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At least 199 records · Page 11Linked to original sources
USGS2015

Hydrologic data for the Walker River Basin, Nevada and California, water years 2010–14

Walker Lake is a threatened and federally protected desert terminal lake in western Nevada. To help protect the desert terminal lake and the surrounding watershed, the Bureau of Reclamation and U.S. Geological Survey have been studying the hydrology of the Walker River Basin in Nevada and California since 2004. Hydrologic data collected for this study during water years 2010 through 2014 included groundwater levels, surface-water discharge, water chemistry, and meteorological data. Groundwater levels were measured in wells, and surface-water discharge was measured in streams, canals, and ditches. Water samples for chemical analyses were collected from wells, streams, springs, and Walker Lake. Chemical analyses included determining physical properties; the concentrations of major ions, nutrients, trace metals, dissolved gases, and radionuclides; and ratios of the stable isotopes of hydrogen and oxygen. Walker Lake water properties and meteorological parameters were monitored from a floating platform on the lake. Data collection methods followed established U.S. Geological Survey guidelines, and all data are stored in the National Water Information System database. All of the data are presented in this report and accessible on the internet, except multiple-depth Walker Lake water-chemistry data, which are available only in this report.

California, Nevada↗
USGS1985

Hydrogeologic data from a test well in east-central Duval County, Florida

A 2,112-foot test well was drilled in east-central Duval County, Florida, to obtain geologic, hydrologic, and water chemistry data. Drill cuttings and water samples were collected, and water-level measurements and lithologic and geophysical logs were made. Deposits to a depth of 575 feet consist of sand, clayey sand, phosphatic sandy clay, coquina, sandy limestone, and dolostone. Below 575 feet, the deposits consist of fragmented and granular limestone, dolomitic limestone, and massive to finely crystalline dolostone, which comprise the Floridan aquifer system in the area. Water levels were measured near or at the bottom of the drill hole through the drill stem and in the annular space between the drilled hole and drill stem at the well head as drilling progressed from 770 to 2,112 feet in depth. Water levels measured through the drill stem ranged from 1.17 feet above land surface at a depth of 2,107 feet to 15.0 feet above land surface at a depth of 1,574 feet. Water levels measured in the annular space ranged from 7.5 feet above land surface at a depth of 770 feet to 14.9 feet at various depths from 1,574 to 1,721 feet. Chloride concentrations of water sampled through the drill stem from a depth of 711 to 1 ,616 feet ranged from 22 to 150 milligrams per liter at 1,648 feet. Chloride concentrations then ranged from 345 to about 800 milligrams per liter to a depth of 2,071 feet and then increased to a maximum of 5,450 milligrams per liter at 2,107 feet. (USGS)

Open-File Report↗
USGS2016

Normal streamflows and water levels continue—Summary of hydrologic conditions in Georgia, 2014

The U.S. Geological Survey (USGS) South Atlantic Water Science Center (SAWSC) Georgia office, in cooperation with local, State, and other Federal agencies, maintains a long-term hydrologic monitoring network of more than 350 real-time, continuous-record, streamflow-gaging stations (streamgages). The network includes 14 real-time lake-level monitoring stations, 72 real-time surface-water-quality monitors, and several water-quality sampling programs. Additionally, the SAWSC Georgia office operates more than 204 groundwater monitoring wells, 39 of which are real-time. The wide-ranging coverage of streamflow, reservoir, and groundwater monitoring sites allows for a comprehensive view of hydrologic conditions across the State. One of the many benefits this monitoring network provides is a spatially distributed overview of the hydrologic conditions of creeks, rivers, reservoirs, and aquifers in Georgia. Streamflow and groundwater data are verified throughout the year by USGS hydrographers and made available to water-resource managers, recreationists, and Federal, State, and local agencies. Hydrologic conditions are determined by comparing the statistical analyses of data collected during the current water year to historical data. Changing hydrologic conditions underscore the need for accurate, timely data to allow informed decisions about the management and conservation of Georgia’s water resources for agricultural, recreational, ecological, and water-supply needs and in protecting life and property.

