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At least 523 records · Page 29Linked to original sources
USGS1986

Suspended sediment in Minnesota streams

Suspended-sediment samples have been collected by the U.S. Geological Survey from 115 sites on Minnesota streams since October 1960. Data from 42 sites were sufficient for characterizing sediment concentrations and yields. Average concentrations ranged from 4.4 milligrams per liter on the Baptism River in northeastern Minnesota to 190 milligrams per liter on the Root River in the southeast. Log-linear equations that describe the sediment-transport curve were developed for 33 daily sediment stations and used to estimate long-term sediment yields. Average annual yields ranged from less than 1.0 ton per square mile on the Pelican River, to more than 200 tons per square mile on the Root and Whitewater Rivers and Deer Creek. Estimates indicated that under extreme circumstances the average annual sediment load for 2 years could be transported in slightly more than one day. Analysis showed that more than 90 percent of the annual sediment load was carried during 3 to 9 months of the year. On the average, almost 25 percent of the annual sediment load was transported during April. Generally, it was found that less than 4 percent of the average annual load was transported during December, January, and February, which indicates that sampling frequency could be reduced during winter.

Minnesota↗
USGS1993

Chemical characteristics and temporal trends in eight streams of the Catskill Mountains, New York

Discharge to concentration relationships for eight streams studied by the U.S. Geological Survey (USGS) as part of the U.S. Environmental Protection Agency's (U.S. EPA) Long-Term Monitoring Project (1983-89) indicate acidification of some streams by H2SO4 and HNO3 in atmospheric deposition and by organic acids in soils. Concentrations of major ions in precipitation were similar to those reported at other sites in the northeastern United States. Average concentrations of SO42- and NO3- were similar among streams, but base cation concentrations differed widely, and these differences paralleled the differences in acid neutralizing capacity (ANC). Baseflow ANC is not a reliable predictor of stream acidity at high flow; some streams with high baseflow ANC (> 150 ??eq L-1) declined to near zero ANC at high flow, and one stream with low baseflow ANC (< 50 ??eq L-1) did not approach zero ANC as flow increased. Episodic decreases in ANC and pH during peak flows were associated with increased concentrations of NO3- and dissolved organic carbon (DOC). Aluminum concentrations exceeding 300 ??g L-1 were observed during peak flows in headwater streams of the Neversink River and Rondout Creek. Seasonal Kendall Tau tests for temporal trends indicate that SO42- concentrations in streamwater generally decreased and NO3- concentrations increased during the period 1983-1989. Combined acid anion concentrations (SO42- + NO3-) were generally unchanged throughout the period of record, indicating both that the status of these streams with respect to acidic deposition is unchanged, and that NO3- is gradually replacing SO42- as the dominant acid anion in the Catskill streams.Discharge to concentration relationships for eight streams studied by the US Geological Survey (USGS) as part of the Environmental Protection Agency's (US EPA) Long-term monitoring project (19831-89) indicate acidification of some streams by H2SO4 and HNO3 in atmospheric deposition and by organic acids in soils. Concentrations of major ions in precipitations were similar to those reported at other sites in the northeastern United States. Average concentrations of SO42- and No3- were similar among streams, but base cation concentrations differed widely, and these differences parallelel the differences in acid neutralizing capacity (ANC).

Water, Air, & Soil Pollution↗
USGS1949

Geology and ground-water hydrology of the Angostura irrigation project, South Dakota, with a section on the mineral quality of the waters

The lands to be irrigated from water stored in the Angostura Reservoir are situated on the lover of two terraces along the southeast side of the Cheyenne River in northeastern Fall River County and on the terrace known as Harrison Plat in southeastern Custer County, S. Dak. The terrace deposits are composed of relatively permeable sands and gravels that rest on a shale bedrock platform. The terrace surfaces are mantled in part by slope wash derived from higher shale slopes and by wind-blown sand. Ground water occurs under water-table conditions in the river alluvium and in terraces above the river. Although the zone of saturation in the terrace deposits is 6enerally thin, it is essentially continuous in the area southeast of the river, and the water issues as springs in the terrace faces along the inner valley of the river and along the valleys of tributary streams cuttin6 back into the terraces. A zone of saturation is present only in part of the Harrison Plat area, and it extends to the terrace face only along Cottonwood Creek. Wells in the unconsolidated mantle rock supply water for domestic and stock purposes, but yields are small. Abundant supplies of artesian water are available at depths ranging up to 3,000 feet but are not now utilized except at the extreme western end of the area where the bedrock aquifer is close below the surface. The effect of applying irrigation water on the terrace lands will depend on the character of the underlying material and on the measures taken to forestall waterlogging and other undesirable effects. Terrace areas that are mantled by slope wash will be especially susceptible to waterlogging, as will valley-bottom areas mantled by colluvium that are adjacent to irrigated terracea. Periodic measurements of water levels in observation wells will give warning of potential waterlogging in time to permit taking preventive measures. Analyses of samples of both ground water and surface water indicate a high mineral content. In general, samples from the Cheyenne River are higher in total dissolved solids and lower in percent sodium than the ground water.

