SEARCH · Search USGS

Results for “Ground-water Report”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 415 records · Page 23Linked to original sources

USGS2007

Ground-Water Flow Model for the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

This report presents a computer model of ground-water flow in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in Spokane County, Washington, and Bonner and Kootenai Counties, Idaho. The aquifer is the sole source of drinking water for more than 500,000 residents in the area. In response to the concerns about the impacts of increased ground-water withdrawals resulting from recent and projected urban growth, a comprehensive study was initiated by the Idaho Department of Water Resources, the Washington Department of Ecology, and the U.S. Geological Survey to improve the understanding of ground-water flow in the aquifer and of the interaction between ground water and surface water. The ground-water flow model presented in this report is one component of this comprehensive study. The primary purpose of the model is to serve as a tool for analyzing aquifer inflows and outflows, simulating the effects of future changes in ground-water withdrawals from the aquifer, and evaluating aquifer management strategies. The scale of the model and the level of detail are intended for analysis of aquifer-wide water-supply issues. The SVRP aquifer model was developed by the Modeling Team formed within the comprehensive study. The Modeling Team consisted of staff and personnel working under contract with the Idaho Department of Water Resources, personnel working under contract with the Washington Department of Ecology, and staff of the U.S. Geological Survey. To arrive at a final model that has the endorsement of all team members, decisions on modeling approach, methodology, assumptions, and interpretations were reached by consensus. The ground-water flow model MODFLOW-2000 was used to simulate ground-water flow in the SVPR aquifer. The finite-difference model grid consists of 172 rows, 256 columns, and 3 layers. Ground-water flow was simulated from September 1990 through September 2005 using 181 stress periods of 1 month each. The areal extent of the model encompasses an area of approximately 326 square miles. For the most part, the model extent coincides with the 2005 revised extent of the Spokane Valley-Rathdrum Prairie aquifer as defined in a previous report. However, the model excludes Spirit and Hoodoo Valleys because of uncertainties about the ground-water flow directions in those valleys and the degree of hydraulic connection between the valleys and northern Rathdrum Prairie. The SVRP aquifer is considered to be a single hydrogeologic unit except in Hillyard Trough and the Little Spokane River Arm. In those areas, a continuous clay layer divides the aquifer into an upper, unconfined unit and a lower, confined unit. The model includes all known components of inflows to and outflows from the aquifer. Inflows to the SVRP aquifer include (1) recharge from precipitation, (2) inflows from tributary basins and adjacent uplands, (3) subsurface seepage and surface overflows from lakes that border the aquifer, (4) flow from losing segments of the Spokane River to the aquifer, (5) return percolation from irrigation, and (6) effluent from septic systems. Outflows from the SVRP aquifer include (1) ground-water withdrawals from wells, (2) flow from the aquifer to gaining segments of the Spokane River, (3) aquifer discharge to the Little Spokane River, and (4) subsurface outflow from the lower unit at the western limit of the model area near Long Lake. These inflow and outflow components are represented in the model by using MODFLOW-2000 packages. The parameter-estimation program PEST was used to calibrate the SVRP aquifer model. PEST implements a nonlinear least-squares regression method to estimate model parameters so that the differences between measured and simulated quantities are minimized with respect to an optimal criterion. Calibration data include 1,573 measurements of water levels and 313 measurements of streamflow gains and losses along segments of the Spokane and Little Spokane Rivers. Model parameters estimated during calib

Scientific Investigations Report↗

USGS1983

Ground-water quality data for Oklahoma, 1981

The U.S. Geological Survey has collected data on Oklahoma's ground-water resources since 1934. Most of these data were collected as part of specific ground-water studies conducted in cooperation with various Federal, State, and local agencies. Ground-water quality data, as well as data on construction, yield, water levels, and other physical well parameters collected prior to 1981 are available from the U.S. Geological Survey, Oklahoma District Office. Although water-quality data for wells, test holes, and springs have been published, they are scattered though a variety of reports and are not readily available on a statewide basis. The purpose of this report is to make available, annually, all of the ground-water quality data collected by the U.S. Geological Survey in the Sate of Oklahoma. This report contains ground-water quality data collected in 1981 from 524 sites in 15 counties, predominately in eastern Oklahoma.