Georgia↗
USGS2012

Monograph for using paleoflood data in Water Resources Applications

The Environmental and Water Resources Institute (EWRI) Technical Committee on Surface Water Hydrology is sponsoring a Task Committee on Paleoflood Hydrology to prepare a monograph entitled, "Use of Paleoflood and Historical Data in Water Resources Applications." This paper introduces the subject of paleoflood hydrology and discusses the topics, which are expected to be included in the monograph. The procedure for preparing and reviewing the monograph will also be discussed. The paleoflood hydrology monograph will include a discussion of types of hydrologic and paleoflood data, paleostage indicators, flood chronology, modeling methods, interpretation issues, water resources applications and case studies, and research needs. Paleoflood data collection and analysis techniques will be presented, and various applications in water-resources investigations will be provided. An overview of several flood frequency analysis approaches, which consider historical and paleoflood data along with systematic streamflow records, will be presented. The monograph is scheduled for completion and publication in 2001. Copyright ASCE 2004.

Conference Paper↗
USGS1995

Water-quality and hydrologic conditions at a site of ground-water contamination by volatile organic compounds, South Grafton, Massachusetts, September and October 1994

Ground-water quality and hydrologic data were collected at a site contaminated by volatile organic compounds (VOCs) in South Grafton, Massachusetts, during September and October 1994. The VOCs have formed a plume of contaminated ground water at an abandoned textile mill adjacent to the Blackstone River. Concentrations of total VOCs in the plume ranged from less than 1 to more than 40,000 micrograms per liter. Trichloroethylene (TCE) was the primary chlorinated contaminant, comprising as much as 98 percent of the total VOCs. The highest concentration, 43,000 micrograms per liter, was higher than any previously measured concentration at the site; however, the maximum extent and distribution of concentrations in the VOC plume in September 1994 was similar to that found in July 1993 and in earlier rounds of sampling. In addition to TCE, 1,2-dichloroethene (1,2-DCE) and vinyl chloride were detected at most sites. Spatial and temporal changes in concentrations of TCE, 1,2-DCE, and vinyl chloride are consistent with the hypothesis that TCE biodegradation was the source of 1,2-DCE and vinyl chloride. Ground water at the site contained low to moderately high concentrations of dissolved solids (44 to 406 milligrams per liter), had a moderately high specific conductance (155 to 670 microsiemens per centimeter at 25 degrees Celsius), and was slightly acidic (pH=5.9 to 7.0). Concentrations of the major ions-calcium, sodium, chloride, and sulfate-were not related to VOC concentrations. Dissolved-oxygen concentrations were low (0 to 2 milligrams per liter) throughout most of the aquifer. Distribution of nitrogen species, iron, and manganese indicates that zones of varying oxidation-reduction potential were present in the aquifer. Concentrations of trace metals other than iron or manganese, including arsenic, cadmium, chromium, and copper, generally were less than analytical detection limits. Stream stage in the Blackstone River at the site during September and October 1994 fluctuated by about 1 to 2 feet within 24-hour periods. These rapid fluctuations resulted from sudden release of impounded water at a hydroelectric-generating facility downstream from the site. In addition to the daily fluctuations, rapid small changes in stream stage also occurred that were related to storms. Fluctuations in ground-water levels in four observation wells at the site were similar in amplitude and timing to the rapid fluctuations in stream stage; the daily fluctuations of ground-water levels were greatest in an observation well within 100 feet of the river and least in an observation well about 300 feet from the river. Because ground- water levels at the study site seem to be affected by fluctuations in stage of the Blackstone River, transport of the VOC plume in ground water also is likely to be affected by the fluctuations in stage.