South Dakota↗
USGS2018

Revised groundwater-flow model of the glacial aquifer system north of Aberdeen, South Dakota, through water year 2015

The city of Aberdeen, in northeastern South Dakota, requires an expanded and sustainable supply of water to meet current and future demands. Conceptual and numerical models of the glacial aquifer system in the area north of Aberdeen were developed by the U.S. Geological Survey in cooperation with the City of Aberdeen in 2012. The U.S. Geological Survey, in cooperation with the City of Aberdeen, completed a study to revise the original numerical groundwater-flow model using data through water year (WY) 2015 to aid the City of Aberdeen in their development of plans and strategies for a sustainable water supply and to increase understanding of the glacial aquifer system and groundwater-flow system near Aberdeen. The original model was revised to improve the fit between model-simulated values and observed (measured or estimated) data, provide greater insight into surface-water interactions, and improve the usefulness of the model for water-supply planning. The revised groundwater-flow model (hereafter referred to as the “revised model”) presented in this report supersedes the original model. The purpose of this report is to describe a revised groundwater-flow model including data collection, model calibration, and model results for the glacial aquifer system including the Elm, Middle James, and Deep James aquifers north of Aberdeen, South Dakota, using updated hydrologic data through WY 2015. The original numerical model was revised in several ways. The model was modified by adding four new layers, which included a surficial layer, two intervening confining layers, and a shale bedrock layer. The revised model provides an improved understanding of the groundwater-flow system in comparison to the original model. The principal aquifers of the model area include portions of the Elm, Middle James, and Deep James aquifers. The lithologic information used to define and describe the aquifers in the model area was unaltered; however, aquifer properties and boundary conditions were reviewed and updated using geological information reported by the South Dakota Department of Environmental and Natural Resources and information obtained from geophysical investigations for this study. The horizontal extent of the Elm, Middle James, and Deep James aquifers was unaltered from the original model. The thickness of the Deep James aquifer was modified based on interpretations from the geophysical investigations. In general, groundwater in the Elm aquifer flowed from northwest to southeast and locally towards rivers and streams. Similarly, in the Middle James and Deep James aquifers, groundwater also typically flowed southeast. The revisions made to the original model include use of the following MODFLOW stress packages: Recharge, Evapotranspiration, Time-Variant Specified Head, Wells, Drains, and Stream Flow Routing, all of which were updated from the original model except for the Stream Flow Routing Package, which replaced the River Package used in the original model. Model calibration is the process of estimating model parameters to minimize the differences, or residuals, between observed data and simulated values; therefore, Parameter ESTimation (PEST) software was used to optimize model input parameters by matching model-simulated values to observed data. Calibration parameters included horizontal hydraulic conductivity, vertical hydraulic conductivity, specific yield, specific storage, and vertical streambed conductance for stream and drain cells. Multipliers were used to calibrate the recharge and evapotranspiration stresses. Evapotranspiration extinction depth also was adjusted during model calibration. Comparisons to the original model are described to highlight the changes made in the revised model. In general, the revised model adequately simulates the natural system and compares favorably with observed hydrologic data. Simulated water levels were evaluated by comparing them to single water-level observations at selected well locations. The selected wells were the same wells used in the original model. The coefficient of determination value between simulated and observed water levels for the revised model was 0.89 and included simulated and observed values from October 1, 1974 (WY 1975), through September 30, 2015 (WY 2015). The coefficient of determination value for the original model was 0.94 and included simulated and observed values from October 1, 1974, through September 30, 2009. The difference may indicate that the original model could have been overfit to hydraulic head observations because base flow was not simulated. The additional data used in the revised model included some climatically wetter, more extreme periods, such as 2011, in which annual precipitation was 30.9 inches. Average annual precipitation for the original model timeframe, which included data from WYs 1975–2009, was 20.26 inches. Additional precipitation data for WYs 2010–15, included in the revised model timeframe, resulted in an average annual precipitation for WYs 1975–2015 in the model area of 20.6 inches. The larger variability in climate data coupled with the additional water-level data could explain the lower coefficient of determination for water levels in the revised model. The revised model was used to calculate various groundwater-budget components for steady-state and transient conditions for WYs 1975–2015. The time-variant specified-head cells in the revised model had the largest change when compared to the original steady-state model for inflows and outflows. Comparing the transient budget components between the original and the revised models indicated that inflow from recharge and time-variant specified-head cells had the greatest effect on groundwater inflows, and outflow from storage had the greatest effect on groundwater outflows. The simulated potentiometric contours from the revised model were compared with (1) the observed (interpreted) potentiometric surface (layer 2) and the hydraulic head values (layers 4 and 6) and (2) the simulated contours from the original model. The simulated hydraulic gradients and general direction of groundwater flow in the Elm aquifer in the revised model generally matched the observed potentiometric contours, the simulated potentiometric contours from the original model, and general flow directions interpreted to be perpendicular to the contours. Minor discrepancies between simulated potentiometric contours from the revised model and the observed potentiometric contours may be due to the lack of observed data in the model area. The revised model was designed to reduce the limitations of the original model. The revisions were validated by comparing the results of the original model with the revised model. A primary benefit of the revised model is the inclusion of the surficial deposits and the confining units as explicit layers in the model. The addition of the surficial layer was beneficial for three primary reasons: (1) more accurate representation of recharge from precipitation, (2) more accurate representation of groundwater evapotranspiration, and (3) more accurate representation of groundwater and surface-water interactions. The groundwater model is a numeric approximation of a complex physical hydrologic system, and the revised model data were interpolated in regions with sparse data. Additionally, model discretization included averaged and interpolated values for water use, withdrawal rates, and hydraulic conductivity. The revised model provides a useful estimate for hydraulic gradients, groundwater-flow directions, and aquifer response to groundwater withdrawals.

