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At least 235 records · Page 13Linked to original sources
USGS2001

Hydrologic budgets for the Madison and Minnelusa aquifers, Black Hills of South Dakota and Wyoming, water years 1987-96

The Madison and Minnelusa aquifers are two of the most important aquifers in the Black Hills area of South Dakota and Wyoming. Quantification and evaluation of various hydrologic budget components are important for managing and understanding these aquifers. Hydrologic budgets are developed for two scenarios, including an overall budget for the entire study area and more detailed budgets for subareas. Budgets generally are combined for the Madison and Minnelusa aquifers because most budget components cannot be quantified individually for the aquifers. An average hydrologic budget for the entire study area is computed for water years 1987-96, for which change in storage is approximately equal to zero. Annual estimates of budget components are included in detailed budgets for nine subareas, which consider periods of decreasing storage (1987-92) and increasing storage (1993-96). Inflow components include recharge, leakage from adjacent aquifers, and ground-water inflows across the study area boundary. Outflows include springflow (headwater and artesian), well withdrawals, leakage to adjacent aquifers, and ground-water outflow across the study area boundary. Leakage, ground-water inflows, and ground-water outflows are difficult to quantify and cannot be distinguished from one another. Thus, net ground-water flow, which includes these components, is calculated as a residual, using estimates for the other budget components. For the overall budget for water years 1987-96, net ground-water outflow from the study area is computed as 100 ft 3 /s (cubic feet per second). Estimates of average combined budget components for the Madison and Minnelusa aquifers are: 395 ft 3 /s for recharge, 78 ft 3 /s for headwater springflow, 189 ft 3 /s for artesian springflow, and 28 ft 3 /s for well withdrawals. Hydrologic budgets also are quantified for nine subareas for periods of decreasing storage (1987-92) and increasing storage (1993-96), with changes in storage assumed equal but opposite. Common subareas are identified for the Madison and Minnelusa aquifers, and previous components from the overall budget generally are distributed over the subareas. Estimates of net ground-water flow for the two aquifers are computed, with net ground-water outflow exceeding inflow for most subareas. Outflows range from 5.9 ft 3 /s in the area east of Rapid City to 48.6 ft 3 /s along the southwestern flanks of the Black Hills. Net groundwater inflow exceeds outflow for two subareas where the discharge of large artesian springs exceeds estimated recharge within the subareas. More detailed subarea budgets also are developed, which include estimates of flow components for the individual aquifers at specific flow zones. The net outflows and inflows from the preliminary subarea budgets are used to estimate transmissivity of flow across specific flow zones based on Darcy’s Law. For estimation purposes, it is assumed that transmissivities of the Madison and Minnelusa aquifers are equal in any particular flow zone. The resulting transmissivity estimates range from 90 ft 2 /d to about 7,400 ft 2 /d, which is similar to values reported by previous investigators. The highest transmissivity estimates are for areas in the northern and southwestern parts of the study area, and the lowest transmissivity estimates are along the eastern study area boundary. Evaluation of subarea budgets provides confidence in budget components developed for the overall budget, especially regarding precipitation recharge, which is particularly difficult to estimate. Recharge estimates are consistently compatible with other budget components, including artesian springflow, which is a dominant component in many subareas. Calculated storage changes for subareas also are consistent with other budget components, specifically artesian springflow and net ground-water flow, and also are consistent with water-level fluctuations for observation wells. Ground-water budgets and flowpaths are especially complex in the southern Black Hills area; however, budget results are consistent with geochemical interpretations by previous investigators.

South Dakota, Wyoming↗
USGS1994

Ground-water discharge from the Coastal Plain of Virginia

The Chesapeake Bay and other important surface- water bodies receive ground water that discharges directly from the Coastal Plain of Virginia. This report presents estimates of the average annual ground-water discharge from the Coastal Plain of Virginia using two approaches. Average annual ground-water discharge from 16 gaged watersheds in the Coastal Plain of Virginia estimated by use of a streamflow hydrograph-separation approach ranged from 7.5 to 12.5 inches per year; the median was 10.8 inches per year. These estimates are similar to those reported by other investigators for the Coastal Plain in the nearby Delmarva Peninsula. Average annual ground-water discharge also was estimated by use of a hydrogeologic-area approach. In this approach, areas that have similar hydrogeologic charac- teristics are grouped and multiple regression is used to determine the relation between the hydro- geologic areas and ground-water discharge. The multiple-regression analysis indicates that ground-water discharge within the Coastal Plain of Virginia is a function of the relative areal extent of well-drained uplands and moderately well-drained uplands. On the basis of the hydro- geologic-area approach, ground-water discharge from the Coastal Plain of Virginia averages 9.9 inches per year.