Open-File Report↗

USGS1982

Annual summary of ground-water conditions in Arizona, Spring 1981 to Spring 1982

The withdrawal of ground water was about 5.4 million acre-feet in Arizona in 1981, which is about 800,000 acre-feet more than the amount withdrawn in 1980. Most of the increase in 1981 was in the amount of ground water used for irrigation in the Basin and Range lowlands province. Through 1981, slightly more than 189 million acre-feet of ground water had been withdrawn from the ground-water reservoirs in Arizona. The report contains two small-scale maps that show ground-water pumpage by areas and the status of the ground-water inventory in the State. The main map, which is at a scale of 1:500,000, shows potential well production, depth to water in selected wells in spring 1982, and change in water level in selected wells from 1977 to 1982. A brief text summarizes the current ground-water conditions in the State. (USGS)

Open-File Report↗

USGS1984

Annual summary of ground-water conditions in Arizona, spring 1982 to spring 1983

The withdrawal of ground water was slightly less than 4.2 million acre-feet in Arizona in 1982, which is about 1.2 million acre-feet less than the amount withdrawn in 1981. Most of the decrease in 1982 was in the amount of ground water used for irrigation in the Basin and Range lowlands province. Through 1982, slightly more than 193 million acre-feet of ground water had been withdrawn from the ground-water reservoirs in Arizona. The report contains three small-scale maps that show ground-water pumpage by areas, the status of the ground-water inventory and observation-well program, and the ground-water quality sampling program. The main map, which is at a scale of 1:500,000, shows potential well production, depth to water in selected wells in spring 1983, and change in water level in selected wells from 1978 to 1983. A brief text summarizes the current ground-water conditions in the State. (USGS)

Open-File Report↗

USGS2006

Hydrology and simulation of ground-water flow, Lake Point, Tooele County, Utah

Water for new residential development in Lake Point, Utah may be supplied by public-supply wells completed in consolidated rock on the east side of Lake Point. Ground-water flow models were developed to help understand the effect the proposed withdrawal will have on water levels, flowing-well discharge, spring discharge, and ground-water quality in the study area. This report documents the conceptual and numerical ground-water flow models for the Lake Point area. The ground-water system in the Lake Point area receives recharge from local precipitation and irrigation, and from ground-water inflow from southwest of the area. Ground water discharges mostly to springs. Discharge also occurs to evapotranspiration, wells, and Great Salt Lake. Even though ground water discharges to Great Salt Lake, dense salt water from the lake intrudes under the less-dense ground water and forms a salt-water wedge under the valley. This salt water is responsible for some of the high dissolved-solids concentrations measured in ground water in Lake Point. A steady-state MODFLOW-2000 ground-water model of Tooele Valley adequately simulates water levels, ground-water discharge, and ground-water flow direction observed in Lake Point in 1969 and 2002. Simulating an additional 1,650 acre-feet per year withdrawal from wells causes a maximum projected drawdown of about 550 feet in consolidated rock near the simulated wells and drawdown exceeding 80 feet in an area encompassing most of the Oquirrh Mountains east of Lake Point. Drawdown in most of Lake Point ranges from 2 to 10 ft, but increases to more than 40 feet in the areas proposed for residential development. Discharge to Factory Springs, flowing wells, evapotranspiration, and Great Salt Lake is decreased by about 1,100 acre-feet per year (23 percent). The U.S. Geological Survey SUTRA variable-density ground-water-flow model generates a reasonable approximation of 2002 dissolved-solids concentration when simulating 2002 withdrawals. At most locations with measured dissolved-solids concentration in excess of 1,000 milligrams per liter, the model simulates salt-water intrusion with similar concentrations. Simulating an additional 1,650 acre-feet per year withdrawal increased simulated dissolved-solids concentration by 200 to 1,000 milligrams per liter throughout much of Lake Point and near Factory Springs at a depth of about 250 to 300 feet below land surface. The increase in dissolved-solids concentration with increased withdrawals is greater at a depth of about 700 to 800 feet and exceeds 1,000 milligrams per liter throughout most of Lake Point. At the north end of Lake Point, increases exceed 10,000 milligrams per liter.