South Dakota↗
USGS2007

Hydrogeologic Framework and Ground-Water Budget of the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources and Washington State Department of Ecology, investigated the hydrogeologic framework and ground-water budget of the Spokane Valley-Rathdrum Prairie (SVRP) aquifer located in northern Idaho and northeastern Washington. Descriptions of the hydrogeologic framework, water-budget components, and further data needs are provided. The SVRP aquifer, which covers about 370 square miles including the Rathdrum Prairie, Idaho, and the Spokane Valley and Hillyard Trough, Washington, is the sole source of drinking water for more than 500,000 residents. Continued growth, water-management issues, and potential effects on water availability and water quality in the aquifer and in the Spokane and Little Spokane Rivers have illustrated the need to better understand and manage the region's water resources. The SVRP aquifer consists mostly of gravels, cobbles, and boulders - deposited during a series of outburst floods resulting from repeated collapse of the ice dam that impounded ancient Glacial Lake Missoula. In most places, the SVRP aquifer is bounded by bedrock of pre-Tertiary granite or metasedimentary rocks, or Miocene basalt and associated sedimentary deposits. Discontinuous fine-grained layers are scattered throughout the SVRP aquifer at considerably different altitudes and with considerably different thicknesses. In the Hillyard Trough and the Little Spokane River Arm of the aquifer, a massive fine-grained layer with a top altitude ranging from about 1,500 to 1,700 feet and thickness ranging from about 100 to 200 feet separates the aquifer into upper and lower units. Most of the Spokane Valley part of the aquifer is devoid of fine-grained layers except near the margins of the valley and near the mouths of lakes. In the Rathdrum Prairie, multiple fine-grained layers are scattered throughout the aquifer with top altitudes ranging from about 1,700 to 2,400 feet with thicknesses ranging from 1 to more than 135 feet. The altitude of the base of the aquifer ranges from less than 1,800 feet near Lake Pend Oreille to less than 1,200 feet near the aquifer's outlet near Long Lake. The thickness of the aquifer is more than 800 feet in the northwestern part of the northern Rathdrum Prairie, through the West Channel area, and through the west-central part of the Rathdrum Prairie. In Washington, the areas of greatest thickness, more than 600 feet, are mapped in the central parts of the Spokane Valley, Spokane, and the Hillyard Trough. Recharge or inflow to the SVRP aquifer occurs from six main sources: the Spokane River, lakes, infiltration from precipitation over the aquifer, tributaries, infiltration from landscape irrigation and septic systems, and subsurface inflow. Discharge or outflow from the SVRP aquifer occurs from five main sources: the Spokane River, the Little Spokane River, pumpage, subsurface discharge to Long Lake, and infiltration of ground water to sewers. Total estimated mean annual inflow to and outflow from the SVRP aquifer is about 1,470 cubic feet per second. Several data needs were identified during this investigation that would improve the definition of the hydrogeologic framework and ground-water budget components for the SVRP aquifer study area. Deep drilling along the axis of the aquifer could determine the depth to the bottom of the aquifer where data are currently unavailable as well as identify the presence of fine-grained layers and their thickness. A more detailed analysis of the geologic and hydrologic setting near the southern ends of Spirit and Hoodoo Valleys could help determine the location of the ground-water divide between the two valleys and the Rathdrum Prairie. Better estimates of seepage into the aquifer from Coeur d'Alene Lake and Lake Pend Oreille and underflow from the aquifer to Long Lake would strengthen the recharge and discharge estimates of the aquifer. A hydrochemical study incorporating analyses of envi

Scientific Investigations Report↗
USGS1987

An evaluation of the bedrock aquifer system in northeastern Wisconsin

Ground water is a major source of water in northeastern Wisconsin. The lower Fox River valley, located between Lake Winnebago and Green Bay in northeastern Wisconsin, is the second largest population center in Wisconsin. By 1957, ground-water withdrawals had lowered the potentiometric surface of the aquifer system as much as 440 feet below prepumping levels. With the exception of the city of Green Bay, which converted from ground water to surface water (Lake Michigan) for their municipal water supply in 1957, ground-water withdrawals have continually increased. The report evaluates the bedrock aquifer system in northeastern Wisconsin and describes how the flow regimes in the system have been altered due to ground-water withdrawals. A three-dimensional finite-difference groundwater flow model was used to aid in evaluation of the regional flow system. In order to simplify the study of the aquifer system, the geologic units were grouped into eight geohydrologic units consisting of four aquifers and four confining beds. The aquifers are the more permeable sand and gravel layers in the surficial deposits (aquifer 4), Devonian dolomite-Silurian dolomite (aquifer 3), St. Peter Sandstone- Prairie du Chien Group-Jordan Sandstone Member of the Trempealeau Formation (aquifer 2), and the Galesville Sandstone-Eau Claire Sandstone-Mount Simon Sandstone (aquifer 1). The confining beds are the less permeable silts and clays in the surficial deposits (confining bed 4), Maquoketa Shale-Galena Dolomite-Decorah Shale-Platteville Formation (confining bed 3), St. Lawrence Member of the Trempealeau Formation-Franconia Sandstone (confining bed 2), and the Precambrian crystalline rock (confining bed 1). The following aquifer and confining-bed characteristics were determined to represent the aquifer system of northeastern Wisconsin and were used in the development of the model. Aquifer 4 acts as an upper boundary of the bedrock aquifer system. The hydraulic conductivity of aquifer 3 was 7.9 feet per day and the storage coefficient was estimated to be 0.01. Transmissivity input values to the model for aquifer 2 are based on hydraulic conductivities ranging from 3 to 8 feet per day. The storage coefficient for aquifer 2 was 0.0002. The transmissivity input values to the model for aquifer 1 are based on hydraulic conductivities ranging from 2.5 to 8 feet per day and the storage coefficient was 0.0002. Confining bed 4 acts as an upper confining unit for the underlying bedrock aquifers. A vertical hydraulic conductivity of 0.007 foot per day was assigned to represent confining bed 4. The vertical hydraulic conductivity of confining bed 3 was assigned values of 0.0001 to 0.000004 foot per day. A value of 0.00001 foot per day was used as the vertical hydraulic conductivity for confining bed 2. Confining bed 1 is a lower boundary of the system and was not modeled. Model simulations indicate that, by 1914, ground-water withdrawals from the aquifer system had already impacted the study area. Pumping in the Green Bay metropolitan area had lowered the potentiometric heads in aquifer 1 by 69 feet and in aquifer 2 by 55 feet. Model simulations indicate that, by 1981, ground-water withdrawals have caused a cone of depression centered in the city of De Pere area. The influence of the cone affects almost the entire study area and has significantly altered the horizontal and vertical flow regimes in the aquifer system. In 1981, computed drawdowns below the prepumping potentiometric surface of aquifer 1 range from 0 feet on the western side of the study area to 330 feet in the center of the cone of depression. In aquifer 2, the computed drawdown ranges from 0 feet on the western side of the study area to 253 feet in the center of the cone.