Open-File Report↗
USGS2021

Seasonal periphyton response to low-level nutrient exposure in a least disturbed mountain stream, the Buffalo River, Arkansas

Like most streams located in the Ozark Plateaus, the Buffalo River in Arkansas generally has excellent water quality. Water-quality conditions in Big Creek, however, a major tributary of the middle Buffalo River, have been less favorable than that of other Buffalo River tributaries. Concerns regarding the influence of water quality in Big Creek on the Buffalo River magnified in 2013 when a large confined animal feeding operation (CAFO) began operating in the watershed. In response to these concerns, the U.S. Geological Survey compared monthly nutrient concentrations and seasonal periphyton assemblage metrics of a site on Big Creek downstream of the CAFO, two Buffalo River control sites upstream of the confluence with Big Creek, and three Buffalo River test sites downstream of the confluence with Big Creek. In addition to identifying potential nutrient patterns and periphyton responses along a low-level nutrient exposure gradient, the study determined how nutrient contributions from Big Creek (and the CAFO) are affecting ecological conditions and consequent ecosystem services in the Buffalo River. Nutrient and periphyton data exhibited more temporal than spatial variability. Nutrient concentrations were generally highest of all sites at the Big Creek site. Concentrations at the five sites on the Buffalo River were typically low (near laboratory reporting limits), and concentrations at the three test sites rarely exceeded those of the two control sites. An index developed with three ecologically relevant periphyton metrics (oligotrophic taxa and Homoeothrix percent relative abundance and mesotrophic diatoms percent taxa richness) suggested that nutrient uptake at sites downstream of the Big Creek-Buffalo River confluence resulted in subtle shifts in downstream periphyton assemblages. The periphyton index of biological integrity at control sites was slightly and generally more favorable compared to test sites. Even so, when periphyton data were considered in conjunction with both hydrology and water-quality data, the negative consequences of antecedent high flows and associated scouring exceeded the potential positive effects that low-level nutrients had on algal productivity. These findings emphasize the importance of comparing biological and chemical data across extended temporal scales, particularly when working with low-level nutrient gradients.

Arkansas↗
USGS2023

Predevelopment water levels, groundwater recharge, and selected hydrologic properties of aquifer materials, Hinkley and Water Valleys, California