Utah↗

USGS1996

Status of ground-water resources at U.S. Navy Support Facility, Diego Garcia; summary of hydrologic and climatic data, January 1994 through March 1996

This report describes the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data presented are from January 1994 through March 1996, with a focus on data from January through March 1996 (first quarter of 1996). A complete database of ground-water withdrawals and chloride-concentration records since 1985 is maintained by the U.S. Geological Survey. Cumulative rainfall for January through March 1996 was about 30 inches, which is 9 percent less than the mean cumulative rainfall of about 33 inches for January through March. The period January through February is the end of the annual wet season, while March marks the start of the annual dry season. Ground-water withdrawal during January through March 1996 averaged 970,300 gallons per day. Withdrawal for the same 3 months in 1995 averaged 894,600 gallons per day. With- drawal patterns during the first quarter of 1996 did not change significantly since 1991, with the Cantonment and Air Operations areas supplying about 99 percent of total islandwide pumpage. At the end of March 1996, the chloride concentration of water from the elevated tanks at Cantonment and Air Operations were 47 and 80 milligrams per liter, respectively. The chloride data from all five production areas showed no significant upward or downward trends throughout the first quarter of 1996. Potable levels of chloride concentrations have been maintained by adjusting individual pumping rates, and also because of the absence of long-term droughts. Chloride concentration of ground water in monitoring wells at Cantonment and Air Operations also showed no significant trends throughout the first quarter of 1996. Chloride concentrations have been about the same since the last quarter of 1995. A fuel-pipeline leak at Air Operations in May 1991 decreased total islandwide withdrawals by 15 percent. This lost pumping capacity is being offset by increased pumpage at Cantonment. Six wells do not contribute to the water supply because they are being used to hydraulically divert fuel migration away from water-supply wells by a program of ground-water withdrawal and injection.

Open-File Report↗

USGS1996

Status of ground-water resources at U.S. Navy Support Facility, Diego Garcia; summary of hydrologic and climatic data, January 1994 through June 1996

This report describes the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data presented are from January 1994 through June 1996, with a focus on data from April through June 1996 (second quarter of 1996). A complete database of ground-water withdrawals and chloride-concentration records since 1985 is maintained by the U.S. Geological Survey. Cumulative rainfall for April through June 1996 was 22.64 inches, which is 12 percent more than the mean cumulative rainfall of 20.21 inches for April through June. The period April through June is part of the annual dry season. Ground-water withdrawal during April through June 1996 averaged 1,048,000 gallons per day. Withdrawal for the same 3 months in 1995 averaged 833,700 gallons per day. Withdrawal patterns during the second quarter of 1996 did not change significantly since 1991, with the Cantonment and Air Operations areas supplying about 99 percent of total islandwide pumpage. At the end of June 1996, the chloride concentration of water from the elevated tanks at Cantonment and Air Operations were 52 and 80 milligrams per liter, respectively. The chloride data from all five production areas showed no significant upward or downward trends throughout the second quarter of 1996. Potable levels of chloride concentrations have been maintained by adjusting individual pumping rates, and also because of the absence of long-term droughts. Chloride concentration of ground water in monitoring wells at Cantonment and Air Operations also showed no significant trends throughout the second quarter of 1996. Chloride concentrations have been about the same since the last quarter of 1995. A fuel-pipeline leak at Air Operations in May 1991 decreased total islandwide withdrawals by 15 percent. This lost pumping capacity is being offset by increased pumpage at Cantonment. Six wells do not contribute to the water supply because they are being used to hydraulically divert fuel migration away from water-supply wells by a program of ground-water withdrawal and injection.

