this area was classified a Further Planning Area during the Second Roadless Area Review and Evaluation (RARE II) by the U.S. Forest Service, January 1979.

Utah↗

USGS1984

Geochemical maps of the Cornplanter Roadless Area, Warren County, Pennsylvania

The U.S. Geological Survey (USGS) made a reconnaissance geochemical survey of the Cornplanter Roadless Area (fig. 1) to test for indistinct or unexposed mineral deposits that might be recognized by their geochemical halos or patterns formed by the distribution of trace elements. Lesure, assisted by Andrew E. Grosz, collected 22 stream-sediment, 63 soil, and 23 rock samples from within and dear the study area during October 1980. All samples were analyzed for 31 elements using semi-quantitative spectrographic methods by Day in USGS laboratories, Denver, Colo. (table 1). In addition, the samples were also analyzed for zinc by means of an atomic absorption method by B.F. Arbogast and W.C. Martin, USGS laboratories, Denver Colo. J.T. Hanley and P.G. Schruben formatted the analytical data by computer methods for table 1.

Pennsylvania↗

USGS1987

Hydrologic and geochemical monitoring in Long Valley Caldera, Mono County, California, 1985

Hydrologic and geochemical monitoring, to detect changes caused by magmatic and tectonic processes in the Long Valley caldera has continued through 1985. The monitoring included the collection of the following types of data: chemical and isotopic composition of water and gases from springs, wells, and steam vents; temperatures in wells, springs, and steam vents; flow rates of springs and streams; water levels in wells; and barometric pressure and precipitation at several sites. In addition, reservoir temperatures for the geothermal system were estimated from computations based on chemical geothermometers applied to fluid samples from wells and springs. Estimates of thermal water discharged from springs were made on the basis of boron and chloride fluxes in surface waters for selected sites in the Casa Diablo area and along the Mammoth-Hot Creek drainage. These data are presented in tables and graphs. The Long Valley area was relatively quiescent throughout 1985 in terms of geodetic changes and seismic activity. As a consequence , the hydrologic system varied mainly in response to seasonal influences of temperature, atmospheric pressure, and precipitation. However, spring flows near Casa Diablo were influenced by pumping at the geothermal production well field nearby. (Author 's abstract)

Water-Resources Investigations Report↗

USGS2004

Physiological changes in largemouth bass exposed to paper mill effluents under laboratory and field conditions

We report here on studies designed to asses the effects of paper mill effluents on non-reproductive functions of free-ranging and captive Florida largemouth bass (Micropterus salmoides floridanus) This was accomplished by conducting an outdoor tank study, in which fish were exposed to well water or to 10%, 20%, 40%, and 80% full strength effluent for 28 or 56 days, and by sampling largemouth bass from sites within the St. Johns River, Florida, upstream and downstream from a paper mill plant. Blood and plasma samples from fish from the tank study and from fish sampled from the ambient sites were analyzed for over 20 variables. We also determined liver and spleen weights and examined them histologically. The most significant finding from the tank study was an increase in the concentration of albumin and hepatosomatic index for bass exposed to ???20% effluents for 56 days. Spleenosomatic index and number of melanomacrophage centers were decreased in bass from effluent-dominated sites (Palatka and Rice Creek), whereas concentrations of calcium, phosphorous, glucose, and creatinine were elevated in fish from these sites, compared to fish from reference streams. Fish from Rice Creek also had fewer red blood cells, and male bass from Palatka had lower concentrations of cholesterol. Plasma concentrations of albumin and hepatic concentrations of glutathione were elevated in males from Palatka, and both females and males from Rice Creek had higher concentrations of globulin. These results indicate a complex pattern of effects of paper mill effluents on several physiological functions. However, despite the myriad of treatment and site-related effects, most physiological parameters fell within normal ranges when compared to reports on largemouth bass and other freshwater species.

