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At least 541 records · Page 30Linked to original sources
USGS2014

Simulated effects of increased groundwater withdrawals in the Cave Springs area, Hixson, Tennessee

Concern for future water supplies in Tennessee has grown in recent years as a result of increased awareness of competing needs, the impact of droughts, and the need for more water to support growing populations. The U.S. Geological Survey conducts investigations to improve the knowledge about interactions of geology, climate, humans, and ecosystems with the water cycle, which is critical to understanding and optimizing water availability. The Hixson Utility District in Hamilton County, Tennessee, uses groundwater resources in the Cave Springs area as a water supply, withdrawing water from two well fields located at Cave Springs and Walkers Corner. Historically, Hixson Utility District has withdrawn about 5 million gallons per day (Mgal/d) at the Cave Springs well field and between 2 and 3 Mgal/d at the Walkers Corner well field. To assess the capacity of the groundwater resources in the Cave Springs area to meet future demands, four different scenarios of increased groundwater withdrawals were analyzed using computer model simulations. In the study area, groundwater is present in both regolith and bedrock. Groundwater flow in the regolith occurs as diffuse flow as recharge from precipitation moves through the regolith to discharge to streams and springs or to the underlying bedrock. Most of the bedrock in the study area has low primary porosity and permeability; however, fracturing and dissolution have produced substantial secondary porosity and permeability. Groundwater flow through the bedrock occurs as both diffuse and conduit flow. Recharge to the aquifer is from two distinct sources: direct infiltration of precipitation and losing streams. A major source of recharge to the aquifer that supplies Cave Springs is surface water that is lost from North Chickamauga Creek as it flows from the Cumberland Plateau onto the Newman Limestone. Average annual streamflow loss (groundwater recharge) from this reach of North Chickamauga Creek for the period November 2000 through June 2006 is about 18 cubic feet per second (ft 3 /s). Groundwater leaves the aquifer as either discharge to North Chickamauga Creek, Poe Branch, and Lick Branch; discharge to Chickamauga Lake; spring flow to Cave Springs or Rogers Spring; or withdrawals at the Cave Springs or Walkers Corner well fields. Using computer model simulations, four scenarios of increased groundwater withdrawals were analyzed. Each of these four scenarios are compared to a base-case simulation that uses groundwater withdrawal rates from 2012 of 5.1 Mgal/d from the Cave Springs well field and 2.7 Mgal/d from the Walkers Corner well field. Under scenarios A and B, pumpage is increased at Cave Springs by 2 Mgal/d and 5 Mgal/d, respectively, while pumpage at Walkers Corner remains unchanged. Under scenarios C and D, pumpage is increased at Walkers Corner by 2.6 Mgal/d and 4.5 Mgal/d, respectively, while pumpage at Cave Springs remains unchanged. The effects of the increased withdrawals were analyzed by comparing water budget changes of the groundwater discharges to Chickamauga Lake, North Chickamauga Creek, Cave Springs, Poe Branch, and Lick Branch/Rogers Spring for each of the scenarios and evaluating changes in groundwater levels at the well fields. Under scenarios A and B, the largest change in the water budget occurs for flow to Cave Springs with decreases of 1.9 and 4.7 ft 3 /s, respectively. Similarly, groundwater discharge to North Chickamauga Creek decreases by 1.0 ft 3 /s and 2.6 ft 3 3/s, respectively. Under scenarios C and D, the largest change in the water budget occurs for flow to Chickamauga Lake with decreases of 1.3 ft 3 /s and 2.3 ft 3 /s, respectively. Similarly, groundwater discharge to North Chickamauga Creek decreases by 1.1 ft 3 /s and 2.1 ft 3 /s, respectively. Changes in groundwater levels at the well fields were also analyzed. At the Cave Springs well field, maximum declines in groundwater levels due to additional pumpage are less than 1 foot for all scenarios. Groundwater level changes at the Cave Springs well field are small due to the highly transmissive nature of the aquifer in this location. Maximum groundwater-level declines at Walkers Corner are less than 1 foot for scenarios A and B and about 52 feet and 82 feet for scenarios C and D, respectively. Under scenarios C and D, the regional potentiometric surface shows a large cone of depression centered on the Walkers Corner well field and elongated along geologic strike.

Tennessee↗
USGS2018

Assessment of water resources in areas that affect the habitat of the endangered Hine’s emerald dragonfly in the Lower Des Plaines River Valley, Illinois

Review of previous investigations indicates that potential decreases in groundwater recharge and increased groundwater extraction in the vicinity of the Lower Des Plaines River Valley in Will County, Illinois, may reduce the amount of groundwater flow in the Silurian aquifer in this area. Groundwater discharge from the Silurian aquifer to wetlands in the Lower Des Plaines River Valley plays an important role in sustaining the habitat of the endangered Hine’s emerald dragonfly (Somatochlora hineana). Groundwater modeling performed by previous investigators indicates that increasing the amount of water pumped from the aquifer in support of expanded quarry operations near the Lockport Prairie Nature Preserve has the potential to reduce groundwater discharge to the most productive Hine’s emerald dragonfly habitats in Illinois, potentially degrading the habitat. Model simulations indicate that mitigation procedures designed to artificially enhance groundwater recharge in the vicinity of dragonfly habitats near the Lockport Prairie Nature Preserve are likely to offset the effects of increased pumping. Several areas with smaller, often intermittent populations of Hine’s emerald dragonflies have been identified in other parts of the Lower Des Plaines River Valley and elsewhere in Illinois. Human activities have the potential to produce changes in hydrology and water quality that can threaten all of these habitats.