Open-File Report↗

USGS1997

Digital data sets that describe aquifer characteristics of the Elk City Aquifer in western Oklahoma

ARC/INFO export and nonproprietary format files This diskette contains digitized aquifer boundaries and maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the Elk City aquifer in western Oklahoma. The aquifer covers an area of approximately 193,000 acres and supplies ground water for irrigation, domestic, and industrial purposes in Beckham, Custer, Roger Mills, and Washita Counties along the divide between the Washita and Red River basins. The Elk City aquifer consists of the Elk City Sandstone and overlying terrace deposits, made up of clay, silt, sand and gravel, and dune sands in the eastern part and sand and gravel of the Ogallala Formation (or High Plains aquifer) in the western part of the aquifer. The Elk City aquifer is unconfined and composed of very friable sandstone, lightly cemented with clay, calcite, gypsum, or iron oxide. Most of the grains are fine-sized quartz but the grain size ranges from clay to cobble in the aquifer. The Doxey Shale underlies the Elk City aquifer and acts as a confining unit, restricting the downward movement of ground water. All of the data sets were digitized and created from information and maps in a ground-water modeling thesis and report of the Elk City aquifer. The maps digitized were published at a scale of 1:63,360. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

Oklahoma↗

USGS1984

Ground-water level data and preliminary potentiometric-surface maps, Yucca Mountain and vicinity, Nye County, Nevada

The report contains a table of ground-water level data and two preliminary potentiometric-surface maps for the Yucca Mountain area. The water-level surface shown on the maps generally represents water-table (unconfined) conditions. The water table in the Yucca Mountain area occurs in ash-flow and air-fall tuffs of tertiary age. West of the crest of Yucca Mountain, water-level altitudes are about 775 meters above sea level. Along the eastern edge and southern end of Yucca Mountain, the potentiometic surface generally is nearly flat, is about 728 to 730 meters above sea level, and has a southeastward slope. (USGS)

Water-Resources Investigations Report↗

USGS2004

Geohydrology of the French Creek Basin and simulated effects of drought and ground-water withdrawals, Chester County, Pennsylvania