Wisconsin↗
USGS2002

Geologic map of the Frisco quadrangle, Summit County, Colorado

New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift?partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts the northeastern corner of the quadrangle. The oldest rocks in the quadrangle underlie the Tenmile Range and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, Ogden, 1987, Rock units of the Precambrian- basement in Colorado: U.S. Geological Survey Professional Paper 1321-A, 54 p.). The oldest sedimentary unit is the Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. The sedimentary rocks are intruded by sills and dikes of dacite porphyry sills of Swan Mountain, dated at 44 Ma (Marvin, R.F., Mehnert, H.H., Naeser, C.W., and Zartman, R.E., 1989, U.S. Geological Survey radiometric ages, compilation ?C??Part five?Colorado, Montana, Utah, and Wyoming: Isochron/West, no. 53, p. 14-19. Simmons, E.C., and Hedge, C.E., 1978, Minor-element and Sr-isotope geochemistry of Tertiary stocks, Colorado mineral belt: Contributions to Mineralogy and Petrology, v. 67, p. 379-396.). Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Tertiary, on the south flank of Tenderfoot Mountain, (2) deeply weathered, very coarse gravel deposits, mostly along Gold Run and underlying Mesa Cortina; the gravels are gold bearing and were mined by hydraulic methods in the 1800's, (3) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene) that were derived from large valley glaciers that flowed down Tenmile and North Tenmile Creeks; the town of Frisco is underlain mostly by Pinedale-age glacial outwash, (4) recent landslide deposits, including one large (about 1 square kilometer) area just downslope from Lilly Pad Lake, west of I-70, and (5)extensive colluvial and alluvial deposits. The latest seismic events appear to be middle Pliestocene in age and are associated with small scarps that cut Bull Lake till but do not cut Pinedale till.

Miscellaneous Field Studies Map↗
USGS2001

Assessment method for epithermal gold deposits in northeast Washington State using weights-of-evidence GIS modeling

The weights-of-evidence analysis, a quantitative mineral resource mapping tool, is used to delineate favorable areas for epithermal gold deposits and to predict future exploration activity of the mineral industry for similar deposits in a four-county area (222 x 277 km), including the Okanogan and Colville National Forests of northeastern Washington. Modeling is applied in six steps: (1) building a spatial digital database, (2) extracting predictive evidence for a particular deposit, based on an exploration model, (3) calculating relative weights for each predictive map, (4) combining the geologic evidence maps to predict the location of undiscovered mineral resources and (5) measuring the intensity of recent exploration activity by use of mining claims on federal lands, and (6) combining mineral resource and exploration activity into an assessment model of future mining activity. The analysis is accomplished on a personal computer using ArcView GIS platform with Spatial Analyst and Weights-of-Evidence software. In accord with the descriptive model for epithermal gold deposits, digital geologic evidential themes assembled include lithologic map units, thrust faults, normal faults, and igneous dikes. Similarly, geochemical evidential themes include placer gold deposits and gold and silver analyses from stream sediment (silt) samples from National Forest lands. Fifty mines, prospects, or occurrences of epithermal gold deposits, the training set, define the appropriate a really-associated terrane. The areal (or spatial) correlation of each evidential theme with the training set yield predictor theme maps for lithology, placer sites and normal faults. The weights-of-evidence analysis disqualified the thrust fault, dike, and gold and silver silt analyses evidential themes because they lacked spatial correlation with the training set. The decision to accept or reject evidential themes as predictors is assisted by considering probabilistic data consisting of weights and contrast values calculated for themes according to areal correlation with the training sites. Predictor themes having acceptable weights and contrast values are combined into a preliminary model to predict the locations of undiscovered epithermal gold deposits. This model facilitates ranking of tracts as non-permissive, permissive or favorable categories based on exclusionary, passive, and active criteria through evaluation of probabilistic data provided by interaction of predictor themes. The method is very similar to the visual inspection method of drawing conclusions from anomalies on a manually overlain system of maps. This method serves as a model for future mineral assessment procedures because of its objective nature. To develop a model to predict future exploration activity, the locations of lode mining claims were summarized for 1980, 1985, 1990, and 1996. Land parcels containing historic claims were identified either as those with mining claims present in 1980 or valid claims present in 1985. Current claim parcels were identified as those containing valid lode claims in either 1990 or 1996. A consistent parcel contains both historic and current claims. The epithermal gold and mining claim activity models were combined into an assessment (or mineral resource-activity) model to assist in land use decisions by providing a prediction of mineral exploration activity on federal land in the next decade. Ranks in the assessment model are: (1) no activity, (2) low activity, (3) low to moderate activity, (4) moderate activity and (5) high activity.

Washington↗
USGS2000

Ground-water quality and vulnerability to contamination in selected agricultural areas of southeastern Michigan, northwestern Ohio, and northeastern Indiana