Ecotoxicology↗

USGS2009

Geophysical Investigation Along the Great Miami River From New Miami to Charles M. Bolton Well Field, Cincinnati, Ohio

Three geophysical profiling methods were tested to help characterize subsurface materials at selected transects along the Great Miami River, in southwestern Ohio. The profiling methods used were continuous seismic profiling (CSP), continuous resistivity profiling (CRP), and continuous electromagnetic profiling (CEP). Data were collected with global positioning systems to spatially locate the data along the river. The depth and flow conditions of the Great Miami River limited the amount and quality of data that could be collected with the CSP and CRP methods. Data from the CSP were generally poor because shallow reflections (less than 5 meters) were mostly obscured by strong multiple reflections and deep reflections (greater than 5 meters) were sparse. However, modeling of CRP data indicated broad changes in subbottom geology, primarily below about 3 to 5 meters. Details for shallow electrical conductivity (resistivity) (less than 3 meters) were limited because of the 5-meter electrode spacing used for the surveys. For future studies of this type, a cable with 3-meter electrode spacing (or perhaps even 1-meter spacing) might best be used in similar environments to determine shallow electrical properties of the stream-bottom materials. CEP data were collected along the entire reach of the Great Miami River. The CRP and CEP data did not correlate well, but the CRP electrode spacing probably limited the correlation. Middle-frequency (3,510 hertz) and high-frequency (15,030 hertz) CEP data were correlated to water depth. Low-frequency (750 hertz) CEP data indicate shallow (less than 5-meter) changes in electrical conductivity. Given the variability in depth and flow conditions on a river such as the Great Miami, the CEP method worked better than either the CSP or CRP methods.

Open-File Report↗

USGS1995

Hydrology of the Sevier-Sigurd ground-water basin and other ground-water basins, central Sevier Valley, Utah.

The hydrologic system in the central Sevier Valley, and more specifically the Sevier-Sigurd basin, is a complex system in which surface- and ground-water systems are interrelated. Seepage from an extensive irrigation system is the primary source of recharge to the basin-fill aquifer in the Sevier-Sigurd basin. Water-quality data indicate that inflow from streams and subsurface inflow that intersect evaporite deposits in the Arapien Shale does not adversely affect ground-water quality in the Sevier-Sigurd basin. Stable-isotope data indicate that large sulfate concentrations in water from wells are from the dissolution of gypsum within the basin fill rather than inflow from the Arapien Shale. A ground-water-flow model of the basin-fill aquifer in the Sevier-Sigurd basin was calibrated to steady-state conditions and transient conditions using yearly water-level changes from 1957-88 and monthly water-level changes from 1958-59. Predictive simulations were made to test the effects of reduced recharge from irrigation and increased well discharge. To simulate the effects of conversion from flood to sprinkler irrigation, recharge from irrigated fields was reduced by 50 percent. After twenty years, this reduction resulted in water-level declines of 1 to 8 feet in most of the basin, and a reduction in ground-water discharge to the Sevier River of 4,800 acre-ft/yr. Water-level declines of as much as 12 feet and a reduction in recharge to the Sevier River of 4,800 acre-ft/yr were the result of increasing well discharge near Richfield and Monroe by 25,000 acre-ft/yr.

Utah↗

USGS1981

Geologic map of the Beaver Creek Wilderness, McCreary County, Kentucky

The Beaver Creek Wilderness comprises approximately 4,800 acres and is principally within the cliffline bordering the Beaver Creek drainage basin in McCreary County, southeastern Kentucky. It is part of the Beaver Creek Cooperative Wildlife management Area in the Daniel Boone National Forest, which is managed by the U.S. Forest Service and the Kentucky Department of Fish and Wildlife Resources. The wilderness is about 11 mi southeast of Burnside, Ky., and is accessible from thr north and south via U.S. Route 27 and Forest Service Road 50, at its northwest border (fig. 1). From the east the area can be reached via State Route 90 and Forest Service Road 46, at the eastern end of the wilderness. The interiors is accessible by foot along an abandoned Forest Service road and by several primitive trails that extend along the major streams. The Beaver Creek Wilderness is centrally located at the western edge of the Appalachian coal regions and is within the highly dissected Cumberland Plateau section of the Appalachian Plateaus physiographic province (fig. 2). It is drained by Beaver Creek and tributaries, which flow northeastward into Cumberland Lake, a reservoir on the Cumberland River about 1 mi north of the wilderness. Altitudes range from about 730 ft on the lower part of Beaver Creek to about 1,200 ft at its headwaters.