This report describes the results of a study by the U.S. Geological Survey, in cooperation with the Delaware River Basin Commission, to develop a regional ground-water-flow model of the French Creek Basin in Chester County, Pa. The model was used to assist water-resource managers by illustrating the interconnection between ground-water and surface-water systems. The 70.7-square mile French Creek Basin is in the Piedmont Physiographic Province and is underlain by crystalline and sedimentary fractured-rock aquifers. Annual water budgets were calculated for 1969-2001 for the French Creek Basin upstream of streamflow-measurement station French Creek near Phoenixville (01472157). Average annual precipitation was 46.28 in. (inches), average annual streamflow was 20.29 in., average annual base flow determined by hydrograph separation was 12.42 in., and estimated average annual ET (evapotranspiration) was 26.10 in. Estimated average annual recharge was 14.32 in. and is equal to 31 percent of the average annual precipitation. Base flow made up an average of 61 percent of streamflow. Ground-water flow in the French Creek Basin was simulated using the finite-difference MODFLOW-96 computer program. The model structure is based on a simplified two-dimensional conceptualization of the ground-water-flow system. The modeled area was extended outside the French Creek Basin to natural hydrologic boundaries; the modeled area includes 40 square miles of adjacent areas outside the basin. The hydraulic conductivity for each geologic unit was calculated from reported specific-capacity data determined from aquifer tests and was adjusted during model calibration. The model was calibrated for above-average conditions by simulating base-flow and water-level measurements made on May 1, 2001, using a recharge rate of 20 in/yr (inches per year). The model was calibrated for below-average conditions by simulating base-flow and water-level measurements made on September 11 and 17, 2001, using a recharge rate of 6.2 in/yr. Average conditions were simulated by adjusting the recharge rate until simulated streamflow at streamflow-measurement station 01472157 matched the long-term (1968-2001) average base flow of 54.1 cubic feet per second. The recharge rate used for average conditions was 15.7 in/yr. The effect of drought in the French Creek Basin was simulated using a drought year recharge rate of 8 in/yr for 3 months. After 3 months of drought, the simulated streamflow of French Creek at streamflow-measurement station 01472157 decreased 34 percent. The simulations show that after 6 months of average recharge (15.7 in/yr) following drought, streamflow and water levels recovered almost to pre-drought conditions. The effect of increased ground-water withdrawals on stream base flow in the South Branch French Creek Subbasin was simulated under average and drought conditions with pumping rates equal to 50, 75, and 100 percent of the Delaware River Basin Commission Ground Water Protected Area (GWPA) withdrawal limit (1,393 million gallons per year) with all pumped water removed from the basin. For average recharge conditions, the simulated streamflow of South Branch French Creek at the mouth decreased 18, 28, and 37 percent at a withdrawal rate equal to 50, 75, and 100 percent of the GWPA limit, respectively. After 3 months of drought recharge conditions, the simulated streamflow of South Branch French Creek at the mouth decreased 27, 40, and 52 percent at a withdrawal rate equal to 50, 75, and 100 percent of the GWPA limit, respectively. The effect of well location on base flow, water levels, and the sources of water to the well was simulated by locating a hypothetical well pumping 200 gallons per minute in different places in the Beaver Run Subbasin with all pumped water removed from the basin. The smallest reduction in the base flow of Beaver Run was from a well on the drainage divide between the French Creek Basin and the Marsh Creek Basin to the south; the simulated base flow of Beaver Run at the mouth was reduced 1 percent. The greatest reduction in the base flow of Beaver Creek was from a well close to Beaver Run; the simulated base flow of Beaver Run at the mouth was reduced 8 percent. The simulations showed that (1) if the contributing area of a well is in a basin, pumping will affect stream base flow and water levels in that basin whether the well is inside or outside that basin; (2) wells in different areas of a basin away from a divide produce a similar reduction in base flow; (3) a well within a basin will derive more water from diverted base flow and less water from storage than a well on or near a basin divide; and (4) the reduction in base flow at the mouth of the stream is the same for a well in the headwaters and a well downstream near the confluence. Model simulations illustrate some of the typical analyses and results that can be produced. The model was calibrated using annual values for recharge and ground-water ET and then was run using the annual values in a seasonally independent transient mode to show changes with time. The timing and relative magnitude of some of the changes simulated with the model when viewed in terms of a normal climatic year may be subject to considerable uncertainty because of the variability in seasonal recharge and ground-water ET rates. Transient model simulations for short-term periods are indicative of possible hydrologic system response and are considered an approximation.

Pennsyvlania↗

USGS1963

Ground-water geology and pump irrigation in Frenchman Creek Basin above Palisade, Nebraska