Ground-water quality was assessed in the northeastern part of the Corn Belt, where tile-drained row crops are underlain by fractured glacial till. Data were collected from 30 shallow monitor wells and 18 co-located domestic wells as part of the U.S. Geological Survey’s National Water- Quality Assessment in the Lake Erie-Lake St. Clair Basin. Pesticides or pesticide degradates were detected in 41 percent of the monitor wells and 6 percent of the domestic wells. The pesticides detected closely correspond to those most heavily applied—herbicides used on corn and soybeans. Pesticide degradates were detected three times more frequently, and at higher concentrations, than were parent compounds. No pesticide concentration exceeded a USEPA Maximum Contaminant Level (MCL), but MCL’s have not been established for 9 of the 11 compounds detected. Thirty-seven percent of monitor-well samples had nitrate concentrations indicative of human influences such as fertilizer, manure or septic systems. Nitrate was the only chemical constituent detected at a concentration greater than an MCL. The MCL was exceeded in 7 percent of samples from monitor wells which were too shallow to be used as a source of drinking water. Pesticide and nitrate concentrations in the study area are low relative to other agricultural areas of the Nation. Several authors have suggested that ground water in parts of the Upper Midwest is minimally contaminated because it is protected by the surficial glacial till or tile drains. These ideas are examined in light of the relations between concentration, well depth, and groundwater age in the study area. Most of the shallow ground water is hydraulically connected to the land surface, based on the observations that 83 percent of waters from monitor wells were recharged after 1953, and 57 percent contained a pesticide or an elevated nitrate concentration. Fractures or sand-and-gravel stringers within the till are the probable pathways. In some areas, deeper parts of the groundwater- flow system are also hydraulically connected to the land surface. Almost half the waters from wells 50 to 100 feet deep were recharged after 1953. Anthropogenic constituents were detected in samples from three domestic wells 60 to 121 feet deep, in areas where the till is relatively coarse-grained. The hydrogeologic system has several geochemical characteristics conducive to transformations or sorption of nitrate or pesticides: (1) the till is clay-rich, has a high organic-carbon content, and contains an abundance of pyrite-rich shale fragments, (2) the ground water has low dissolved- oxygen concentrations, and (3) iron and manganese oxides and oxyhyroxides line the faces of fractures in the unsaturated zone. Although the aquifer system appears be protected from contamination in some areas, the fact that the surficial till is heterogeneous and of variable thickness suggests that the protection is not uniform. The protection can be breached by fractures or sand-and-gravel stringers, which are apparent in core samples but not noted on domestic-well logs.

Indiana, Michigan, Ohio↗
USGS2013

Sediment distribution and hydrologic conditions of the Potomac aquifer in Virginia and parts of Maryland and North Carolina

Sediments of the heavily used Potomac aquifer broadly contrast across major structural features of the Atlantic Coastal Plain Physiographic Province in eastern Virginia and adjacent parts of Maryland and North Carolina. Thicknesses and relative dominance of the highly interbedded fluvial sediments vary regionally. Vertical intervals in boreholes of coarse-grained sediment commonly targeted for completion of water-supply wells are thickest and most widespread across the central and southern parts of the Virginia Coastal Plain. Designated as the Norfolk arch depositional subarea, the entire sediment thickness here functions hydraulically as a single interconnected aquifer. By contrast, coarse-grained sediment intervals are thinner and less widespread across the northern part of the Virginia Coastal Plain and into southern Maryland, designated as the Salisbury embayment depositional subarea. Fine-grained intervals that are generally avoided for completion of water-supply wells are increasingly thick and widespread northward. Fine-grained intervals collectively as thick as several hundred feet comprise two continuous confining units that hydraulically separate three vertically spaced subaquifers. The subaquifers are continuous northward but merge southward into the single undivided Potomac aquifer. Lastly, far southeastern Virginia and northeastern North Carolina are designated as the Albemarle embayment depositional subarea, where both coarse- and fine-grained intervals are of only moderate thickness. The entire sediment thickness functions hydraulically as a single interconnected aquifer. A substantial hydrologic separation from overlying aquifers is imposed by the upper Cenomanian confining unit. Potomac aquifer sediments were deposited by a fluvial depositional complex spanning the Virginia Coastal Plain approximately 100 to 145 million years ago. Westward, persistently uplifted granite and gneiss source rocks sustained a supply of coarse-grained sand and gravel. Immature, high-gradient braided streams deposited longitudinal bars and channel fills across the Norfolk arch subarea. By contrast, across the Salisbury and Albemarle embayment subareas, mature, medium- to low-gradient meandering streams deposited medium- to coarse-grained channel fills and point bars segregated from fine-grained overbank deposits. The Virginia depositional complex merged northward across the Salisbury embayment subarea with another complex in Maryland. Here, additional sediments were received from schist source rocks that underwent three cycles of initial uplift and rapid erosion followed by crustal stability and erosional leveling. Because of the predominance of coarse-grained sediments, transmissivity, hydraulic conductivity, and regional velocities of lateral flow through the Potomac aquifer are greatest across the Norfolk arch depositional subarea, but decrease progressively northward with increasingly fine-grained sediments. Confining units hydraulically separate the Potomac aquifer from overlying aquifers, as indicated by large vertical hydraulic gradients. By contrast, most of the Potomac aquifer internally functions hydraulically as a single interconnected aquifer, as indicated by uniformly small vertical gradients. Most fine-grained sediments within the aquifer do not hydraulically separate overlying and underlying coarse-grained sediments. Across the Salisbury embayment depositional subarea, however, hydraulic separation among the vertically spaced subaquifers is imposed by the intervening confining units. The Potomac aquifer is the largest and most heavily used source of groundwater in the Virginia Coastal Plain. Water-level declines as great as 200 feet create the potential for saltwater intrusion. Conventional stratigraphic correlation has been generally ineffective at accurately characterizing complexly distributed fluvial sediments that compose the Potomac aquifer. Consequently, the aquifer’s internal hydraulic connectivity and overall hydrologic function have not been well understood. Water-supply planning and development efforts have been hampered, and interpretations of regulatory criteria for allowable water-level declines have been ambiguous. An investigation undertaken during 2010–11 by the U.S. Geological Survey, in cooperation with the Virginia Department of Environmental Quality, provides a comprehensive regional description of the spatial distribution of Potomac aquifer sediments and their relation to hydrologic conditions. Altitudes and thicknesses of 2,725 vertical sediment intervals represent the spatial distribution of Potomac aquifer sediments in the Virginia Coastal Plain and adjacent parts of Maryland and North Carolina. Sediment intervals are designated as either dominantly coarse or fine grained and were determined by interpretation of geophysical logs and ancillary information from 456 boreholes. Sediment-interval and borehole summary statistical data indicate regional trends in sediment lithology and stratigraphic continuity, upon which three structurally based and hydrologically distinct sediment depositional subareas are designated. Broad patterns of sediment deposition over time are inferred from published sediment pollen-age data. Discrepancies in previously drawn hydrostratigraphic relations between southeastern Virginia and northeastern North Carolina are partly resolved based on borehole geophysical logs and a recently documented geologic map and corehole. A conceptual model theorizes the depositional history of the sediments and geologically accounts for their distribution. Documented pumping tests of the Potomac aquifer at 197 locations produced 336 values of transmissivity and 127 values of storativity. Based on effective aquifer thicknesses, 296 values of sediment hydraulic conductivity and 113 values of sediment specific storage are calculated. Vertical hydraulic gradients are calculated from 9,479 pairs of water levels measured between November 17, 1953, and October 4, 2011, in 129 closely spaced pairs of wells. Borehole sediment-interval and related data provide a means to achieve high yielding production wells in the Potomac aquifer by site-specific targeting of drilling operations toward water-bearing coarse-grained sand and gravel. Advance knowledge of the potential of different parts of the aquifer also aids in planning optimal groundwater-development areas. Depositional subareas further provide a possible context for resource management. Current (2013) regulatory limits on water-level declines are relative to top surfaces of subdivided upper, middle, and lower Potomac aquifers across the entire Virginia Coastal Plain, but have the potential to exceed the same limit relative to a single undivided Potomac aquifer. By contrast, designation of the sediments as a single aquifer in the Norfolk arch and Albemarle embayment subareas—and as a series of vertically spaced subaquifers and intervening confining units in the Salisbury embayment subarea—best reflects understanding of the Potomac aquifer and can avoid the potential for excessive water-level declines. Simulation modeling to evaluate effects of groundwater withdrawals could be designed similarly, including vertical discretization and (or) zonation of the Potomac aquifer based on depositional subareas and a geostatistical distribution of aquifer properties derived from borehole sediment-interval data. Further resource-management information needs extend beyond the developed part of the Potomac aquifer, particularly across the Northern Neck and Middle Peninsula where only the shallowest part of the aquifer is known, and include structural aspects such as faults, basement bedrock, and the Chesapeake Bay impact crater.