Illinois↗
USGS2007

Natural and diverted low-flow duration discharges for streams affected by the Waiahole Ditch System, windward O`ahu, Hawai`i

For nearly a century, the Waiahole Ditch System has diverted an average of approximately 27 million gallons per day of water from the wet, northeastern part of windward O`ahu, Hawai`i, to the dry, central part of the island to meet irrigation needs. The system intercepts large amounts of dike-impounded ground water at high altitudes (above approximately 700 to 800 ft) that previously discharged to Waiahole (and its tributaries Waianu and Uwao), Waikane, and Kahana Streams through seeps and springs. Diversion of this ground water has significantly diminished low flows in these streams. Estimates of natural and diverted flows are needed by water managers for (1) setting permanent instream flow standards to protect, enhance, and reestablish beneficial instream uses of water in the diverted streams and (2) allocating the diverted water for instream and offstream uses. Data collected before construction of the Waiahole Ditch System reflect natural (undiverted) flow conditions. Natural low-flow duration discharges for percentiles ranging from 50 to 99 percent were estimated for four sites at altitudes of 75 to 320 feet in Waiahole Stream (and its tributaries Waianu and Uwao Streams), for six sites at altitudes of 10 to 220 feet in Waikane Stream, and for three sites at altitudes of 30 to 80 feet in Kahana Stream. Among the available low-flow estimates along each affected stream, the highest natural Q50 (median) flows on Waiahole (altitude 250 ft), Waianu (altitude 75 ft), Waikane (altitude 75 ft), and Kahana Streams (altitude 30 ft) are 13, 7.0, 5.5, and 22 million gallons per day, respectively. Q50 (median) is just one of five duration percentiles presented in this report to quantify low-flow discharges. All flow-duration estimates were adjusted to a common period of 1960-2004 (called the base period). Natural flow-duration estimates compared favorably with limited pre-ditch streamflow data available for Waiahole and Kahana Streams. Data collected since construction of the ditch system reflect diverted flow conditions, which can be further divided into pre-release and post-release periods - several flow releases to Waiahole, Waianu, and Waikane Streams were initiated between December 1994 and October 2002. Comparison of pre-release to natural flows indicate that the effects of the Waiahole Ditch System diversion are consistently greater at lower low-flow conditions (Q99 to Q90) than at higher low-flow conditions (Q75 to Q50). Results also indicate that the effects of the diversion become less significant as the streams gain additional ground water at lower altitudes. For Waiahole Stream, pre-release flows range from 25 to 28 percent of natural flows at an altitude of 250 feet and from 19 to 20 percent at an altitude of 320 feet. For Waikane Stream, pre-release flows range from 30 to 46 percent of natural flows at an altitude of 10 feet and from 7 to 19 percent at an altitude of 220 feet. For Kahana Stream, pre-release flows range from 65 to 72 percent of natural flows at an altitude of 30 feet and from 58 to 71 percent at an altitude of 80 feet. Estimates of post-release flows were compared with estimates of natural flows to assess how closely current streamflows are to natural conditions. For Waianu Stream, post-release flows at an altitude of 75 feet are 41 to 46 percent lower than corresponding natural flows. For Waikane Stream, post-release flows at an altitude of 75 feet are within 12 percent of the corresponding natural flows. Comparisons of pre-release and post-release flows for Waikane Stream at altitudes of 10 to 220 feet were used to assess downstream changes in flow along the stream reach where flow releases were made. For a particular stream altitude, proportions of pre-release to post-release flows associated with median flows are consistently greater than proportions associated with lower low flows because the relative effect of the flow release is smaller at higher low flows. Similarly, for a particular f

Hawaii↗
USGS2008

Quality of Shallow Ground Water in Three Areas of Unsewered Low-Density Development in Wyoming and Montana, 2001

The quality of shallow ground water underlying unsewered low-density development outside of Sheridan and Lander, Wyo., and Red Lodge, Mont., was evaluated. In 2001, 29 wells (10 each in Sheridan and Lander and 9 in Red Lodge) were installed at or near the water table and sampled for a wide variety of constituents to identify potential effects of human activities on shallow ground-water quality resulting from development on the land surface. All wells were completed in unconfined aquifers in unconsolidated deposits of Quaternary age with shallow water tables (less than 50 feet below land surface). Land use and land cover was mapped in detail within a 500-meter radius surrounding each well, and potential contaminant sources were inventoried within the radii to identify human activities that may affect shallow ground-water quality. This U.S. Geological Survey National Water-Quality Assessment ground-water study was conducted to examine the effects of unsewered low-density development that often surrounds cities and towns of many different sizes in the western United States?a type of development that often is informally referred to as ?exurban? or ?rural ranchette? development. This type of development has both urban and rural characteristics. Residents in these developments typically rely on a private ground-water well for domestic water supply and a private septic system for sanitary waste disposal. Although the quality of shallow ground water generally was suitable for domestic or other uses without treatment, some inorganic constituents were detected infrequently in ground water in the three study areas at concentrations larger than U.S. Environmental Protection Agency drinking-water standards or proposed standards. Natural factors such as geology, aquifer properties, and ground-water recharge rates likely influence most concentrations of these constituents. These inorganic constituents generally occur naturally in the study areas and were more likely to limit suitability of water for drinking or other intended uses rather than any constituents suspected of being introduced as a result of human activities. Effects of human activities associated with low-density development, such as septic systems; fertilizer and pesticide use on pastures, lawns and gardens; manure from horses, cattle, and pets; and increases in road construction and vehicular traffic, were minimal at the time of sampling (2001) but were apparent in the presence of a few types of constituents in shallow ground water. Concentrations of nitrate generally were less than a national background level (1.1 milligrams per liter) assumed to indicate effects from human activities. Total coliform bacteria were detected infrequently (in samples from three wells), and Escherichia coli were not detected in samples from a subset of wells. Trace concentrations of methylene blue active substances (ingredients in laundry detergents) were detected at concentrations slightly greater than laboratory reporting levels in samples from 11 wells, but it is unclear if the detections are indicative of natural sources or possible aquifer contamination from septic-tank effluent. Pesticides were detected in both the Sheridan and Lander, Wyo., study areas. Volatile organic compounds were detected very infrequently in all three study areas. Most pesticides and volatile organic compounds were found in water from a few wells in each study area, and commonly as mixtures. The primary exception to this generalization was the relatively widespread detection of the pesticide prometon at trace levels in the Sheridan and Lander study areas. Concentrations of pesticides and volatile organic compounds generally were small and always were smaller than applicable drinking-water standards. Detections of all constituents indicating possible human effects on shallow ground-water quality were consistent with overlying land use mapped during the study, and potential sources of contamination inventoried du