This report describes the geography, geology, and ground-water resources of that part of the Frenchman Creek basin upstream from Palisade, Nebr., an area of about 4,900 square miles. The basin includes all of Phillips County, Colo., and Chase County, Nebr., and parts of Logan, Sedgwick, Washington, and Yuma Counties, Colo., and Dundy, Hayes, Hitchcock, and Perkins Counties, Nebr. The land surface ranges from nearly flat to rolling; choppy hills and interdune saddles are common in the areas of dune sand, and steep bluffs and gullies cut the edges of the relatively flat loess plateaus. Most of the basin is drained by tributaries of Frenchman Creek, but parts of the sandhills are undrained. Farming and livestock raising are the principal industries. Irrigation with ground water has expanded rapidly since 1934. The rocks exposed in the basin are largely unconsolidated and range in age from Pliocene to Recent. They comprise the Ogallala formation (Pliocene), the Sanborn formation (Pleistocene and Recent?), dune sand (Pleistocene and Recent), and alluvium (Recent). The rocks underlying the Ogallala are the Pierre shale (Late Cretaceous) and the White River group (Oligocene). The Pierre shale is relatively impermeable and yields little or no water to wells. The White River group also is relatively impermeable and yields little or no water to wells; however, small to moderate quantities of water possibly may be obtained from wells that penetrate fractured or 'porous' zones in the upper part of the White River group or permeable channel deposits within the group. The Ogallala formation is the main aquifer in the basin and yields moderate to large quantities of water to wells. The Sanborn formation and the dune sand generally lie above the water table, but in areas of high water table the dune sand yields small quantities of water to wells for domestic and stock supplies. The alluvium, which includes the low terrace deposits bordering the major streams, yields small to large quantities of water to wells. The ground-water reservoir is recharged only from precipitation on the basin. Of the average annual precipitation of 19.5 inches, about 0.9 inch infiltrates to the water table, thereby contributing about 220,000 acre-feet of water annually to the ground-water reservoir. About 81 million acre-feet of water that could drain under gravity, and thus theoretically is available to wells, is held in groundwater storage in the basin. Water is discharged from the ground-water reservoir by wells, evaporation and transpiration, springs, seepage into streams, and movement into adjacent areas to the east and southeast. Most of the domestic, stock, and irrigation water supplies and all the public supplies are pumped from wells. During 1953, 96 wells were used to irrigate 10,000 acres of land with 19,000 acre-feet of water. About 34,000 acre-feet of water is evaporated and transpired annually in the valleys of the main streams and in areas of shallow water table in the sandhills. From the projection of base-flow measurements made during 1952, it was estimated that the average annual flow of Frenchman Creek into the reservoir above Enders Dam is about 57,000 acre-feet. By similar determinations, the average annual flow of Frenchman Creek at the gaging station at Palisade, Nebr., about 22 miles downstream from Enders Dam, is about 76,000 acre-feet, and the flow of Stinking Water Creek at the gaging station near Palisade is about 22,000 acre-feet. The combined flow of Frenchman and Stinking Water Creeks at their confluence near Palisade thus is about 98,000 acre-feet per year. About 90,000 acre-feet of ground water is estimated to move eastward each year across the Colorado-Nebraska State line within the basin. Additional irrigation wells that will tap the Ogallala formation and the alluvium in the major valleys undoubtedly will be drilled. On the basis of current estimates of future irrigation.withdrawals, it is concluded that by the

Water Supply Paper↗

USGS2006

Estimation of shallow ground-water recharge in the Great Lakes basin

This report presents the results of the first known integrated study of long-term average ground-water recharge to shallow aquifers (generally less than 100 feet deep) in the United States and Canada for the Great Lakes, upper St. Lawrence, and Ottawa River Basins. The approach used was consistent throughout the study area and allows direct comparison of recharge rates in disparate parts of the study area. Estimates of recharge are based on base-flow estimates for streams throughout the Great Lakes Basin and the assumption that base flow in a given stream is equal to the amount of shallow ground-water recharge to the surrounding watershed, minus losses to evapotranspiration. Base-flow estimates were developed throughout the study area using a single model based on an empirical relation between measured base-flow characteristics at streamflow-gaging stations and the surficial-geologic materials, which consist of bedrock, coarse-textured deposits, fine-textured deposits, till, and organic matter, in the surrounding surface-water watershed. Model calibration was performed using base-flow index (BFI) estimates for 959 stations in the U.S. and Canada using a combined 28,784 years of daily streamflow record determined using the hydrograph-separation software program PART. Results are presented for watersheds represented by 8-digit hydrologic unit code (HUC, U.S.) and tertiary (Canada) watersheds. Recharge values were lowest (1.6-4.0 inches/year) in the eastern Lower Peninsula of Michigan; southwest of Green Bay, Wisconsin; in northwestern Ohio; and immediately south of the St. Lawrence River northeast of Lake Ontario. Recharge values were highest (12-16.8 inches/year) in snow shadow areas east and southeast of each Great Lake. Further studies of deep aquifer recharge and the temporal variability of recharge would be needed to gain a more complete understanding of ground-water recharge in the Great Lakes Basin.