Maryland, North Carolina, Virginia↗
USGS2016

Geologic and geophysical maps and volcanic history of the Kelton Pass SE and Monument Peak SW Quadrangles, Box Elder County, Utah

The Kelton Pass SE and Monument Peak SW 7.5' quadrangles are located in Box Elder County, northwestern Utah (figure 1; plate 1). The northern boundary of the map area is 8.5 miles (13.7 km) south of the Utah-Idaho border, and the southern boundary reaches the edge of mud flats at the north end of Great Salt Lake. Elevations range from 4218 feet (1286 m) along the mud flats to 5078 feet (1548 m) in the Wildcat Hills. Deep Creek forms a prominent drainage between the Wildcat Hills and Cedar Hill. The closest towns are the ranching communities of Snowville, Utah (10 miles [16 km] to the northeast) (figure 1), and Park Valley, Utah (10 miles [16 km] to the west). The Kelton Pass SE and Monument Peak SW 7.5' quadrangles are located entirely within southern Curlew Valley, which drains south into Great Salt Lake, and extends north of the area shown on figure 1 into Idaho. Curlew Valley is bounded on the west by the Raft River Mountains and on the east by the Hansel Mountains (figure 1). Sedimentary and volcanic bedrock exposures within the quadrangles form the Wildcat Hills, Cedar Hill, and informally named Middle Shield (figure 1). Exposed rocks and deposits are Permian to Holocene in age, and include the Permian quartz sandstone and orthoquartzite of the Oquirrh Formation (Pos), tuffaceous sedimentary rocks of the Miocene Salt Lake Formation (Ts), Pliocene basaltic lava flows (Tb) and dacite (Tdw), Pleistocene rhyolite (Qrw) and basalt (Qb), and Pleistocene and Holocene surficial deposits of alluvial, lacustrine, and eolian origin. Structurally, the map area is situated in the northeastern Basin and Range Province, and is inferred to lie within the hanging wall of the late Miocene detachment faults exposed in the Raft River Mountains to the northwest (e.g., Wells, 1992, 2009; figure 1). This mapping project was undertaken to produce a comprehensive, large-scale geologic map of the Wildcat Hills, as well as to improve understanding of the volcanic and tectonic evolution of southern Curlew Valley. The resultant publication includes a geologic map of the Kelton Pass SE and Monument Peak SW quadrangles (plate 1), two interpretive geologic cross sections (plate 2), new geophysical data and interpretations, and new geochronology data for volcanic units within and near the quadrangles.

Utah↗
USGS1994

Selected ground-water information for the Columbia Plateau Regional Aquifer System, Washington and Oregon, 1982-1985; Volume III, Ground-water quality data

The data report presents ground-water information collected and analyzed as part of the U.S. Geological Survey's Columbia Plateau Regional Aquifer-System Analysis Program. The information was gathered from July 1982 through September 1985 in the part of the aquifer system located in central and eastern Washington and north-central and northeastern Oregon. The report consists of three volumes: volume I, geohydrology; volume II, water levels; and volume III, ground-water quality. This volume, III, presents ground-water quality data gathered from about 570 wells during the study.