Scientific Investigations Report↗
USGS2006

Bathymetric map of the north part of Great Salt Lake, Utah, 2006

The U.S. Geological Survey, in cooperation with the Utah Department of Natural Resources, Division of Forestry, Fire, and State Lands, collected bathymetric data for the north part of Great Salt Lake during the spring and early summer of 2006 using a single beam, high-definition fathometer and real-time differential global positioning system. Approximately 5.2 million depth readings were collected along more than 765 miles of survey transects for construction of this map. Sound velocities were obtained in conjunction with the bathymetric data to provide time-of-travel corrections to the depth calculations. Data were processed using commercial hydrographic software and exported into a geographic information system (GIS) software for mapping. Due to the shallow nature of the lake and the limitations of the instrumentation, contours above an altitude of 4,194 feet were digitized from existing USGS 1:24,000 source-scale digital line graph data. The Behrens Trench is approximately located. For additional information on methods used to derive the bathymetric contours for this map, please see Baskin, Robert L., 2006, Calculation of area and volume for the North Part of Great Salt Lake, Utah, U.S. Geological Survey Open-File Report OFR–2006–1359

Utah↗
USGS2016

Bedrock geologic map of the Hartland and North Hartland quadrangles, Windsor County, Vermont, and Sullivan and Grafton Counties, New Hampshire

The bedrock geology of the 7.5-minute Hartland and North Hartland quadrangles, Vermont-New Hampshire, consists of highly deformed and metamorphosed lower Paleozoic metasedimentary, metavolcanic, and metaplutonic rocks of the Bronson Hill anticlinorium (BHA) and the Connecticut Valley trough (CVT). Rocks of the Orfordville anticlinorium on this map occupy the western part of the broader BHA. In the BHA, the Ordovician Ammonoosuc Volcanics and graphitic, sulfidic metapelite of the Partridge Formation are intruded by Ordovician plutonic rocks of the Oliverian Plutonic Suite. The Ordovician rocks are collectively referred to as the Bronson Hill arc. The Ordovician rocks are overlain by the Silurian to Devonian Clough, Fitch, and Littleton Formations. On this map, rocks of the CVT occupy the eastern part of the broader CVT. In the CVT in Vermont, the Silurian to Devonian Shaw Mountain, Waits River, and Gile Mountain Formations form an unconformable autochthonous to parautochthonous cover sequence on the pre-Silurian rocks of the Rowe-Hawley zone above Precambrian basement rocks of the Mount Holly Complex. On this map, however, only the Waits River and Gile Mountain Formations are exposed. Syn- to postmetamorphic rocks include quartz veins and Cretaceous dikes of the White Mountain Igneous Suite. Rocks of the BHA occur in a thrust sheet floored by the Monroe fault, which carried a deformed section of plutonic rocks, Ammonoosuc Volcanics, Partridge Formation, Clough Quartzite, and the Fitch and Littleton Formations. The Monroe thrust sheet placed the BHA rocks over the CVT during an early Acadian F 1 nappe-stage event prior to peak metamorphism at lower amphibolite facies conditions. Upper and lower plate truncations, mylonite, and local mélange characterize the Monroe fault. F 2 doming deformed the Monroe thrust sheet, folded earlier isograds, and created the Meriden antiform and Lebanon dome. Lower greenschist facies (Acadian to Alleghanian) faults such as the Sumner Falls shear zone truncated peak-metamorphic assemblages, isograds, and older F 1 folds and faults. Late-stage F 3 folds show preferred left-lateral rotation sense and are probably related to late dome-stage Alleghanian deformation or motion along lower greenschist facies faults. The youngest deformation is characterized by Mesozoic brittle faulting and spatially associated kink bands along the Ammonoosuc fault zone, followed by subsequent jointing. Currently major economic natural resource activities are related to aggregate quarrying in the Ammonoosuc Volcanics at Twin State Sand and Gravel in Hartford, Vt., and Lebanon Crushed Stone in Lebanon, N.H. This report consists of sheets 1 and 2 as well as an online geographic information systems database that includes contacts of bedrock geologic units, faults, outcrops, structural geologic information, and photographs. Sheet 2 of this report shows three cross sections, a tectonic map, and two brittle features maps that show measured outcrop-scale strike and dip results with summary stereonets and rose diagrams.

New Hampshire, Vermont↗
USGS2024

Global geologic map of Europa

Discovered by Galileo Galilei more than 400 years ago and imaged in detail by the Voyager 2 Galileo spacecraft, Jupiter’s icy moon Europa has been a source of intrigue. A range of science investigations indicate that it contains the key ingredients for habitability, notably energy, chemistry, and liquid water. Europa’s surface is geologically complex and, based on the dearth of impact craters, interpreted to be as young as ~60 Ma. The array of geologic features that characterize the surface include extensive ridged plains, regions of broad disruption termed chaotic terrain, long, quasi-linear ridges that span thousands of kilometers, and bands as much as 60 kilometers wide and that extend 100s of kilometers. These features, along with other geophysical measurements, indicate the presence of a global briny liquid water ocean beneath the ice shell. It was not until the arrival of the Galileo spacecraft in 1995 that the true nature and level of complexity of the surface was revealed. Although image data returned by Galileo provided insight into the structure of a variety of regions, the entire satellite has yet to be observed at a regional scale (less than 250 meters per pixel) and the detailed geologic nature of much of its surface remains a mystery. Establishing the global context of the distribution and timing of Europan geologic units forms a basis to understand regional and local scale processes, serves as a tool for the planning of future missions, and most of all is essential to gaining insight into the potential habitability of this icy world.