Great Lakes Basin↗

USGS1980

Ground-water data for Georgia, 1979

This report continues a publication format that annually presents both water-level and water-quality data. In this format the information is presented in two-page units: the left page presents a text which summarizes the information for an area or subject and the right page consists of one or more illustrations. Daily mean water-level fluctuations and trends are shown in hydrographs for the previous year and fluctuations of the monthly mean water level for the previous 10 years in selected observation wells in Georgia. The selected wells best illustrate the effects of changes in recharge and discharge in the various ground-water reservoirs in the State A short narrative explains fluctuations and trends in each hydrograph. Monitoring ground-water levels is essential to the understanding of storage changes and other changes in a ground-water reservoir or aquifer. Fluctuations and long-term trends in water levels occur as a result of recharge to and discharge from the reservoir. Varying rates of recharge occur chiefly as a result of varying rates of precipitation, evapotranspiration, and surface-water infiltration into the ground-water reservoir. Discharge occurs as natural flow from the aquifer to streams and springs, direct ground-water evapotranspiration, and as manmade withdrawal from wells. Ground-water levels have been monitored in Georgia for at least a hundred years. Most of the data gathered were used in area 1 reconnaissance studies, and published, usually as tables, with a few graphs of water-level trends. These data had limited value, especially considering the time lag between data collection and publication. With the advent of continuously monitoring recorders and computer processing of data, this information can now be presented to the user in an understandable and timely manner.

Georgia↗

USGS1988

Ground-water data for Georgia, 1987

This report was prepared in cooperation with the State of Georgia; Chatham County; Glynn County; the cities of Brunswick and Valdosta; and the Albany Water, Gas, and Light Commission. This report is the culmination of a concerted effort by dedicated personnel of the U.S. Geological Survey who collected, compiled, analyzed, verified, and organized the data, and who edited and assembled the report. In addition to the authors, who had primary responsibility for assuring that the information contained herein is accurate, complete, and adheres to Geological Survey policy and established guidelines, the following individuals contributed significantly to the collection, processing, and tabulation of the data:

Georgia↗

USGS1984

An overview of ground-water quality data in Wisconsin

This report contains a summary of ground-water-quality data for Wisconsin and an evaluation of the adequacy of these data for assessing the impact of land disposal of wastes on ground-water quality. Chemical analyses used in data summaries were limited to those stored in the USGS computer system (WATSTORE). Information on documented instances of ground-water contamination and sources of potential contamination from land disposal of wastes was provided by the Wisconsin Department of Natural Resources. Available data provide an overview of ground water quality but may be insufficient for assessment of ground-water contamination from land disposal of wastes. Many sources of potential ground-water contamination (landfills, surface waste-storage impoundments, and buried tanks) are known. Some of these are probably causing local ground-water contamination that is not apparent from available regional data. Information needs for assessment of ground-water contamination from land disposal of wastes include improved understanding of both ground-water hydrology and the chemical behavior of specific contaminants in the environment. (USGS)

Wisconsin↗

USGS1983

Evaluation of ground-water quality data from Kentucky

The report reviews and summarizes 10,578 chemical analyses, from 2,362 wells and springs in Kentucky. These water-quality data were collected prior to September 30, 1981, and are available in computer files of the U.S. Geological Survey. The principal water-bearing rocks in Kentucky were combined into 10 major groups to aid in data summary preparation and general description of the ground-water quality of the State. Ground water in Kentucky is generally fresh near the outcrop of the rocks comprising the aquifer. Slightly saline to briny water occurs at variable depths beneath the freshwater. Preparation of quadrilinear diagrams revealed three principal geochemical processes in the aquifers of Kentucky: (1) mixing of freshwater and saline water in an interface zone; (2) dedolomitization of the Devonian and Silurian and Lower Mississippian carbonate rocks; (3) sodium for calcium exchange in the freshwater sections of many of the sandstone-shale aquifers. A number of errors and deficiencies were found in the data base. The principal deficiencies were: (1) very few complete analyses which included important field measurements; (2) inadequate definition of the chemistry of the freshwater-saline water interface zone throughout much of the State; (3) no analyses of stable isotopes and dissolved gases; (4) fewer than 10 analyses of most trace metals, radionuclides, and man-made organic chemicals; and (5) no data on bacteria in ground water from any aquifer in the State. (USGS)