Kentucky↗

USGS1987

Aeromagnetic map of the Hells Gate Roadless Area, Gila County, Arizona

The Hells Gate Roadless Area comprises about 31, 200 acres in the northern part of the Tonto National Forest. It lies beneath the Mogollon Rim between the communities of Payson and Young. The area is roughly a 4 by 15 mi strip along the deeply incised segment of Tonto Creek and along a 2 mi segment of Haigler Creek at its intersection with Tonto Creek. Elevations range from 2,960 ft in the lower Tonto Creek gorge near Gisela, in the southeastern part of the area, to 6,200 ft in the Green Valley Hills, in the northern part of the area. Local relief in the deep canyon of Tonto Creek is commonly greater than 1,000 ft. Hells Gate is the geographic name for the canyon at the confluence of Tonto Creek and Haigler Creek. Foot trails cross Tonto Creek at Hells Gate and between Houston Pocket and McDonald Pocket. Descent into Tonto Creek elsewhere is extremely difficult. The Hells Gate area lies in the central part of the Tonto Basin, which consists of Tonto Creek and tributaries draining the Mogollon escarpment and the northern Sierra Ancha. These streams dissect a table land which is the unconformable surface at the base of the Paleozoic section and the Mogollon Rim. This tableland is a part of the Colorado Plateau margin, which has been slightly structurally disrupted by late Cenozoic faulting and from which most of the Middle Proterozoic and Paleozoic strata have been stripped by subsequent erosion. Early Proterozoic rocks constitute about ninety percent of the exposed rocks in the roadless area and are composed of granite, granophyre, and intrusive and extrusive rhyolite (Conway, 1983).

Arizona↗

USGS2007

Formation of mixed Al-Fe colloidal sorbent and dissolved-colloidal partitioning of Cu and Zn in the Cement Creek - Animas River Confluence, Silverton, Colorado

Transport and chemical transformations of dissolved and colloidal Al, Fe, Cu and Zn were studied by detailed sampling in the mixing zone downstream from the confluence of Cement Creek (pH 4.1) with the Animas River (pH 7.6). Complete mixing resulted in circumneutral pH in the downstream reach of the 1300 m study area. All four metals were transported through this mixing zone without significant losses to the streambed, and they exhibited transformations from dissolved to colloidal forms to varying degrees during the mixing process. Nearly all of the Al formed colloidal hydrous Al oxides (HAO) as pH increased (4.8–6.5), whereas colloidal hydrous Fe oxides (HFO) were supplied by Cement Creek as well as formed in the mixing zone primarily at higher pH (>6.5). The short travel time through the mixing zone (approx. 40 min) and pH limited the formation of HFO from dissolved Fe 2+ supplied by Cement Creek. Although the proportions of HAO and HFO varied as the streams mixed, the colloidal sorbent typically was enriched in HAO relative to HFO by a factor of 1.5–2.1 (by mole) in the pH range where dissolved-to-colloidal partitioning of Cu and Zn was observed. Model simulations of sorption by HFO (alone) greatly underestimated the dissolved-to-colloidal partitioning of Zn. Previous studies have shown that HAO–HFO mixtures can sorb greater amounts of Zn than HFO alone, but the high Zn-to-sorbent ratio in this mixing zone could also account for greater partitioning. In contrast to Zn, comparisons with model simulations did not show that Cu sorption was greater than that for HFO alone, and also indicated that sorption was possibly less than what would be expected for a non-interactive mixture of these two sorbents. These field results for Cu, however, might be influenced by (organic) complexation or other factors in this natural system. Laboratory mixing experiments using natural source waters (upstream of the confluence) showed that the presence of HFO in the mixed sorbent resulted in greater Cu partitioning than for HAO alone, and that the effect was greater with increasing (mole fraction) HFO. This was consistent with field results that showed greater Cu sorption when additional HFO was formed in the downstream reach of the mixing zone. Further research is needed to identify the significance of surface-related mechanisms specific to HAO–HFO mixtures that could affect the partitioning of Cu in natural systems.