Open-File Report↗
USGS2011

Hydrogeologic framework, groundwater movement, and water budget in the Chimacum Creek basin and vicinity, Jefferson County, Washington

This report presents information used to characterize the groundwater flow system in the Chimacum Creek basin. It includes descriptions of the geology and hydrogeologic framework; groundwater recharge and discharge; groundwater levels and flow directions; seasonal fluctuations in groundwater level; interactions between aquifers and the surface-water system; and a groundwater budget. The study area covers 124 square miles in northeastern Jefferson County, Washington, and includes the Chimacum Creek basin, which drains an area of about 37 square miles. The area is underlain by a north-thickening sequence of unconsolidated glacial and interglacial deposits that overlie sedimentary and igneous bedrock units that crop out along the margins and western interior of the study area. Six hydrogeologic units consisting of unconsolidated aquifers and confining units, along with an underlying bedrock unit, were identified. A surficial hydrogeologic map was developed and used with well information from 187 drillers' logs to construct 4 hydrogeologic sections, and maps showing the extent and thickness of the units. Natural recharge was estimated using precipitation-recharge relation regression equations developed for western Washington, and estimates were calculated for return flow from data on domestic indoor and outdoor use and irrigated agriculture. Results from synoptic streamflow measurements and water table elevations determined from monthly measurements at monitoring wells are presented and compared with those from a study conducted during 2002-03. A water budget was calculated comprising long-term average recharge, domestic public-supply withdrawals and return flow, self-supplied domestic withdrawals and return flow, and irrigated agricultural withdrawals and return flow.

Washington↗
USGS2001

Characteristics of water, sediment, and benthic communities of the Wolf River, Menominee Indian Reservation, Wisconsin, water years 1986-98

Analyses and interpretation of water quality, sediment, and biological data from water years 1986 through 1998 indicated that land use and other human activities have had only minimal effects on water quality in the Wolf River upstream from and within the Menominee Indian Reservation in northeastern Wisconsin. Relatively high concentrations of calcium and magnesium (natural hardness), iron, manganese, and aluminum were measured in Wolf River water samples during water years 1986-98 from the three sampled sites and attributed to presence of highly mineralized geologic materials in the basin. Average calcium and magnesium concentrations varied from 22-26 milligrams per liter (mg/L) and 11-13 mg/L, respectively. Average iron concentrations ranged from 290-380 micrograms per liter ( μ g/L); average manganese concentrations ranged from 53-56 mg/L. Average aluminum concentrations ranged from 63-67 μ g/L. Mercury was present in water samples but concentrations were not at levels of concern. Levels of Kjeldahl nitrogen, ammonia, nitrite plus nitrate, total phosphorus, and orthophosphorus in water samples were often low or below detection limits (0.01- 0.10 mg/L). Trace amounts of atrazine (maximum concentration of 0.031 μ g/L), deethylatrazine (maximum 0.032 μ g/L), and alachlor (maximum of 0.002 μ g/L) were detected. Low concentrations of most trace elements were found in streambed sediment. Tissues of fish and aquatic invertebrates collected once each year from 1995 through 1998 at the Langlade and Keshena sites, near the northern and southern boundaries of the Reservation, respectively, were low in concentrations of most trace elements. Arsenic and silver in fish livers from both sites were less than or equal to 2 μ g/g arsenic and less than 1 μ g/g silver for dry weight analysis, and concentrations of antimony, beryllium, cadmium, cobalt, lead, nickel, and uranium were all below detection limits (less than 1 μ g/g dry weight). Concentrations of most other trace elements in fish were low, with the exceptions of chromium, copper, mercury, and selenium; however, these concentrations are not at levels of concern. Concentrations of all trace elements analyzed in whole caddisfly larvae also were low compared to those reported in the literature. During 1998, a total of 48 species of macroinvertebrates were identified at each of two sampled sites, with similar numbers of genera represented at both: 41 at Keshena and 44 at Langlade. The percentage EPT (Ephemeroptera, Plecoptera, and Trichoptera) was 52 at Keshena and 77 at Langlade; these relatively large percentages suggest very good to excellent water quality at these sites. A total of 52 algal taxa were identified at the Wolf River near Langlade. Diatoms made up 96 percent of the algal biomass. A total of 58 algal taxa were identified at Keshena, including 48 diatom taxa (83 percent). Although diatoms accounted for just 22 percent of the algal relative abundance, in cells per square centimeter, diatoms contributed 91 percent of the total algal biomass. The overall biological integrity of the Keshena and Langlade sites, based on diversity, siltation, and pollution indexes for diatoms is excellent.

Wisconsin↗
USGS2001

Water resources of the Lake Traverse Reservation, South and North Dakota, and Roberts County, South Dakota

In 1994, the U.S. Geological Survey, in cooperation with the Sisseton-Wahpeton Sioux Tribe; Roberts County; and the South Dakota Department of Environment and Natural Resources, Geological Survey Program, began a 6-year investigation to describe and quantify the water resources of the area within the 1867 boundary of the Lake Traverse Reservation and adjacent parts of Roberts County. Roberts County is located in extreme northeastern South Dakota, and the 1867 boundary of the Lake Traverse Reservation encompasses much of Roberts County and parts of Marshall, Day, Codington, and Grant Counties in South Dakota and parts of Richland and Sargent Counties in southeast North Dakota. This report includes descriptions of the quantity, quality, and availability of surface and ground water, the extent of the major glacial and bedrock aquifers and named outwash groups, and surface- and ground-water uses within the 1867 boundary of the Lake Traverse Reservation and adjacent parts of Roberts County. The surface-water resources within the 1867 boundary of the Lake Traverse Reservation and adjacent parts of Roberts County include rivers, streams, lakes, and wetlands. The Wild Rice and Bois de Sioux Rivers are tributaries of the Red River within the Souris-Red-Rainy River Basin; the Little Minnesota, Jorgenson, and North Fork Whetstone Rivers are tributaries of the Minnesota River within the Upper Mississippi River Basin, and the James and Big Sioux Rivers are tributaries within the Missouri River Basin. Several of the larger lakes within the study area have been developed for recreation, while many of the smaller lakes and wetlands are used for livestock watering or as wildlife production areas. Statistical summaries are presented for the water-quality data of six selected streams within the study area, and the dominant chemical species are listed for 17 selected lakes within the study area. The glacial history of the study area has led to a rather complex system of glacial aquifers. The boundaries of 11 aquifers and 6 named outwash groups were delineated based on hydrogeologic cross sections, water levels, and water-quality similarities/dissimilarities. The glacial aquifers include Coteau Lakes system, Big Sioux, Alta-mont, Revillo, James, Veblen system, Spiritwood, Hankinson, Rosholt, Milnor Channel, and Fairmount; the bedrock aquifer included in this report is the Dakota. Named outwash groups include the Prairie Coteau, Lonesome Lake, Marday, Eden, Roslyn, and Wilmot. A summary of the character-istics of each of the major aquifers and outwash groups and a summary of selected chemical analyses for each aquifer and outwash group are presented. All aquifers and outwash groups in the study area have either moderately hard or very hard water and are considered fresh to slightly saline. One or more water samples from some of the aquifers and outwash groups have a constituent that was above the recommended or mandatory limit for drinking water. Most aquifers and outwash groups have dissolved solids and sulfate contents above the recommended levels of 500 and 250 mg/L (milligrams per liter), respectively. The Dakota aquifer was the only one to have a mean chloride concentration above the recommended level of 250 mg/L. Nitrate concentrations greater than the mandatory limit of 10 mg/L were found in the Big Sioux aquifer and the Coteau Lakes and Veblen aquifer systems. Concentrations of arsenic greater than 10 ?g/L (micrograms per liter) were found in the Coteau Lakes and Veblen aquifer systems, and in the Rosholt and Fairmount aquifers. Municipalities and rural water systems currently provide most of the water used in the study area-nearly all of it from ground-water sources. Surface-water use is limited to livestock watering. About 55 percent of the total water used in Roberts County is for domestic purposes, with most domestic users served by a public supply system. Irrigation accounts for about 10 percent of the total water used. All