Hydrologic and geophysical data were collected to support updates to an existing groundwater-flow model of Hinkley Valley, California, in the Mojave Desert about 80 miles northeast of Los Angeles, California. These data provide information on predevelopment (pre-1930) water levels, groundwater recharge, and selected hydrologic properties of aquifer materials. A predevelopment groundwater-level map, drawn using water-level measurements from 48 wells collected as early as 1918, showed groundwater movement from recharge areas along the Mojave River to evaporative discharge areas near the margin of Harper (dry) Lake in Water Valley. During predevelopment conditions, depth to water ranged from near land surface along the Mojave River to above land surface near Harper (dry) Lake, consistent with flowing wells in Water Valley at that time. Depths to water in much of Hinkley Valley downgradient from the Lockhart fault were less than 20 feet below land surface. By 2017, water-level declines as a result of agricultural pumping, were as much as 60 feet near the Hinkley compressor station. Areal recharge from infiltration of precipitation on the valley floor is negligible. Average annual recharge as infiltration of runoff from upland drainages to Hinkley and Water Valleys averages 64.7 acre-feet per year. In most years recharge does not occur; in years when it occurs, recharge to Hinkley Valley is typically about 296 acre-feet. In contrast, average recharge as infiltration of streamflow from the Mojave River from 1931 to 2015 was between 13,400 and 17,100 acre-feet per year; in some years recharge from the Mojave River exceeded 100,000 acre-ft. Estimates of predevelopment groundwater movement through Hinkley Gap and groundwater discharge to Harper (dry) Lake ranged from 570 to 1,900 and 820 to 2,460 acre-feet per year, respectively; at the time of this study in 2017, groundwater movement through Hinkley Gap was estimated to be about 83 acre-feet per year. Hydraulic-conductivity values estimated from slug-test data for 95 monitoring wells ranged from less than 0.1 to 680 feet per day (ft/d); values generally decreased with depth. Median hydraulic-conductivity values calculated from nuclear magnetic resonance (NMR) data for Mojave River alluvium and near-shore lake deposits were 73 and 11 ft/d, respectively; median hydraulic-conductivity values for locally derived alluvium and weathered bedrock were 6 and 2 ft/d, respectively. Hydraulic-conductivity values, estimated from NMR data for formerly saturated deposits overlying the 2017 water table, were as high as 300 ft/d near the Hinkley compressor station. Downgradient from the Hinkley compressor station, formerly saturated deposits had hydraulic-conductivity values of about 150 ft/d, which were higher than values in saturated material. Coarse-textured, permeable material in formerly saturated deposits above the 2017 water table may have allowed groundwater, released from the Hinkley compressor station that may have contained Cr(VI), to move rapidly downgradient. The Lockhart fault is an impediment to groundwater flow within Hinkley Valley. Groundwater-flow directions from horizontal point-velocity probe data were deflected to the west on the upgradient side of the fault compared to the nominal direction of groundwater flow estimated from water-level data. Younger groundwater was present on the upgradient and downgradient sides of the