Colorado↗

USGS2025

Dynamic rating method for computing discharge and stage from time-series data

Ratings are used for several reasons in water-resources investigations. The simplest rating relates discharge to the stage of a river (the stage-discharge relation). From a pure hydrodynamics perspective, all rivers and streams have some form of hysteresis in the relation between stage and discharge because flow becomes unsteady as a flood wave passes. The stage-discharge relation is unable to represent hysteresis. However, a dynamic rating method can capture hysteresis, which is driven by the variable energy slope of a flood wave. A dynamic rating method called DYNPOUND, which accommodates compact and compound channel geometry, was developed by simplifying the one-dimensional Saint-Venant equations. The DYNPOUND method was developed in the Python programming language and computes discharge from stage and stage from discharge. Stage and discharge time series computed with this dynamic rating method were compared to the U.S. Geological Survey (USGS) published stage and discharge time series. The results from the DYNPOUND method were also compared to in-person field measurements of stage and discharge made at 10 USGS streamgages. DYNPOUND was calibrated for 10 USGS streamgages using published discharge time-series data computed with a simple rating method. The calibration objective was to minimize the mean squared logarithmic error (MSLE) of the DYNPOUND-computed discharge with respect to the discharge time series computed by a simple rating method. For each site, the calibration process also included comparing all field measurements within a selected water year to the corresponding DYNPOUND-computed discharge data points. The MSLE of the DYNPOUND-computed discharge time series for the 10 sites ranged from 8.51×10 −4 to 1.36×10 −1 . For each site, an event-based period was selected to compare the discharge time series computed with the dynamic rating method to discharge field measurements made at the streamgages; the range of MSLE for the 10 DYNPOUND-computed discharge sites was from 4.79×10 −4 to 2.30×10 −2 .

continental United States↗

USGS2018

The distribution and role of functional abundance in cross‐scale resilience

The cross‐scale resilience model suggests that system‐level ecological resilience emerges from the distribution of species’ functions within and across the spatial and temporal scales of a system. It has provided a quantitative method for calculating the resilience of a given system and so has been a valuable contribution to a largely qualitative field. As it is currently laid out, the model accounts for the spatial and temporal scales at which environmental resources and species are present and the functional roles species play but does not inform us about how much resource is present or how much function is provided. In short, it does not account for abundance in the distribution of species and their functional roles within and across the scales of a system. We detail the ways in which we would expect species’ abundance to be relevant to the cross‐scale resilience model based on the extensive abundance literature in ecology. We also put forward a series of testable hypotheses that would improve our ability to anticipate and quantify how resilience is generated, and how ecosystems will (or will not) buffer recent rapid global changes. This stream of research may provide an improved foundation for the quantitative evaluation of ecological resilience.

Ecology↗

USGS1947

Geologic features of dam sites in the Nehalem, Rogue, and Willamette River basins, Oregon, 1935-37

The present report comprises brief descriptions of geologic features at 19 potential dam sites in the Nehalem, Rogue, and Willamette River basins in western Oregon. The topography of these site and of the corresponding reservoir site was mapped in 1934-36 under an allocation of funds, by the Public Works Administration for river-utilization surveys by the Conservation Branch of the United States Geological Survey. The field program in Oregon has been under the immediate charge of R. O. Helland. The 19 dam sites are distributed as follows: three on the Nehalem River, on the west or Pacific slope of the Oregon Coast range; four on Little Butte Creek and two on Evans Creek, tributaries of the Rogue River in the eastern part of the Klamath Mountains; four on the South and Middle Santiam Rivers, tributaries of the Willamette River from the west slope of the Cascade mountains; and six on tributaries of the Willamette River from the east slope of the Coast Range. Except in the Evans Creek basin, all the rocks in the districts that were studied are of comparatively late geological age. They include volcanic rocks, crystalline rocks of several types, marine and nonmarine sedimentary rocks, and recent stream deposits. The study of geologic features has sought to estimate the bearing power and water-tightness of the rocks at each dam site, also to place rather broad limits on the type of dam for which the respective sites seem best suited. It was not considered necessary to study the corresponding reservoir sites in detail for excessive leakage appears to be unlikely. Except at three of the four site in the Santiam River basin, no test pits have been dug nor exploratory holes drilled, so that geologic features have been interpreted wholly from natural outcrops and from highway and railroad cuts. Because these outcrops and cuts are few, many problems related to the construction and maintenance of dams can not be answered at the this time and all critical features of the sites should be thoroughly explored by test pits and drilled holes before any dam is designed. This applied especially to sites in the Nehalem and Willamette River basins where commonly the cover of timber and brush is dense and the rocks are rather deeply weathered. On the Middle Santiam and South Santiam Rivers, the Cascadia, Greenpeter, and Sweet Home sits have been studies intensively by the United States Engineer Department, whose work included exploration by diamond-drill holes and test pits. Their conclusions as to geologic features are given in a report by McKitrick and have been reviewed by the writer. Data from this source have been used freely in the discussion of the respective sites in this report. The probability of destructive earthquakes in the region appears to be small but is not negligible. Prudence suggests that any high dam should embody features to assure stability against moderately strong earth motions.