Kentucky↗

USGS1960

Ground-water areas and well logs, Central Sevier Valley, Utah

Between September 1959 and June 1960 the United States Geological Survey and the Utah State Engineer, with financial assistance from Garfield, Millard, Piute, Sanpete, and Sevier Counties and from local water-users' associations, cooperated in an investigation to determine the structural framework of the central Sevier Valley and to evaluate the valley's ground-water potential. An important aspect of the study was the drilling of 22 test holes under private contract. These data and other data collected during the course of the larger ground-water investigation of which the test drilling was a part will be evaluated in a report on the geology and ground-water resources of the central Sevier Valley. The present report has been prepared to make available the logs of the test holes and to describe in general terms the availability of ground water in the different areas of the valley. The test holes were located to determine the subsurface geology of the valley, but of principal interest for this report is the water-bearing materials that were penetrated by the test holes. Ten of the holes penetrated materials capable of yielding sufficient water for irrigation; 10 holes penetrated water-yielding materials that could supply water for domestic or stock use; 2 holes were unsuccessful as water prospects but supplied geologic information. Generally, the water in the test holes was of good quality for stock, domestic, or irrigation use, except in test holes 1, 2, 4, 5, 16, 17, and 19 where water from some beds was highly mineralized. Water from the upper water-bearing bed in test holes 1, 2, 4, 5 and 16 and from the 6 upper water-bearing beds in test hole 19 was high in sodium chloride and sodium sulphate and would be unpalatable to humans and stock. The upper water in test hole 17 would be palatable to stock accustomed to brackish water, but the water from below 78 feet is too saline for any use. The central Sevier Valley has been divided into arbitrary ground-water areas that are based in part on topographic and geologic boundaries. The test holes are described by areas downstream from south to north, and the logs of table 1 are arranged from south to north.

Utah↗

USGS2001

MODFLOW-2000 : the U.S. Geological Survey modular ground-water model--documentation of the Advective-Transport Observation (ADV2) Package

Observations of the advective component of contaminant transport in steady-state flow fields can provide important information for the calibration of ground-water flow models. This report documents the Advective-Transport Observation (ADV2) Package, version 2, which allows advective-transport observations to be used in the three-dimensional ground-water flow parameter-estimation model MODFLOW-2000. The ADV2 Package is compatible with some of the features in the Layer-Property Flow and Hydrogeologic-Unit Flow Packages, but is not compatible with the Block-Centered Flow or Generalized Finite-Difference Packages. The particle-tracking routine used in the ADV2 Package duplicates the semi-analytical method of MODPATH, as shown in a sample problem. Particles can be tracked in a forward or backward direction, and effects such as retardation can be simulated through manipulation of the effective-porosity value used to calculate velocity. Particles can be discharged at cells that are considered to be weak sinks, in which the sink applied does not capture all the water flowing into the cell, using one of two criteria: (1) if there is any outflow to a boundary condition such as a well or surface-water feature, or (2) if the outflow exceeds a user specified fraction of the cell budget. Although effective porosity could be included as a parameter in the regression, this capability is not included in this package. The weighted sum-of-squares objective function, which is minimized in the Parameter-Estimation Process, was augmented to include the square of the weighted x-, y-, and z-components of the differences between the simulated and observed advective-front locations at defined times, thereby including the direction of travel as well as the overall travel distance in the calibration process. The sensitivities of the particle movement to the parameters needed to minimize the objective function are calculated for any particle location using the exact sensitivity-equation approach; the equations are derived by taking the partial derivatives of the semi-analytical particle-tracking equation with respect to the parameters. The ADV2 Package is verified by showing that parameter estimation using advective-transport observations produces the true parameter values in a small but complicated test case when exact observations are used. To demonstrate how the ADV2 Package can be used in practice, a field application is presented. In this application, the ADV2 Package is used first in the Sensitivity-Analysis mode of MODFLOW-2000 to calculate measures of the importance of advective-transport observations relative to head-dependent flow observations when either or both are used in conjunction with hydraulic-head observations in a simulation of the sewage-discharge plume at Cape Cod, Massachusetts. The ADV2 Package is then used in the Parameter-Estimation mode of MODFLOW-2000 to determine best-fit parameter values. It is concluded that, for this problem, advective-transport observations improved the calibration of the model and the estimation of ground-water flow parameters, and the use of formal parameter-estimation methods and related techniques produced significant insight into the physical system.

Open-File Report↗