fault, and older groundwater with unadjusted carbon-14 ages as old as 5,650 years before present was in water from wells within splays of the Lockhart fault, consistent with limited groundwater movement across the fault. As a result, groundwater and Cr(VI) released from the Hinkley compressor station moved to the northwest along the downgradient side of the fault. Coupled well-bore flow and depth-dependent water-quality data show water from wells C-01 and IW-03 within the Q4 2015 (October–December 2015) regulatory Cr(VI) plume was yielded from thin layers within the aquifer that are composed of well-sorted lake-margin (beach) deposits that likely have high lateral and longitudinal connectivity. Collectively, data show highly permeable deposits above the regional water table and thin permeable deposits within saturated portions of the upper aquifer that may have conducted groundwater and Cr(VI) downgradient when releases from the Hinkley compressor station first occurred.

California↗
USGS1982

Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1980

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, Houston, and San Antonio. Studies have been completed in the Dallas and Fort Worth areas. The Geological Survey, in cooperation with the Texas Department of Water Resources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones fault zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representatives watersheds under various types of urban development. To quantitatively appraise the ground-water resources along the Balcones fault zone, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the Edwards aquifer that is is hydrologic circulation with Barton Springs. This report presents the basic hydrologic data collected in the Austin urban area for the 1980 water year (Oct. 1, 1979 to Sept. 30, 1980). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-80-3, 1980.

Texas↗
USGS1985

Hydrologic data for urban studies in the Austin, Texas, metropolitan area, 1983

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the city of Austin, the program was expanded in 1975 to include additional streamflow and rainfall gaging stations, and the collection of surface water-quality data. In 1978, the program was expanded to include a ground-water resources study of the South Austin metropolitan area in the Balcones Fault Zone. The objectives of the Austin urban hydrology study are as follows: To determine, on the basis of historical data and hydrologic analyses, the magnitude and frequency of flood peaks and flood volume. To determine the effect of urban development on flood peaks and volume. To determine the variations in water quality during different seasons and flow conditions in representative watersheds under various types of urban development. To quantitatively appraise the ground-water resources along the Balcones Fault Zone, the effect of urbanization on the quality and quantity of recharge and discharge, and the extent of contamination in the Edwards aquifer that is in hydrologic circulation with Barton Springs. This report presents the basic hydrologic data collected in the Austin urban area for the 1983 water year (Oct. 1, 1982 to Sept. 30, 1983). Additional explanations of terms related to streamflow, water quality, and other hydrologic data used in this report are defined in the U.S. Geological Survey annual report Water Resources Data for Texas, TX-83-3, 1983.