Oregon↗

USGS1983

Potential effects of surface coal mining on the hydrology of the Snider Creek area, Rosebud and Ashland coal fields, southeastern Montana

The Snider Creek area of the Rosebud and Ashland coal fields contains strippable reserves of Federal coal that have been identified for potential lease sale. A hydrologic study has been conducted in the potential lease area to describe the existing hydrologic systems and to assess potential impacts of surface coal mining on local water resources. Hydrogeologic data collected from stock wells, observation wells, and drill holes indicate that shallow aquifers exist within the Tullock, Lebo Shale, and tongue River Members of the Fort Union Formation (Paleocene age) and within valley alluvium (Pleistocene and Holocene age). Most of the wells in the area are completed in the basal part of the Tongue River Member or in the upper part of the Lebo Shale Member and are used for watering of livestock. Small stock reservoirs are the primary source of surface water; Snider Creek and all other streams that originate in the area are ephemeral. The Terrett coal bed, the primary coal bed of the area, is located above the water table. Mining of the Terrett coal bed would destroy one stock well and several small reservoirs. Four other wells near the coal outcrop might be destroyed by mining. Alternative ground-water supplies are available to replace those lost by mining. Degradation of the quality of ground water, caused by the leaching of soluble salts from mine spoils, is not anticipated. (USGS)

Montana↗

USGS1949

Ground water in the Cul-de-Sac Plain, Haiti

The Cul-de-Sac Plain is perhaps the most important agricultural area in Haiti because of its nearness and accessibility to Port-au-Prince, the nation's capital, metropolis, and principal seaport. Most of the agricultural produce consumed in Port-au-Prince as well as a considerable part of that exported from Haiti is grown in the plain. Because of variable and poorly distributed rainfall, high temperature, and high evaporation, semiarid climatic conditions prevail in the plain. Irrigation is, therefore, necessary for successful farming. There are no regulatory or storage facilities on the streams that enter the plain, but the mean and low-water stream flow and the discharge of springs are almost entirely appropriated for irrigation. Ground water has been utilized for irrigation to an increasing extent by the Haitian American Sugar Company, which has put down about 100 wells in the plain since 1919. Outside the existing irrigated areas of the plain are large tracts of potentially irrigable land that are uncultivated and agriculturally unproductive for lack of water. The object of the present study was to determine the possibilities of bringing these lands into cultivation by irrigation from wells. This study was part of a larger program of the Food Supply Division, Institute of Inter-American Affairs, to increase the production of food in Haiti. From September through November 1948 the senior author, a member of the U. S. Geological Survey, spent three months in the field in an investigation of the geology and ground-water resources of the Cul-de-Sac Plain. He was ably assisted by Mr. Rémy C. Lemoine, Haitian engineer-geologist, employed by the Food Supply Division. The field work included principally the geologic mapping of' the plain and the adjacent mountain borders, a ground-water inventory of existing wells and springs, and a general evaluation of significant geologic and hydrologic features.

Cul-de-sac Plain↗

USGS2019

Comparison of continuous and interrupted lampricide block toxicity to sea lamprey and lake sturgeon

Lake Sturgeon ( Acipenser fulvescens , LST) is a state, provincial, and tribal species of special concern that is sensitive to lampricides used in sea lamprey control. As such, there is significant interest in the Great Lakes fisheries community to develop alternative sea lamprey ( Petromyzon marinus , SL) control approaches to minimize impacts on LST for applicable LST producing streams. Currently, lampricides are applied continuously to streams for 10 to 14 hours to achieve at least a 9-hour lampricide block at or above the SL minimum lethal concentration (MLC). Once the application of lampricides are initiated it usually takes 1-4 hours for the lampricide concentration to build to the target concentration during treatments depending on the flow dynamics of the stream. An interrupted lampricide block, wherein the treatment consists of two lampricide blocks (cumulative MLC of at least 9 hours) with a break in the middle, has been shown to decrease burrowing mayfly ( Hexagenia limbata ) mortality and resulted in no change to MLC when interruptions were up to 12 hours in duration. This study compared mortality of LST and SL during continuous and interrupted lampricide blocks with the goal of establishing whether an interrupted lampricide block treatment could be used to protect LST while maintaining treatment efficacy. Results show that there was no difference in toxicity to larval SL or LST between the interrupted block and continuous exposures. No differences were detected among calculated LC25s andLC50s for LST in the interrupted block tests compared to the continuous block tests during laboratory and streamside bioassays. An interrupted block field trial on Eliza Creek resulted in high mortality among caged larval SL (99.5%); however, posttreatment surveys estimated the treatment kill at 83.5% compared to >99% from the two previous continuous block treatments (2007, 2001). This suggests a substantial decrease in treatment effectiveness when using the interrupted block strategy. The lack of separation in toxicity between LST and SL under continuous interrupted block treatment and the reduced efficacy of the interrupted treatment block combine to make this treatment method a less desirable option.