Scientific Investigations Map↗
USGS2009

Nutrient Trends in Streams and Rivers of the United States, 1993-2003

Trends in streamflow and concentrations and loads of total phosphorus, total nitrogen, and nitrate were determined for the period from 1993 to 2003 in selected streams and ricers of the United States. Flow-adjusted trends in concentration (the trends that would have occurred in the absence of natural chances in streamflow), non-flow-adjusted trends in concentration (the trends resulting from both natural and human factors), and trends in load (trends in the nutrient mass transported downstream) were determined, and the results were examined spatially to determine whether a consistent pattern of trends occurred across groups of sites at multiple locations. Relations between the trends and changes in nutrient sources and streamflow are examined. See document for complete abstract.

Scientific Investigations Report↗
USGS2021

Geologic assessment of undiscovered oil and gas resources in the Cherokee Platform area of Kansas, Oklahoma, and Missouri

In 2015, the U.S. Geological Survey completed a geology-based assessment to estimate the volumes of undiscovered, technically recoverable petroleum resources in the Cherokee Platform Province area of southeastern Kansas, northeastern Oklahoma, and southwestern Missouri. The U.S. Geological Survey identified four stratigraphic intervals that contain petroleum source rocks: (1) thin shales in the Middle to Upper Ordovician Simpson Group, (2) shales within the Upper Devonian to Lower Mississippian Woodford Shale and stratigraphically equivalent Chattanooga Shale, (3) coals and coal-associated shales and mudstones in the Middle Pennsylvanian (Desmoinesian) Cherokee and Marmaton Groups, and (4) thin marine shales within the Marmaton Group and the Upper Pennsylvanian (Missourian) Kansas City and Lansing Groups. Based on the nature of the petroleum accumulations, the characterization of the compositions and thermal maturity of the organic matter in the rocks, and the compositions of the produced petroleum, the U.S. Geological Survey identified three total petroleum systems (TPS) containing four assessment units (AU): the Paleozoic Composite TPS with the Paleozoic Conventional Assessment Unit (AU), the Woodford/Chattanooga TPS with the Woodford Shale Oil AU and the Woodford Biogenic Gas AU, and the Desmoinesian Coal TPS with the Desmoinesian Coalbed Gas AU. Assessment unit summaries follow 1. Three source rock intervals have contributed geochemically distinct oils to reservoirs within the Paleozoic Conventional AU. These intervals are the Simpson Group; the Woodford and Chattanooga Shales; and the Marmaton, Kansas City, and Lansing Groups. The major petroleum source rocks are the Woodford and Chattanooga Shales. The Paleozoic Conventional AU includes reservoirs that range in age from the Upper Cambrian Arbuckle Group to the lower Permian Chase Group. Most oil production in the province has been from Pennsylvanian sandstone reservoirs. Estimated undiscovered petroleum resources for this AU are a mean of 3 million barrels of oil (MMBO), 140 billion cubic feet of gas (BCFG), and 4 million barrels of natural gas liquids (MMBNGL). 2. The Woodford Shale Oil AU contains undiscovered continuous petroleum resources within the Woodford Shale and Chattanooga Shale. The geologic model for the AU assumes that petroleum resources remain trapped within the shale following petroleum migration. For most of the AU, organic matter within the Woodford Shale and Chattanooga Shale is thermally mature with respect to petroleum generation as shown by vitrinite reflectance values between 0.6 and 1 percent. Petroleum has been produced from the Woodford Shale and Chattanooga Shale. Estimated undiscovered petroleum resources for this AU are means of 460 MMBO, 640 BCFG, and 7 MMBNGL. 3. The Woodford Shale Biogenic Gas AU contains undiscovered continuous petroleum resources in the east-central portion of the Cherokee Platform Province near the Ozark uplift where the Woodford Shale and Chattanooga Shale are at depths of 1,250 ft or shallower. At those depths, methanogenesis and(or) biodegradation of thermogenic natural gases can be found where the shale may be more fractured and more susceptible to groundwater penetrations. The mean assessed volume of undiscovered gas for this assessment unit is 416 BCFG and 1 MMBNGL. 4. The Desmoinesian Coalbed Gas AU contains undiscovered continuous petroleum resources within the Middle Pennsylvanian coals and coal-associated shales and mudstones. The boundaries for the Desmoinesian Coalbed Gas AU are, in part, defined by the extent, depth, and thickness of the coals. Within the Desmoinesian Coalbed Gas AU, a sweet spot area was delineated based on a 10 foot or greater net coal thickness. Gas analytical data show that natural gas produced from the coals has a mixed biogenic and thermogenic origin and that there is significant migration of natural gas into the coals from adjacent conventional sandstone reservoirs. The estimated mean volume of undiscovered gas is 10.0 trillion cubic ft of gas (TCFG), and 23 MMBNGL. For the three continuous (unconventional) assessment units and one conventional assessment unit in the Cherokee Platform Province, total mean volumes of undiscovered petroleum resources are estimated to be 463 MMBO, 11.2 TCFG and 35 MMBNGL.