Texas↗
USGS2003

Hydrologic Resources of Guam

Introduction The U.S. Territory of Guam, which lies in the western Pacific Ocean near latitude 13?28'N and longitude 144?45'E, is the largest (211 mi2) and southernmost of the islands in the Mariana chain. Ground water supplies about 80 percent of the drinking water for the island's 150,000 residents and nearly one million visitors per year. In northern Guam, water is obtained from wells that tap the upper part of a fresh ground-water lens in an aquifer composed mainly of limestone. About 180 wells, nearly all in the north, withdraw about 35 Mgal/d of water with chloride concentrations ranging from 6 to 585 mg/L. In southern Guam, the main source of freshwater is from surface water that runs off the weathered volcanic rocks that are exposed over much of the area. About 9.9 Mgal/d of freshwater is obtained using surface reservoirs. The island's freshwater resources are adequate to meet current (2003) needs, but future demands will eventually be higher. To better understand the hydrology of the island, the U.S. Geological Survey (USGS) entered into a cooperative study with the Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam. The objective of the study was to provide a better understanding of the water resources of the island through analysis of data collected by the USGS on Guam. This report provides a description of the general hydrologic principles of the island's ground-water systems, as well as of the rainfall and geology of Guam. Hydrologic data described in the report include water levels, chloride concentrations, and pumpage from ground-water wells and streamflow data from southern Guam.

Water-Resources Investigations Report↗
USGS1989

Hydrologic and chemical data for selected thermal-water wells and springs in the Indian Bathtub area, Owyhee County, southwestern Idaho

This report presents data collected during January through September 1989 from 86 thermal-water wells and 5 springs in the Indian Bathtub area, southwestern Idaho. The data include well and spring locations, well-construction and water level information, hydrographs of water levels in 9 wells, hydrographs of discharges in 4 springs, and chemical and isotopic analysis of water from 33 thermal-water wells and 5 springs. These data were collected as part of a continuing study to determine the cause or causes of decreased discharge at Indian Bathtub Spring and other thermal springs along Hot Creek.

Idaho↗
USGS1992

Ground-water-quality assessment of the central Oklahoma aquifer, Oklahoma: Hydrologic, water-quality, and quality-assurance data 1987-90

This report presents data collected from 202 wells between June 1987 and September 1990 as part of the Central Oklahoma aquifer pilot study of the National Water-Quality Assessment Program. The report describes the sampling networks, the sampling procedures, and the results of the ground-water quality and quality-assurance sample analyses. The data tables consist of information about the wells sampled and the results of the chemical analyses of ground water and quality-assurance sampling. Chemical analyses of ground-water samples in four sampling networks are presented: A geochemical network, a low-density survey bedrock network, a low-density survey alluvium and terrace deposits network, and a targeted urban network. The analyses generally included physical properties, major ions, nutrients, trace substances, radionuclides, and organic constituents. The chemical analyses of the ground-water samples are presented in five tables: (1) Physical properties and concentrations of major ions, nutrients, and trace substances; (2) concentrations of radionuclides and radioactivities; (3) carbon isotope ratios and delta values (d-values) of selected isotopes; (4) concentrations of organic constituents; and (5) organic constituents not reported in ground-water samples. The quality of the ground water sampled varied substantially. The sum of constituents (dissolved solids) concentrations ranged from 71 to 5,610 milligrams per liter, with 38 percent of the wells sampled exceeding the Secondary Maximum Contaminant Level of 500 milligrams per liter established under the Safe Drinking Water Act. Values of pH ranged from 5.7 to 9.2 units with 20 percent of the wells outside the Secondary Maximum Contaminant Level of 6.5 to 8.5 units. Nitrite plus nitrate concentrations ranged from less than 0.1 to 85 milligrams per liter with 8 percent of the wells exceeding the proposed Maximum Contaminant Level of 10 milligrams per liter. Concentrations of trace substances were highly variable, ranging from below the reporting level to concentrations over the Maximum Contaminant Levels for several constituents (arsenic, barium, cadmium, chromium, lead, and selenium). Radionuclide activities also were highly variable. Gross alpha radioactivity ranged from 0.1 to 210 picocuries per liter as 230thorium. Of the wells sampled, 20 percent exceeded the proposed Maximum Contaminant Level of 15 picocuries per liter for gross alpha radioactivity. Organic constituents were detected in 39 percent of the 170 wells sampled for organic constituents; in most cases concentrations were at or near the laboratory minimum reporting levels. Ten of the wells sampled for organic constituents had one or more constituents (chlordane, dieldrin, heptachlor epoxide, trichloroethylene, 1,1-dichloroethylene, 1,1,1-trichloroethane) at concentrations equal to or greater than the Maximum Contaminant Level or acceptable concentrations as suggested in the Environmental Protection Agency's Health Advisory Summaries. Quality-assurance sampling included duplicate samples, repeated samples, blanks, spikes, and blind samples. These samples proved to be essential in evaluating the accuracy of the data, particularly in the case of volatile organic constituents.