Report↗

USGS2021

Depths inferred from velocities estimated by remote sensing: A flow resistance equation-based approach to mapping multiple river attributes at the reach scale

Remote sensing of flow conditions in stream channels could facilitate hydrologic data collection, particularly in large, inaccessible rivers. Previous research has demonstrated the potential to estimate flow velocities in sediment-laden rivers via particle image velocimetry (PIV). In this study, we introduce a new framework for also obtaining bathymetric information: Depths Inferred from Velocities Estimated by Remote Sensing (DIVERS). This approach is based on a flow resistance equation and involves several assumptions: steady, uniform, one-dimensional flow and a direct proportionality between the velocity estimated at a given location and the local water depth, with no lateral transfer of mass or momentum. As an initial case study, we performed PIV and inferred depths from videos acquired from a helicopter hovering at multiple waypoints along a large river in central Alaska. The accuracy of PIV-derived velocities was assessed via comparison to field measurements and the performance of an optimization-based approach to DIVERS specification of roughness

Alaska↗

USGS2000

Geohydrology and numerical simulation of groundwater flow in the central Virgin River Basin of Iron and Washington Counties, Utah

Because rapid growth of communities in Washington and Iron Counties, Utah, is expected to cause an increase in the future demand for water resources, a hydrologic investigation was done to better understand ground-water resources within the central Virgin River basin. This study focused on two of the principal ground-water reservoirs within the basin: the upper Ash Creek basin ground-water system and the Navajo and Kayenta aquifer system. The ground-water system of the upper Ash Creek drainage basin consists of three aquifers: the uppermost Quaternary basin-fill aquifer, the Tertiary alluvial-fan aquifer, and the Tertiary Pine Valley monzonite aquifer. These aquifers are naturally bounded by the Hurricane Fault and by drainage divides. On the basis of measurements, estimates, and numerical simulations of reasonable values for all inflow and outflow components, total water moving through the upper Ash Creek drainage basin ground-water system is estimated to be about 14,000 acre-feet per year. Recharge to the upper Ash Creek drainage basin ground-water system is mostly from infiltration of precipitation and seepage from ephemeral and perennial streams. The primary source of discharge is assumed to be evapotranspiration; however, subsurface discharge near Ash Creek Reservoir also may be important. The character of two of the hydrologic boundaries of the upper Ash Creek drainage basin ground-water system is speculative. The eastern boundary provided by the Hurricane Fault is assumed to be a no-flow boundary, and a substantial part of the ground-water discharge from the system is assumed to be subsurface outflow beneath Ash Creek Reservoir along the southern boundary. However, these assumptions might be incorrect because alternative numerical simulations that used different boundary conditions also proved to be feasible. The hydrogeologic character of the aquifers is uncertain because of limited data. Differences in well yield indicate that there is considerable variability in the transmissivity of the basin-fill aquifer. Field data also indicate that the basin-fill aquifer is more transmissive than the underlying alluvial-fan aquifer. Data from the Pine Valley monzonite aquifer indicate that its transmissivity may be highly variable and that it is strongly influenced by the connection of fractures. The Navajo and Kayenta aquifers provide most of the potable water to the municipalities of Washington County. Because of large outcrop exposures, uniform grain size, and large stratigraphic thickness, these formations are able to receive and store large amounts of water. In addition, structural forces have resulted in extensive fracture zones that enhance ground-water recharge and movement within these aquifers. Aquifer testing of the Navajo aquifer indicates that horizontal hydraulic-conductivity values range from 0.2 to 32 feet per day at different locations and may be primarily dependent on the extent of fracturing. Limited data indicate that the Kayenta aquifer generally is less transmissive than the Navajo aquifer. The aquifers are bounded to the south and west by the erosional extent of the formations and to the east by the Hurricane Fault, which completely offsets these formations and is assumed to be a lateral no-flow boundary. Like the Hurricane Fault, the Gunlock Fault is assumed to be a lateral no-flow boundary that divides the Navajo and Kayenta aquifers within the study area into two parts: the main part, between the Hurricane and Gunlock Faults; and the Gunlock part, west of the Gunlock Fault. Generally, the water in the Navajo and Kayenta aquifers contains few dissolved minerals. However, two distinct areas contain water with dissolved-solids concentrations greater than 500 milligrams per liter: a larger area north of the city of St. George and a smaller area a few miles west of the town of Hurricane. Mass-balance calculations indicate that in the higher-dissolved-solids area north of St. George, as much as 2.7 cubic feet per second may be entering the aquifer from underlying formations. For the area west of Hurricane, as much as 1.5 cubic feet per second may be entering the aquifer from underlying formations. On the basis of measurements, estimates, and numerical simulations, total water moving through the Navajo and Kayenta aquifers is estimated to be about 25,000 acre-feet per year for the main part and 5,000 acre-feet per year for the Gunlock part. The primary source of recharge is assumed to be infiltration of precipitation in the main part and seepage from the Santa Clara River in the Gunlock part. The primary source of discharge is assumed to be well discharge for both the main and Gunlock parts of the aquifers. Numerical simulations indicate that faults with major offset, such as the Washington Hollow Fault and an unnamed fault near Anderson Junction, may impede horizontal ground-water flow. Also, increased horizontal hydraulic conductivity along the orientation of predominant surface fracturing may be an important factor in regional ground-water flow. Simulations with increased north-south hydraulic conductivity substantially improved the match to measured water levels in the central area of the model between Snow Canyon and Mill Creek. Numerical simulation of the Gunlock part, using aquifer properties determined for the city of St. George municipal well field, resulted in a reasonable representation of regional water levels and estimated seepage from and to the Santa Clara River. To further quantify the Gunlock part of the Navajo and Kayenta aquifers, a better understanding of ground-water flow at the Gunlock Fault is needed.