Kansas, Missouri, Oklahoma↗
USGS2026

Flood-inundation extents and hydraulic characteristics of Carson Slough, Ash Meadows National Wildlife Refuge, Nevada

Mud Lake Dam, a rock and earth embankment structure, crosses an ephemeral stream that once flowed naturally into Carson Slough, the largest wetland complex in southern Nevada and a critical habitat for several threatened and endangered species. The dam was breached in the 1990s, rerouting stormwater into a new channel. The Bureau of Land Management and U.S. Fish and Wildlife Service are considering possible dam modifications to establish streamflow back to the natural channel. The U.S. Geological Survey, in collaboration with the Bureau of Land Management and U.S. Fish and Wildlife Service, developed hydrologic and hydraulic models to assess how peak-flow breach expansion and possible dam modifications could affect flooding in Carson Slough. A precipitation-runoff model was developed to estimate 6-hour and 24-hour flood streamflows for 10-, 25-, 50-, and 100-year floods, which were used as inputs to a hydraulic model simulating three scenarios: 2023 conditions, peak-flow breach expansion, and possible dam modifications. Model outputs included flood-inundation extents and hydraulic characteristics such as water depth and velocity. Under 2023 conditions, streamflow enters the dam breach and follows the breach channel to the west into Carson Slough, inundating Soda Spring. Only under the highest flood scenario (24-hour duration, 100-year rainfall recurrence interval) did streamflow also enter the natural channel directly downstream from the dam. Under possible dam modification conditions, streamflow remained solely in the natural channel and flowed southwest into Carson Slough. Under peak-flow breach expansion, streamflow entered the breach and natural channels and into Carson Slough. Compared to 2023 conditions, the total inundated extent for peak-flow breach expansion increased by 7–11 percent, whereas possible dam modification conditions decreased by 4–7 percent. Inundation extents remained largely similar throughout most of the study area, and the primary exception was in the 1-mile segment directly downstream from the dam.

Nevada↗
USGS2006

Water-Table Levels and Gradients, Nevada, 1947-2004

In 1999, the U.S. Environmental Protection Agency began a program to protect the quality of ground water in areas other than ground-water protection areas. These other sensitive ground water areas (OSGWA) are areas that are not currently, but could eventually be, used as a source of drinking water. The OSGWA program specifically addresses existing wells that are used for underground injection of motor-vehicle waste. To help determine whether a well is in an OSGWA, the Nevada Division of Environmental Protection needs statewide information on depth to water and the water table, which partly control the susceptibility of ground water to contamination and contaminant transport. This report describes a study that used available maps and data to create statewide maps of water-table and depth-to-water contours and surfaces, assessed temporal changes in water-table levels, and characterized water-table gradients in selected areas of Nevada. A literature search of published water-table and depth-to-water contours produced maps of varying detail and scope in 104 reports published from 1948 to 2004. Where multiple maps covered the same area, criteria were used to select the most recent, detailed maps that covered the largest area and had plotted control points. These selection criteria resulted in water-table and depth-to-water contours that are based on data collected from 1947 to 2004 being selected from 39 reports. If not already available digitally, contours and control points were digitized from selected maps, entered into a geographic information system, and combined to make a statewide map of water-table contours. Water-table surfaces were made by using inverse distance weighting to estimate the water table between contours and then gridding the estimates. Depth-to-water surfaces were made by subtracting the water-table altitude from the land-surface altitude. Water-table and depth-to-water surfaces were made for only 21 percent of Nevada because of a lack of information for 49 of 232 basins and for most consolidated-rock hydrogeologic units. Depth to water is commonly less than 50 feet beneath valley floors, 50 to 500 feet beneath alluvial fans, and more than 500 feet in some areas such as north-central and southern Nevada. In areas without water-table information, greasewood and mapped ground-water discharge areas are good indicators of depth to water less than 100 feet. The average difference between measured depth to water and depth to water estimated from surfaces was 90 feet. More recent and detailed information may be needed than that presented in this report to evaluate a specific site. Temporal changes in water-table levels were evaluated for 1,981 wells with 10 or more years between the first depth-to-water measurement and last measurement made since 1990. The greatest increases in depth to water occurred where the first measurement was less than 200 feet, where the time between first and last measurements was 40 years or less, and for wells between 100 and 600 feet deep. These characteristics describe production wells where ground water is fairly shallow in recently developing areas such as the Las Vegas and Reno metropolitan areas. In basins with little pumping, 90 percent of the changes during the past 100 years are within ?20 feet, which is about the natural variation in the water table due to changes in the climate and recharge. Gradients in unconsolidated sediments of the Great Basin are generally steep near mountain fronts, shallow beneath valley floors, and depend on variables such as the horizontal hydraulic conductivity of adjacent consolidated rocks and recharge. Gradients beneath alluvial fans and valley floors at 58 sites were correlated with selected variables to identify those variables that are statistically related. Water-table measurements at three sites were used to characterize the water table between the valley floor and consolidated rock. Water-table gradients beneath alluvial fan

Scientific Investigations Report↗
USGS2009

U.S. Geological Survey Groundwater Modeling Software: Making Sense of a Complex Natural Resource

Computer models of groundwater systems simulate the flow of groundwater, including water levels, and the transport of chemical constituents and thermal energy. Groundwater models afford hydrologists a framework on which to organize their knowledge and understanding of groundwater systems, and they provide insights water-resources managers need to plan effectively for future water demands. Building on decades of experience, the U.S. Geological Survey (USGS) continues to lead in the development and application of computer software that allows groundwater models to address scientific and management questions of increasing complexity.