Oklahoma↗
USGS2013

Geology, water-quality, hydrology, and geomechanics of the Cuyama Valley groundwater basin, California, 2008--12

To assess the water resources of the Cuyama Valley groundwater basin in Santa Barbara County, California, a series of cooperative studies were undertaken by the U.S. Geological Survey and the Santa Barbara County Water Agency. Between 2008 and 2012, geologic, water-quality, hydrologic and geomechanical data were collected from selected sites throughout the Cuyama Valley groundwater basin. Geologic data were collected from three multiple-well groundwater monitoring sites and included lithologic descriptions of the drill cuttings, borehole geophysical logs, temperature logs, as well as bulk density and sonic velocity measurements of whole-core samples. Generalized lithologic characterization from the monitoring sites indicated the water-bearing units in the subsurface consist of unconsolidated to partly consolidated sand, gravel, silt, clay, and occasional cobbles within alluvial fan and stream deposits. Analysis of geophysical logs indicated alternating layers of finer- and coarser-grained material that range from less than 1 foot to more than 20 feet thick. On the basis of the geologic data collected, the principal water-bearing units beneath the monitoring-well sites were found to be composed of younger alluvium of Holocene age, older alluvium of Pleistocene age, and the Tertiary-Quaternary Morales Formation. At all three sites, the contact between the recent fill and younger alluvium is approximately 20 feet below land surface. Water-quality samples were collected from 12 monitoring wells, 27 domestic and supply wells, 2 springs, and 4 surface-water sites and were analyzed for a variety of constituents that differed by site, but, in general, included trace elements; nutrients; dissolved organic carbon; major and minor ions; silica; total dissolved solids; alkalinity; total arsenic and iron; arsenic, chromium, and iron species; and isotopic tracers, including the stable isotopes of hydrogen and oxygen, activities of tritium, and carbon-14 abundance. Of the 39 wells sampled, concentrations of total dissolved solids and sulfate from 38 and 37 well samples, respectively, were greater than the U.S. Environmental Protection Agency’s secondary maximum contaminant levels. Concentrations greater than the maximum contaminant levels for nitrate were observed in five wells and were observed for arsenic in four wells. Differences in the stable-isotopic values of hydrogen and oxygen among groundwater samples indicated that water does not move freely between different formations or between different zones within the Cuyama Valley. Variations in isotopic composition indicated that recharge is derived from several different sources. The age of the groundwater, expressed as time since recharge, was between 600 and 38,000 years before present. Detectable concentrations of tritium indicated that younger water, recharged since the early 1950s, is present in parts of the groundwater basin. Hydrologic data were collected from 12 monitoring wells, 56 domestic and supply wells, 3 surface-water sites, and 4 rainfall-gaging stations. Rainfall in the valley averaged about 8 inches annually, whereas the mountains to the south received between 12 and 19 inches. Stream discharge records showed seasonal variability in surface-water flows ranging from no-flow to over 1,500 cubic feet per second. During periods when inflow to the valley exceeds outflow, there is potential recharge from stream losses to the groundwater system Water-level records included manual quarterly depth-to-water measurements collected from 68 wells, time-series data collected from 20 of those wells, and historic water levels from 16 wells. Hydrographs of the manual measurements showed declining water levels in 16 wells, mostly in the South-Main zone, and rising water levels in 14 wells, mostly in the Southern Ventucopa Uplands. Time-series hydrographs showed daily, seasonal, and longer-term effects associated with local pumping. Water-level data from the multiple-well monitoring sites indicated seasonal fluctuations as great as 80 feet and water-level differences between aquifers as great as 40 feet during peak pumping season. Hydrographs from the multiple-well groundwater monitoring sites showed vertical hydraulic gradients were upward during the winter months and downward during the irrigation season. Historic hydrographs showed water-level declines in the Southern-Main, Western Basin, Caliente Northern-Main, and Southern Sierra Madre zone ranging from 1 to 7 feet per year. Hydrographs of wells in the Southern Ventucopa Uplands zone showed several years with marked increases in water levels that corresponded to increased precipitation in the Cuyama Valley. Investigation of hydraulic properties included hydraulic conductivity and transmissivity estimated from aquifer tests performed on 63 wells. Estimates of horizontal hydraulic conductivity ranged from about 1.5 to 28 feet per day and decreased with depth. The median estimated hydraulic conductivity for the older alluvium was about five times that estimated for the Morales Formation. Estimates of transmissivity ranged from 560 to 163,400 gallons per day per foot and decreased with depth. The median estimated transmissivity for the younger alluvium was about three times that estimated for the older alluvium. Geomechanical analysis included land-surface elevation changes at five continuously operating global positioning systems (GPS) and land-subsidence detection at five interferometric synthetic aperture radar (InSAR) reference points. Analysis of data collected from continuously operating GPS stations showed the mountains to the south and west moved upward about 1 millimeter (mm) annually, whereas the station in the center of the Southern-Main zone moved downward more than 7 mm annually, indicating subsidence. It is likely that this subsidence is inelastic (permanent) deformation and indicates reduced storage capacity in the aquifer sediments. Analysis of InSAR data showed local and regional changes that appeared to be dependent, in part, on the time span of the interferogram, seasonal variations in pumping, and tectonic uplift. Long-term InSAR time series showed a total maximum detected subsidence rate of approximately 12 mm per year at one location and approximately 8 mm per year at a second location, while short-term InSAR time series showed maximum subsidence of about 15 mm at one location and localized maximum uplift of about 10 mm at another location.