North Dakota, South Dakota↗
USGS2013

Meeting the Science Needs of the Nation in the Wake of Hurricane Sandy-- A U.S. Geological Survey Science Plan for Support of Restoration and Recovery

n late October 2012, Hurricane Sandy came ashore during a spring high tide on the New Jersey coastline, delivering hurricane-force winds, storm tides exceeding 19 feet, driving rain, and plummeting temperatures. Hurricane Sandy resulted in 72 direct fatalities in the mid-Atlantic and northeastern United States, and widespread and substantial physical, environmental, ecological, social, and economic impacts estimated at near $50 billion. Before the landfall of Hurricane Sandy, the USGS provided forecasts of potential coastal change; collected oblique aerial photography of pre-storm coastal morphology; deployed storm-surge sensors, rapid-deployment streamgages, wave sensors, and barometric pressure sensors; conducted Light Detection And Ranging (lidar) aerial topographic surveys of coastal areas; and issued a landslide alert for landslide prone areas. During the storm, Tidal Telemetry Networks provided real-time water-level information along the coast. Long-term network and rapid-deployment real-time streamgages and water-quality monitors reported on river levels and changes in water quality. Immediately after the storm, the USGS serviced real-time instrumentation, retrieved data from over 140 storm-surge sensors, and collected other essential environmental data, including more than 830 high-water marks mapping the extent and elevation of the storm surge. Post-storm lidar surveys documented storm impacts to coastal barriers informing response and recovery and providing a new baseline to assess vulnerability of the reconfigured coast. The USGS Hazard Data Distribution System served storm related information from many agencies on the Internet on a daily basis. This science plan was developed immediately following Hurricane Sandy to coordinate continuing USGS activities with other agencies and to guide continued data collection and analysis to ensure support for recovery and restoration efforts. The data, information, and tools that are produced by implementing this plan will: (1) further characterize impacts and changes, (2) guide mitigation and restoration of impacted communities and ecosystems, (3) inform a redevelopment strategy aimed at developing resilient coastal communities and ecosystems, (4) improve preparedness and responsiveness to the next hurricane or similar coastal disaster, and (5) enable improved hazard assessment, response, and recovery for future storms along the hurricane prone shoreline of the United States. The activities outlined in this plan are organized in five themes based on impact types and information needs. These USGS science themes are: Theme 1: Coastal topography and bathymetry. Theme 2: Impacts to coastal beaches and barriers. Theme 3: Impacts of storm surge and estuarine and bay hydrology. Theme 4: Impacts on environmental quality and persisting contaminant exposures. Theme 5: Impacts to coastal ecosystems, habitats, and fish and wildlife. A major emphasis in the implementation of this plan will be on interacting with stakeholders to better understand their specific data and information needs, to define the best way to make information available, and to support applications of USGS science and expertise to decisionmaking.

Connecticut;Delaware;Maine;Maryl;Massachusetts;New↗
USGS1995

Geologic map of the Littlefield Quadrangle, northern Mohave County, Arizona

The Littlefield 7.5' quadrangle lies in the extreme northwestern corner of Mohave County, Arizona (fig. 1). Elevations range from about 536.5 m (1,760 ft) at the Virgin River (south-central edge of quadrangle) to 975 m (3,200 ft) in the Beaver Dam Mountains (northeastern corner of quadrangle). Interstate Arizona Highway 15 and U.S. Highway 91 provides a general access to the quadrangle while several unimproved dirt roads lead to remote areas of the quadrangle. The community of Littlefield, Arizona is just southeast of Interstate 15 along the west bank of the Virgin River, and the community of Beaver Dam, Arizona is just northwest of Interstate 15 in the valley of Beaver Dam Wash (fig. 1). Population of both communities is about 300 people. The environment, topography, and geography is typical of the Mohave Desert of Nevada and California. There are about 9 sections of private land in the quadrangle and 5 sections belonging to the state of Arizona. The balance is public land administrated by the U.S. Bureau of Land Management, Arizona Strip District in St. George, Utah. The area supports sparse growth of desert shrubs, mainly creosote bush and cactus. Dense growths of tamerisk (Salt Cedar), cottonwood, and willow trees thrive along the alluvial terraces and banks of the Virgin River. A variety of water loving plants thrive in warm spring waters on the east side of the Virgin River near the Interstate 15 bridge, and in Beaver Dam Wash, northwest corner of the quadrangle.

Arizona↗