Fact Sheet↗
USGS1969

The Geologic Story of the Uinta Mountains

The opening of the West after the Civil War greatly stimulated early geologic exploration west of the 100th Meridian. One of the areas first studied, the Uinta Mountains region, gained wide attention as a result of the explorations of three Territorial Surveys, one headed by John Wesley Powell, one by Clarence King, and one by Ferdinand V. Hayden. Completion of the Union Pacific Railroad across southern Wyoming 100 years ago, in 1869, materially assisted geologic exploration, and the railheads at Green River and Rock Springs greatly simplified the outfitting of expeditions into the mountains. The overlap of the Powell, King, and Hayden surveys in the Uinta Mountains led to efforts that were less concerted than competitive and not without acrimony. Many parts of the area were seen by all three parties at almost the same time. Duplication was inevitable, of course, but all three surveys contributed vast quantities of new knowledge to the storehouse of geology, and many now-basic concepts arose from their observations. Powell's area of interest extended mainly southward from the Uinta Mountains to the Grand Canyon, including the boundless plateaus and canyons of southern Utah and northern Arizona. King's survey extended eastward from the High Sierra in California to Cheyenne, Wyoming, and encompassed a swath of country more than 100 miles wide. Hayden's explorations covered an immense region of mountains and basins from Yellowstone Park in Wyoming southeast throughout most of Colorado. Powell first entered the Uinta Mountains in the fall of 1868, having traveled north around the east end of the range from the White River country to Green River, Wyoming, then south over a circuitous route to Flaming Gorge and Browns Park, and finally back to the White River, where he spent the winter. In 1869, after reexamining much of the area visited the previous season, Powell embarked on his famous 'first boat trip' down the Green and Colorado Rivers. This trip was more exploratory than scientific; his second, more scientific trip was made 2 years later. Powell revisited the Uinta Mountains in 1874 and 1875 to complete the studies begun 6 years earlier. His classic 'Report on the Geology of the Eastern Portion of the Uinta Mountains and a Region of Country Adjacent Thereto' was published in 1876. King's survey?officially 'The United States Geological Exploration of the Fortieth Parallel'?is better known simply as the '40th Parallel Survey.' King began working eastward from California in 1867. The Uinta Mountains region, however, was mapped by S. F. Emmons, under the supervision of King, in the summers of 1869 and 1871. Emmons' work was monumental, and although he emphasized in his letter of transmittal to King the exploratory nature of the work?as the formal title of the report indicates?his maps, descriptions, and conclusions reflect a comprehensive understanding of the country and its rocks. The 40th Parallel report contains the best, most complete early descriptions of the Uinta Mountains. It, indeed, is a treasurechest of information and a landmark contribution to the emerging science of geology. Hayden visited the Uinta Mountains in 1870, descending the valley of Henrys Fork to Flaming Gorge in the fall after having earlier examined the higher part of the range to the west. Most of Hayden's observations were cursory, and he repeatedly expressed regret at having insufficient time for more detailed studies. In reference to the area between Clay Basin and Browns Park, he remarked (Hayden, 1871, p. 67) somewhat dryly that 'the geology of this portion of the Uinta range is very complicated and interesting. To have solved the problem to my entire satisfaction would have required a week or two.' Eighty-odd years later I spent several months there?looking at the same rocks. Powell was perhaps more creative?more intuitive?than either King or Hayden, and his breadth of interest in the fields of geology, physiography, ethnology, an

Bulletin↗
USGS2005

Stream-sediment geochemistry in mining-impacted streams: Sediment mobilized by floods in the Coeur D'Alene-Spokane River system, Idaho and Washington

Environmental problems associated with the dispersion of metal-enriched sediment into the Coeur d'Alene-Spokane River system downstream from the Coeur d'Alene Mining District in northern Idaho have been a cause of litigation since 1903, 18 years after the initiation of mining for lead, zinc, and silver. Although direct dumping of waste materials into the river by active mining operations stopped in 1968, metal-enriched sediment continues to be mobilized during times of high runoff and deposited on valley flood plains and in Coeur d'Alene Lake (Horowitz and others, 1993). To gauge the geographic and temporal variations in the metal contents of flood sediment and to provide constraints on the sources and processes responsible for those variations, we collected samples of suspended sediment and overbank deposits during and after four high-flow events in 1995, 1996, and 1997 in the Coeur d'Alene-Spokane River system with estimated recurrence intervals ranging from 2 to 100 years. Suspended sediment enriched in lead, zinc, silver, antimony, arsenic, cadmium, and copper was detected over a distance of more than 130 mi (the downstream extent of sampling) downstream of the mining district. Strong correlations of all these elements in suspended sediment with each other and with iron and manganese are apparent when samples are grouped by reach (tributaries to the South Fork of the Coeur d'Alene River, the South Fork of the Coeur d'Alene River, the main stem of the Coeur d'Alene River, and the Spokane River). Elemental correlations with iron and manganese, along with observations by scanning electron microscopy, indicate that most of the trace metals are associated with Fe and Mn oxyhydroxide compounds. Changes in elemental correlations by reach suggest that the sources of metal-enriched sediment change along the length of the drainage. Metal contents of suspended sediment generally increase through the mining district along the South Fork of the Coeur d'Alene River, decrease below the confluence of the North and South Forks, and then increase again downstream of the gradient flattening below Cataldo. Metal contents of suspended sediment in the Spokane River below Coeur d'Alene Lake were comparable to those of suspended sediment in the main stem of the Coeur d'Alene River above the lake during the 1997 spring runoff, but with somewhat higher Zn contents. Daily suspended-sediment loads were about 100 times larger in the 1996 flood (50-100-year recurrence interval) than in the smaller 1997 floods (2-5-year recurrence intervals). Significant differences in metal ratios and contents are also apparent between the two flood types. The predominant source of suspended sediment in the larger 1996 flood was previously deposited, metal-enriched flood-plain sediment, identified by its Zn/Pb ratio less than 1. Suspended sediment in the smaller 1997 floods had metal ratios distinct from those of the flood-plain deposits and was primarily derived from metal-enriched sediment stored within the stream channel, identified by a Zn/Pb ratio greater than 1. Sediment deposited during overbank flooding on the immediate streambank or natural levee of the river typically consists of sandy material with metal ratios and contents similar to those of the sandy streambed sediment in the adjacent river reach. Samples of overbank deposits in backlevee marshes collected after the 1996 flood have metal ratios similar to those of peak-flow suspended sediment in the same river reach, but generally lower metal contents.