California↗
USGS2008

Water-Quality Characteristics of Ledge Creek and Holman Creek Upstream from Lake Rogers, Granville County, North Carolina, 2005 and 2008

Water-quality and hydrologic data were collected during 2005 and 2008 to characterize potential source areas of nutrients and sediment within the Ledge and Holman Creek watersheds upstream from Lake Rogers in Granville County, North Carolina. Eight monitoring locations were established in all--five in Holman Creek and three in Ledge Creek--for collecting discharge and water-quality data during different streamflow conditions. Water-quality samples were collected during two sampling events in the fall of 2005 for analysis of major ions, nutrients, suspended sediment, and fecal-indicator bacteria. Water-quality samples were collected during three sampling events in the winter and spring of 2008 for analysis of nutrients and suspended sediment.

North Carolina↗
USGS2009

Federal standards and procedures for the National Watershed Boundary Dataset (WBD)

The Watershed Boundary Dataset (WBD) is a seamless, national hydrologic unit dataset developed using the guidelines and specifications outlined in this document. A hydrologic unit defines the areal extent of surface-water drainage to an outlet point on a dendritic stream network or to outlet points where the stream network is not dendritic. A hydrologic unit may represent all or only part of the total drainage area to the outlet point so that multiple hydrologic units may be required to define the entire drainage area for a given outlet. Hydrologic unit boundaries in the WBD are determined on the basis of topographic, hydrologic, and other relevant landscape characteristics without regard for administrative, political, or jurisdictional boundaries. The WBD seamlessly represents hydrologic units at six required and two optional hierarchical levels mapped at a minimum of 1:24,000-scale in the United States, except for in Hawaii, the Caribbean, and the Pacific Islands, which are at 1:25,000-scale, and in Alaska, where the data range from the minimum required 1:24,000-scale to 1:63,360-scale. Hydrologic units in the WBD provide a standardized base for water-resources organizations to locate, store, retrieve, and exchange hydrologic data; to index and inventory hydrologic data and information; to catalog water-data acquisition activities; and to use in a variety of other applications. The specifications and procedures established in this document are intended to provide guidelines and best practices to local, regional, and national partners for delineating and updating the hydrologic units of the WBD. Maintaining the WBD using consistent practices improves watershed management through efficient sharing of information and resources and by ensuring that digital geographic data can be used with other related geographic information system data. Edits and additions to the hydrologic units are reviewed against this specification prior to inclusion to the national WBD.

Techniques and Methods↗
USGS1996

Status of ground-water resources at U.S. Navy Support Facility, Diego Garcia; summary of hydrologic and climatic data, January 1993 through September 1995

This report contains hydrologic and climatic data that describe the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data presented are from January 1993 through September 1995, although the report focuses on hydrologic events from July through September 1995. Cumulative rainfall for July through September 1995 was about 15 inches which is 32 percent less than the mean cumulative rainfall of about 22 inches for July through September. July and August are within the annual dry season, while September is the start of the annual wet season. Mean cumulative rainfall is calculated for the fixed base period 1951-90. Ground-water withdrawal during July through September 1995 averaged 888,500 gallons per day. Withdrawal for the same 3 months in 1994 averaged 919,400 gallons per day. Patterns of withdrawal during the third quarter of 1995 did not change significantly since 1993 at all five ground-water production areas. At the end of September 1995, the chloride concentration of the composite water supply was 51 milligrams per liter, well below the 250 milligrams per liter secondary drinking-water standard established by the U.S. Environmental Protection Agency. Chloride concentrations of the composite water supply from July through September 1995 ranged between 42 and 68 milligrams per liter. Chloride concentration of ground water in monitoring wells at Cantonment and Air Operations continued to increase since April 1995, with water from the deepest monitoring wells increasing in chloride concentration by as much as 2,000 milligrams per liter. A fuel leak at Air Operations caused the shutdown of ten wells in May 1991. Four of the wells resumed pumping for water-supply purposes in April 1992. The remaining six wells are being used to hydraulically divert fuel migration away from water-supply wells by recirculating about 150,000 gallons of water each day.

Open-File Report↗
USGS1983

Potential effects of surface coal mining on the hydrology of the Greenleaf-Miller area, Ashland coal field, southeastern Montana

The Greenleaf-Miller area of the Ashland coal field contains reserves of Federal coal that have been identified for potential lease sale. A hydrologic study was conducted in the potential lease area in 1981 to describe the existing hydrologic system and to assess potential impacts of surface coal mining on local water resources. The hydrologic data collected from wells, test holes, and springs were used to identify aquifers in the alluvium (Pleistocene and Holocene age) and the Tongue River member of the Fort Union Formation (Paleocene age). Coal, clinker, and sandstone beds comprise the aquifers in the Tongue River Member. Most streams are ephemeral and flow only as a result of precipitation. The only perennial surface-water flow in the study area is along short reaches downstream from springs. A mine plan for the area is not available; thus, the location of mine cuts, direction and rate of the mine expansion, and duration of mining are unknown. The mining of the Sawyer and Knoblock coal beds in the Tonge River Member would effect ground-water flow in the area. Declines in the potentiometric surface would be caused by dewatering where the mine pits intersect the water table. Wells and springs would be removed in the mine area; however, deeper aquifers are available as replacement sources of water. The chemical quality of the ground water would change after moving through the spoils. The change would be an increase in the concentration of dissolved solids. (USGS)

Montana↗