Water-Resources Investigations Report↗
USGS1995

Ground-water flow and water quality in the sand aquifer of Long Beach Peninsula, Washington

This report describes an investigation of ground-water flow and water quality in the sand aquifer of the Long Beach Peninsula. The peninsula is located in the southwestern corner of the State of Washington, is about 27 miles long, and has an average width of about 1.5 miles. It is surrounded by seawater, by the Pacific Ocean on the west and Willapa Bay on the east. Water supplies on the peninsula are derived mostly from a local water-table aquifer composed largely of sand. The recent growth of population on the peninsula and the projected future growth have created concerns about the quantity and quality of the ground-water resource. Some issues include declining ground-water levels from increased pumpage, and ground-water contamination from seawater intrusion, pesticides or fertilizers from cranberrygrowing areas, and septic-system effluent. The ground-water system of the Long Beach Peninsula consists of a sand aquifer with some lenses of silt and clay that may act as confining beds in local areas. Data are lacking or inconsistent to define a confining bed that extends throughout the peninsula. Hydraulic conductivity calculated from slug tests in 58 shallow wells ranged from 10 to 37 feet per day with a median of 22 feet per day. Average annual ground-water recharge by infiltration and percolation of precipitation is estimated to be about 58 inches or 111,000 acre-feet, which is 72 percent of the average annual precipitation of 80 inches. Average annual ground-water discharge is estimated to be about 30,200 acre-feet to the Pacific Ocean, 56,000 acre-feet to Willapa Bay, and 24,800 acre-feet to surface-water drainage channels. Ground-water movement is generally perpendicular to the spine of the peninsula. A ground-water divide occurs along a north-south line and ground water flows west or east from the divide toward the Pacific Ocean or Willapa Bay. There does not appear to have been any long-term decline of the water table of the sand aquifer from 1974-92. Ground-water levels measured at three east-west cross sections in 1974-75 were at about the same altitude as water levels measured in 1992. Relatively accurate individual regression relations were developed at 45 wells with ground-water altitude as a response variable and cumulative precipitation for 4 months as an explanatory variable. The average coefficient of determination for all individual relations was 0.77, with a range of 0.11 to 0.89. Some empirical frequency or probability relations for precipitation and ground-water levels were used to estimate how often the maximum water levels measured in this study would be expected to occur in the future. These water levels reflected the lower-than-average precipitation that occurred during the study. Assuming that the annual maximum precipitation for 4 consecutive months is random and independent, the historical record of precipitation is representative of the future distribution of precipitation, and the relation between precipitation and water levels is accurate and stationary; a probability analysis of the historical record indicates that in any one year in the future there is a probability of 70 percent that the maximum water levels measured in wells during the winter of 1991-92 would be equaled or exceeded. The shallow ground water had generally low dissolved-solids concentrations in July 1992, with a median concentration of 92 milligrams per liter (mg/L) and a range of 56 to 218 mg/L. Sodium was the dominant cation and bicarbonate was the dominant anion. The distribution of hardness of the water samples was 84 percent with soft water and 16 percent with moderately hard water. The water quality of the shallow ground water was generally good, with a few small to moderate problems. A natural problem is locally high concentrations of dissolved iron. About 30 percent of the water samples had dissolved-iron concentrations of greater than 0.3 mg/L, which is the secondary maximum contaminant level established by the U.S. Environmental Protection Agency. No appreciable amount of seawater has intruded into the sand aquifer. The samples of shallow ground water collected in July 1992 had a median chloride concentration of 15 mg/L and a maximum concentration of 52 mg/L. The heavy average annual precipitation of about 80 inches, large average annual ground-water recharge of about 58 inches or 111,000 acre-feet, and small ground-water withdrawal rate (about 780 acre-feet per year in 1992) combine to maintain a thick freshwater lens of ground water that prevents seawater intrusion throughout the year. Agricultural activities do not appear to have appreciably affected the quality of shallow ground water on the Long Beach Peninsula. The concentration of nitrate in ground water was not significantly higher near cranberry-growing areas, and no sample of ground water or surface water had concentrations of selected pesticides or associated compounds that were above the analytical detection limits. Of the seven ground-water samples in which bacteria were detected, only one sample appeared to be related to agriculture; that sample was from a well located in an area where cattle graze for part of the year. Septic systems probably caused an increase in the concentration of nitrate in shallow ground water in areas of higher population density. Concentrations of nitrate were significantly related to population density. However, the concentrations were not generally high; median concentrations of nitrate increased from less than 0.05 mg/L in areas of low population density to 0.74 mg/L in areas of high density. Septic systems did not cause regional bacterial contamination of the ground water. Bacteria were detected in seven ground-water samples; however, only two of those samples were from wells that are close to septic systems. A limited amount of historical water-quality data is available for the peninsula; therefore, it is difficult to assess long-term changes. From 1968-92, chloride concentrations and values of specific conductance appear to have remained stable. Likewise, it appears that nitrate concentrations did not change from 1987-92.