Idaho, Washington↗
USGS2006

Land-cover trends in the Mojave basin and range ecoregion

The U.S. Geological Survey's Land-Cover Trends Project aims to estimate the rates of contemporary land-cover change within the conterminous United States between 1972 and 2000. A random sampling approach was used to select a representative sample of 10-km by 10-km sample blocks and to estimate change within +/- 1 percent at an 85-percent confidence interval. Landsat Multispectral Scanner, Thematic Mapper, and Enhanced Thematic Mapper Plus data were used, and each 60-m pixel was assigned to one of 11 distinct land-cover classes based upon a modified Anderson classification system. Upon completion of land-cover change mapping for five dates, land-cover change statistics were generated and analyzed. This paper presents estimates for the Mojave Basin and Range ecoregion located in the southwestern United States. Our research suggests land-cover change within the Mojave to be relatively rare and highly localized. The primary shift in land cover is unidirectional, with natural desert grass/shrubland being converted to development. We estimate that more than 1,300 km2 have been converted since 1973 and that the conversion is being largely driven by economic and recreational opportunities provided by the Mojave ecoregion. The time interval with the highest rate of change was 1986 to 1992, in which the rate was 0.21 percent (321.9 km2) per year total change.

Scientific Investigations Report↗
USGS2011

Simulation of streamflow in the Pleasant, Narraguagus, Sheepscot, and Royal Rivers, Maine, using watershed models

The U.S. Geological Survey (USGS) began a study in 2008 to investigate anticipated changes in summer streamflows and stream temperatures in four coastal Maine river basins and the potential effects of those changes on populations of endangered Atlantic salmon. To achieve this purpose, it was necessary to characterize the quantity and timing of streamflow in these rivers by developing and evaluating a distributed-parameter watershed model for a part of each river basin by using the USGS Precipitation-Runoff Modeling System (PRMS). The GIS (geographic information system) Weasel, a USGS software application, was used to delineate the four study basins and their many subbasins, and to derive parameters for their geographic features. The models were calibrated using a four-step optimization procedure in which model output was evaluated against four datasets for calibrating solar radiation, potential evapotranspiration, annual and seasonal water balances, and daily streamflows. The calibration procedure involved thousands of model runs that used the USGS software application Luca (Let us calibrate). Luca uses the Shuffled Complex Evolution (SCE) global search algorithm to calibrate the model parameters. The calibrated watershed models performed satisfactorily, in that Nash-Sutcliffe efficiency (NSE) statistic values for the calibration periods ranged from 0.59 to 0.75 (on a scale of negative infinity to 1) and NSE statistic values for the evaluation periods ranged from 0.55 to 0.73. The calibrated watershed models simulate daily streamflow at many locations in each study basin. These models enable natural resources managers to characterize the timing and amount of streamflow in order to support a variety of water-resources efforts including water-quality calculations, assessments of water use, modeling of population dynamics and migration of Atlantic salmon, modeling and assessment of habitat, and simulation of anticipated changes to streamflow and water temperature resulting from changes forecast for air temperature and precipitation.

Scientific Investigations Report↗
USGS2004

Potentiometric surfaces in the Cockfield and Wilcox aquifers of southern and northeastern Arkansas, 2003

This report presents the results of water-level measurements made at wells in the Cockfield Formation and Wilcox Group of southern and northeastern Arkansas during 2003, and the water levels are displayed in potentiometric-surface maps and hydrographs. During March and April 2003, the water level was measured at 55 wells completed in the Cockfield aquifer, 13 wells completed in the Wilcox aquifer of southern Arkansas, and 43 wells completed in the Wilcox aquifer of northeastern Arkansas. The Cockfield Formation generally consists of discontinuous sand units interbedded with silt, clay, and lignite in southeastern Arkansas. Sand beds near the base of the Cockfield Formation constitute most of the Cockfield aquifer. Withdrawals from the Cockfield aquifer in the study area during 2000 totaled about 9 million gallons per day. The potentiometric surface of the Cockfield aquifer constructed from the 2003 water levels shows that regional direction of ground-water flow generally is towards the east and southeast, away from the outcrop, except in areas of intense ground-water withdrawals. Some local ground-water flow in the outcrop area is toward rivers that have eroded into the Cockfield Formation and deposited alluvium in south Bradley and Calhoun Counties (Ouachita River), and in north Dallas County (Saline River). An evaluation of 20 wells with water-level data from 1983 to 2003 shows that water levels in 15 wells have declined at a rate of -0.04 to -0.97 feet per year, and water levels in 5 wells have risen at a rate of 0.07 to 0.32 feet per year. An evaluation of the same 20 wells from 2000 to 2003 shows that water levels have declined in only 8 wells, and water levels have risen in 12 wells. The Wilcox Group is distributed throughout most of southern and eastern Arkansas. There are two study areas in southern and northeastern Arkansas. The Wilcox Group of the southern study area consists of interbedded clay, sandy clay, sand, and lignite. Thin discontinuous sand units constitute the Wilcox aquifer in the southern study area. Withdrawals from the aquifer in the southern study area were about 1 million gallons per day during 2000. The potentiometric surface of the Wilcox aquifer in the southern study area shows that regional ground-water flow generally is south and east, except in Clark County where flow is towards the Ouachita River. The Wilcox Group in the northeastern study area consists of thin interbedded lignitic sand and clays. A sand bed of about 200 feet thick in the middle to lower part of the Wilcox Group constitutes the major producing unit of the Wilcox aquifer in the northeastern study area. Withdrawals from the aquifer in the northeastern study area were about 23 million gallons per day during 2000. The potentiometric surface of the Wilcox aquifer in the northeastern study area shows that ground-water flow generally is south and east, except where ground-water withdrawals may have altered the natural direction of flow near the centers of pumping at Paragould and West Memphis. An evaluation of 27 wells with water-level data from 1983 to 2003 in the northeastern study area shows that water levels in all 27 wells have been declining at a rate of -0.17 to -1.73 feet per year. An evaluation of the same 27 wells from 2000 to 2003 shows that water levels in 18 wells have risen and in 9 wells have declined.