Utah↗

USGS2000

Simple Techniques For Assessing Impacts Of Oil And Gas Operations On Federal Lands - A Field Evaluation At Big South Fork National River And Recreation Area, Scott County, Tennessee

Simple, cost-effective techniques are needed for land managers to assess the environmental impacts of oil and gas production activities on public lands so that sites may be prioritized for further, more formal assessment or remediation. These techniques should allow the field investigator to extend the assessment beyond the surface disturbances documented by simple observation and mapping using field-portable instruments and expendable materials that provide real-time data. The principal contaminants of current concern are hydrocarbons, produced water, and naturally occurring radioactive materials (NORM). Field investigators can examine sites for the impacts of hydrocarbon releases using a photoionization detector (PID) and a soil auger. Volatile organic carbon (VOC) in soil gases in an open auger hole or in the head space of a bagged and gently warmed auger soil sample can be measured by the PID. This allows detection of hydrocarbon movement in the shallow subsurface away from areas of obvious oil-stained soils or oil in pits at a production site. Similarly, a field conductivity meter and chloride titration strips can be used to measure salts in water and soil samples at distances well beyond areas of surface salt scarring. Use of a soil auger allows detection of saline subsoils in areas where salts may be flushed from the surface soil layers. Finally, a microRmeter detects the presence of naturally occurring radioactive materials (NORM) in equipment and soils. NORM often goes undetected at many sites although regulations limiting NORM in equipment and soils are being promulgated in several States and are being considered by the USEPA. With each technique, background sampling should be done for comparison with impacted areas. The authors examined sites in the Big South Fork National River and Recreation Area in November of 1999. A pit at one site at the edge of the flood plain of a small stream had received crude oil releases from a nearby tank. Auger holes down gradient from the pit showed the presence of anomalous concentrations of VOCs at depths of 3 feet for a distance of about 50 feet. PID readings at other sites showed 1) one reclaimed site where hydrocarbon biodegradation was incomplete; 2) one reclaimed site where biodegradation had left no traces of VOCS; and 3) two sites where traces of substantial offsite migration of hydrocarbons occurred. Produced water salts at one site have migrated many 100s of feet downvalley from the area of salt scarring and tree death adjacent to the pits. Naturally occurring radioactivity (NORM) at most sites was at background. One site showed anomalous radioactivity related to NORM in a small brine pit. Some of this NORM has moved downslope from the outlet pipe to the pit.

Open-File Report↗