Washington↗
USGS2019

Snake River fall chinook salmon life history investigations, 2018 annual report

The following report is divided into three sections each of which describes work conducted by different project cooperators. Chapter One describes smallmouth bass (Micropterus dolomieu) predation on subyearling fall Chinook salmon (Oncorhynchus tshawytscha) in Lower Granite Reservoir in 2018. Smallmouth bass abundance increased seasonally in shoreline habitats and was highest in the lower reach of the reservoir (1,239 fish/km of shoreline). Abundance ranged from 40,743 to 81,595 in 2018. We examined the relationship between smallmouth bass predation and subyearling habitat suitability. Bass abundance was highest in “natural” habitat (i.e., habitat with natural substrate that was not deemed suitable for subyearlings) and fish were generally larger in habitat classified as “suitable” (i.e., habitat deemed suitable rearing) for subyearling Chinook salmon. Subyearlings were present in all habitat types sampled but their abundance was 2–3 times lower in the lower reach of the reservoir. Sand rollers (Percopsis transmontana)—a common prey of smallmouth bass—were present in greatest numbers in “suitable” habitat in the upper reach and “natural” habitat in the middle reservoir reach, but few were observed in the lower reservoir. The total loss of subyearlings to smallmouth bass predation in 2018 (120,023) was slightly less than one-half that of 2016 (266,988) and more than twice that of 2017 (47,830). Total sand roller loss in 2018 (149,106) was slightly more than one-half the losses estimated in 2016 and 2017. Chapter Two describes the feasibility of using stable isotopes of carbon and nitrogen to distinguish hatchery and natural origin subyearling fall Chinook salmon that were consumed by smallmouth bass. A discriminant function was fit from isotopic signatures and fork length from known-origin hatchery and natural subyearlings. The function had an overall correct classification rate of 97.2%. Of subyearlings consumed by smallmouth bass the function correctly classified 94.3% of hatchery fish but only 64.3% of natural fish based on fish origins that were validated with parentage-based tagging (PBT) analysis. Most of the fish consumed by smallmouth bass were of hatchery origin and most of those were of the spring/summer run early in the year and of the fall run later in the year. Based on analysis of known-origin hatchery fish collected at Lower Granite Dam through time following release, using stable isotopes as a discriminatory tool is probably only effective for about two weeks following release, but may have greater utility in unimpounded systems where fish emigrate seaward more quickly. The third section of this report is a Master’s Thesis that covers work conducted under contracts 46273 REL 14 and 79562. The first chapter of the thesis examined growth of subyearling fall Chinook salmon rearing in three sections of the Snake and Clearwater rivers and Lower Granite Reservoir. Growth and food consumption were highest in the reservoir section than in riverine sections, though growth was not significantly higher in the reservoir for the full duration of the study. Julian date was the strongest predictor of growth and consumption, and both growth and consumption decreased over the course of the study, even when accounting for allometric growth effects. Findings suggest that fish rearing in the reservoir section during their early growth period may have an ephemeral energetic advantage relative to fish rearing in natal river sections. The second chapter of the thesis examined the spatial variation in natal river rearing and downstream movement in Snake River fall Chinook salmon. Based on otolith analyses, natal origin was related to differential habitat use with fish from the Clearwater River accruing 48% of their freshwater growth in their natal river compared to 40% for Snake River fish. These differences were associated with different mean size at natal river exit and at ocean entry.