Scientific Investigations Report↗
USGS2016

Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River—A synthesis of science, 2005 to 2012

This report is intended to synthesize the state of the scientific understanding of pallid sturgeon ecological requirements to provide recommendations for future science directions and context for Missouri River restoration and management decisions. Recruitment of pallid sturgeon has been low to non-existent throughout its range. Emerging understanding of the genetic structure of pallid sturgeon populations sets a broad framework for species and river management decisions, including decisions about managing the future genetic diversity of the species, but also decisions about where and what type of river restoration actions will be effective for subpopulations of this highly migratory species. Adult pallid sturgeon may migrate hundreds of kilometers (km) to spawn and their progeny may disperse even greater distances downstream as drifting free embryos. As a result of their complex life history pallid sturgeon naturally exploit a wide range of habitats during their life cycles. The construction of dams and reservoirs has fragmented habitats and may have shifted Missouri River subpopulations downstream. Research has not identified one primary biological or ecological constraint that appears to limit populations of the pallid sturgeon. With the present (2013) state of knowledge many life stages and life-stage transitions cannot be ruled out as contributing to recruitment failure. Biological opinions in 2000 (and amended in 2003) presented the dominant hypotheses for recruitment failure that existed at that time. Emphasis was on the role of the flow regime, specifically spring flow pulses (“spring rises”), to condition spawning substrate and cue reproductive aggregations and migrations, and on low flows and additional slow, shallow-water area to serve as rearing habitat for age-0 to juvenile pallid sturgeon. Studies on spawning habitat dynamics have documented that habitat patches selected for spawning by fish in the Lower Missouri River (Missouri River downstream from Gavins Point Dam to the confluence with the Mississippi River) are dominantly on outside, revetted bends in the deepest, fastest, and most turbulent water. Studies in more natural habitat on the Yellowstone River have documented spawning in convergent flow in the middle of the channel on discrete patches of gravel within a sand-dominated channel, an arrangement that may be more effective in attracting aggregations of reproductive fish compared to the nearly continuous revetment on the Lower Missouri River. Pallid sturgeon spawn in the spring and early summer during periods of increasing day length. Water temperature consistently exerts a threshold effect for spawning at 16–18 °C. In addition, the role of water temperature is indicated by pauses and reversals in upstream migrations that have been associated with cold weather fronts that create a transient decrease in water temperature. From 2005 to 2012 on the Lower Missouri River, no obvious relations between flow pulses and fish movements and spawning behaviors have been apparent. However, pallid sturgeon tracking at the Upper Missouri–Yellowstone confluence indicates that in most years, most telemetered pallid sturgeon migrate out of the Missouri River and into the Yellowstone River in the June–July timeframe in association with the spring pulse. This pattern was disrupted in 2011 when a high flow pulse with warm temperatures and high turbidity emanated from the Milk River, followed by record releases from Fort Peck Dam, and 36–39 percent of the telemetered population migrated up the Upper Missouri. This result supports the hypothesis that sufficiently large flow pulses may trigger migration and aggregation but it is not clear that functional pulses are within reservoir management authorities. Notably, a pallid sturgeon free embryo was captured on the Upper Missouri River in 2011 and another single, genetically confirmed embryo was captured on the Yellowstone River in 2012. Research on free-embryo drift has indicated the potential for hundreds of miles of downstream dispersal. Lack of distance to accommodate the extended downstream dispersal period of free embryos on the Upper Missouri and Yellowstone Rivers is the predominant hypothesis for recruitment failure in the upper basin. Long drift distances in the Lower Missouri River may be responsible for shifting Lower Missouri River sub-populations further into the Middle Mississippi River. Physical understanding of drift processes indicates that mean velocities could be slowed through decreased discharges or increased channel hydraulic radius (width and topographic diversity) to reduce free-embryo dispersal distances. In addition, the probability that free embryos are transported into and retained in channel-margin habitats is theoretically amenable to channel re-engineering that would increase cross-channel secondary currents in bends or channel expansions. Considerable uncertainty persists, however, about whether extended drift of Lower Missouri River larvae is responsible for recruitment failure. If drift distance is limiting, it is important to discern whether it would be advisable to retain larvae within the Missouri River, and where along the river restoration projects should be placed to optimize survival and growth of age-0 and juvenile sturgeon. Longitudinal differences in female pallid sturgeon fecundity lend support to the hypothesis that recruitment failure may be due, in part, to fish having insufficient nutrition to produce the numbers of gametes needed for the population to grow, perhaps because of simultaneous declines in prey-fish populations and their habitats. Establishing a chain of causality from habitat decline, to prey-fish populations, to sturgeon diets, to sturgeon fecundity, and to pallid sturgeon population growth presents a considerable scientific challenge. In addition to the dominant hypotheses relating pallid sturgeon populations to changes in flow regime and channel morphology, other factors have been identified that might be sources of stress and contribute to recruitment failure. Among these are water quality and contaminants. Ambient water-quality monitoring on the Missouri River has demonstrated summer episodes when dissolved oxygen dips below 5 milligrams per liter, a threshold that may be stressful especially to age-0 and juvenile sturgeon. Documented cases of intersex in shovelnose and pallid sturgeon indicate that agricultural and municipal sources of endocrine disrupting chemicals also may have a role in pallid sturgeon recruitment failure. Scientific understanding of the ecological requirements of pallid sturgeon has increased almost exponentially in the last two decades, and efforts are now turning from understanding fundamental biology of the species to quantifying how population dynamics relate to potential management actions. Progress in developing the science needed to inform management actions on the Missouri River may benefit from continuation of monitoring of reproductive cycles, reproductive movements, growth, and survival of telemetry tagged adults, increased emphasis on focused, complementary field and laboratory studies of factors influencing early life history, implementation of studies to resolve the role of food limitations in growth, survival, and reproductive condition, and implementation of studies designed specifically to parameterize models linking management to populations.

Missouri River↗