Idaho, Washington, Oregon↗
USGS2021

Yellowstone grizzly bear investigations 2020 - Annual report of the Interagency Grizzly Bear Study Team

This Annual Report summarizes results of grizzly bear ( Ursus arctos ) research and monitoring conducted in the Greater Yellowstone Ecosystem (GYE) by the Interagency Grizzly Bear Study Team (IGBST) during 2020. The research and monitoring program is focused on population estimation and demographics, food monitoring, and habitat monitoring. This report also presents a summary of grizzly bear management actions to address conflict situations and agency outreach efforts. The information presented in this report is a summary of annual data collections. Data, analyses, and summaries presented here supersede those published previously and may be subject to change contingent on additional information, future publications, and the peer-review process.

Idaho, Montana, Wyoming↗
USGS2015

The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977.

Alaska↗
USGS2004

Reductive dechlorination of chlorinated ethenes under oxidation-reduction conditions and potentiometric surfaces in two trichloroethene-contaminated zones at the Double Eagle and Fourth Street Superfund sites in Oklahoma City, Oklahoma

The Double Eagle Refining Superfund site and the Fourth Street Abandoned Refinery Superfund site are in northeast Oklahoma City, Oklahoma, adjacent to one another. The Double Eagle facility became a Superfund site on the basis of contamination from lead and volatile organic compounds; the Fourth Street facility on the basis of volatile organic compounds, pesticides, and acid-base neutral compounds. The study documented in this report was done to investigate whether reductive dechlorination of chlorinated ethenes under oxidation-reduction conditions is occurring in two zones of the Garber-Wellington aquifer (shallow zone 30–60 to 75 feet below land surface, deep zone 75 to 160 feet below land surface) at the sites; and to construct potentiometric surfaces of the two water-yielding zones to determine the directions of groundwater flow at the sites. The presence in some wells of intermediate products of reductive dechlorination, dichloroethene and vinyl chloride, is an indication that reductive dechlorination of trichloroethene is occurring. Dissolved oxygen concentrations (less than 0.5 milligram per liter) indicate that consumption of dissolved oxygen likely had occurred in the oxygen-reducing microbial process associated with reductive dechlorination. Concentrations of nitrate and nitrite nitrogen (generally less than 2.0 and 0.06 milligrams per liter, respectively) indicate that nitrate reduction probably is not a key process in either aquifer zone. Concentrations of ferrous iron greater than 1.00 milligram per liter in the majority of wells sampled indicate that iron reduction is probable. Concentrations of sulfide less than 0.05 milligram per liter in all wells indicate that sulfate reduction probably is not a key process in either zone. The presence of methane in ground water is an indication of strongly reducing conditions that facilitate reductive dechlorination. Methane was detected in all but one well. In the shallow zone in the eastern part of the study area, ground water flowing from the northwest and south coalesces in a potentiometric trough, then moves westward and ultimately northwestward. In the western part of the study area, ground water in the shallow zone flows northwest. In the deep zone in the eastern part of the study area, ground water generally flows northwestward; and in the western part of the study area, ground water in the deep zone generally flows northward.

Oklahoma↗
USGS1996

Compilation and preliminary interpretations of hydrologic and water-quality data from the Railroad Industrial Area, Fairbanks, Alaska, 1993-94

Commercial and industrial activities in the Railroad Industrial Area in Fairbanks, Alaska, have resulted in accidental releases of chemicals to the subsurface. Such releases have generated concern regarding local ground-water quality and the potential impact on nearby water-supply wells. Consequently, a study is being conducted to characterize the environmental and hydrologic conditions in the area. Existing reports from numerous previous investigations in the area were reviewed and relevant information from these documents was compiled. Both ground- and surface-water elevations were measured approximately monthly at as many as 50 sites during mass measurements. Selected sites were measured more frequently to assess short-term changes in the ground- and surface-water systems. Supplemental data were also collected outside of the study area to aid in interpretation. Ground water was sampled and analyzed to define the extent of the area affected by petroleum hydrocarbons and chlorinated solvents. Data show that water levels in nearby rivers and sloughs have a considerable influence on ground-water flow in the study area. Seasonal and shorter term changes in river stage frequently alter and even reverse the direction of ground-water flow. The local ground-water system typically has an upward flow component, but this component is reversed in the upper part of the aquifer during periods of high water levels in the Chena River. These periodic changes in the magnitude and direction of ground-water flow have a considerable influence on the transport of dissolved hydrocarbons in the subsurface. Both petroleum hydrocarbons and chlorinated solvents were found in ground water at the study area. Typical degradation products of these compounds were also found, indicating that biodegradation by indigenous microorganisms is occurring.

Water-Resources Investigations Report↗