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At least 487 records · Page 27Linked to original sources
USGS1994

Use of landsat thematic mapper data to identify crop types and estimate irrigated acreage, Uvalde and Medina counties, Texas, 1991

Landsat Thematic Mapper (TM) data were used to estimate that about 51,000 acres of crops were irrigated with water pumped from the Edwards aquifer in Uvalde and Medina Counties, Texas in 1991. Bands 2, 3,4, and 5 from a TM image for August 10,1991, were classified using the maximum-likelihood, unsupervised-classification procedure to identify the areas of crops irrigated in the two counties. Detailed vegetation distribution maps of two calibration sites in the study area, and boundaries of the areas probably irrigated in 1991, were used to interpret the results and to separate probable irrigated areas by county from the rest of the image. Areas calculated for irrigated crops were 31,000 acres for Uvalde County, about 35 percent less than the area calculated using Landsat multispectral scanner (MSS) data in 1989, and 20,000 acres for Medina County, about 13 percent less than in 1989, a total decrease of about 28 percent for the two counties. Quantities of water pumped from the Edwards aquifer to irrigate crops in 1991 were estimated as 65,000 acre-feet for Uvalde County and 18,000 acre-feet for Medina County, a total decrease of about 56 percent from the value calculated using crop acreages from MSS data for 1989. Differences were attributed primarily to greater precipitation in 1991 than in 1989, resulting in smaller irrigation water requirements and less supplemental irrigation in 1991. Differences between results from 1989 and 1991, and between results from Uvalde and Medina Counties in 1991, were attributed primarily to greater precipitation in 1991, particularly in Medina County. The total number of acres of irrigated crops estimated using Landsat TM data was about 9 percent lower in Uvalde County and about 13 percent lower in Medina County than the number of acres calculated from data reported by the U.S. Department of Agriculture, Agricultural Stabilization and Conservation Service (ASCS). The total quantity of water pumped from the Edwards aquifer for irrigation in the two counties in 1991, about 83,000 acre-feet, was about 5 percent greater than the quantity calculated from data reported by the ASCS.

Texas↗
USGS1964

Water resources of Van Buren County, Michigan

The water resources of Van Buren County include productive ground-water reservoirs, a network of perennial streams, about 60 major inland lakes, and Lake Michigan. Most water users obtain their supplies from wells. The ground-water reservoirs in the glacial drift can provide several times the amount of water now used, but large withdrawals of ground water may lower the levels of nearby lakes or diminish the flow of nearly streams. Permeable soils and drift account for the relatively high base flows of streams in the southeastern two-thirds of the county. Less permeable surficial materials in the northwest part of the county result in relatively low base flows there. The water from wells is generally hard and high in iron content but is otherwise suitable for most uses. Water from streams and lakes is similar to that from wells except that iron-content is not a problem, and some of the inland lakes have very soft water. The availability of ground water, the base flow of streams, and the chemical character of water in the county are summarized in maps and tables accompanying this report.

Michigan↗
USGS1989

Geologic studies in Alaska by the U.S. Geological Survey, 1988

This volume continues the annual series of U.S. Geological Survey (USGS) reports on geologic investigations in Alaska. Since 1975, when the first of these collections of short papers appeared under the title "The United States Geological Survey in Alaska: Accomplishments during 1975," the series has been published as USGS circulars. This bulletin departs from the circular style, in part to provide a more flexible format for longer reports with more depth of content, better documentation, and broader scope than is possible for circular articles. The 13 papers in this bulletin represent a sampling of research activities carried out in Alaska by the USGS over the past few years. The topics addressed range from mineral resource studies (including natural gas) and geochemistry, Quaternary geology, basic stratigraphic and structural problems, and the use of computer graphics in geologic map preparation, to the application of geochronology to regional tectonic problems. Geographic areas represented are numbered on figure 1 and include the North Slope (1) and Brooks Range (2, 3) of Arctic Alaska, Seward Peninsula (4), interior Alaska (5-9), and remote locations of the Alaska Peninsula (10, 11) and southeast Alaska (12, 13). Two bibliographies following the reports of investigations list (1) reports about Alaska in USGS publications released in 1988 and (2) reports about Alaska by USGS authors in publications outside the USGS in 1988. A bibliography and index of the short papers in past USGS circulars devoted to Geological Research and Accomplishments in Alaska (1975-1986) is published as USGS Open-File Report 87-420.

Alaska↗
USGS1988

Bibliography of hydrologic and water-quality investigations conducted in or near the Albermarle-Pamlico Sounds Region, North Carolina

A bibliography containing 1,100 citations is presented. The cited works are primarily reports of investigations of the effects of land use and land-use change on water quality, artificial drainage, hydrology and hydrodynamics, and water quality in the Albemarle-Pamlico Sounds region, North Carolina. The bibliography is indexed according to research topic and geographic location of the investigation. the bibliography is also computerized and has been transferred to the Albemarle-Pamlico Estuarine Study data-management system.

Open-File Report↗
USGS2008

Aquifer Tests and Characterization of Transmissivity, Ada-Vamoosa Aquifer on the Osage Reservation, Osage County, Oklahoma, 2006

The Ada-Vamoosa aquifer of northeastern Oklahoma is a sedimentary bedrock aquifer of Pennsylvanian age that crops out over 800 square miles of the Osage Reservation. The Osage Nation needed additional information regarding the production potential of the aquifer to aid them in future development planning. To address this need, the U.S. Geological Survey, in cooperation with the Osage Nation, conducted a study of aquifer properties in the Ada-Vamoosa aquifer. This report presents the results of the aquifer tests from 20 wells in the Ada-Vamoosa aquifer and one well in a minor aquifer east of the Ada-Vamoosa outcrop on the Osage Reservation. Well information for 17 of the 21 wells in this report was obtained from the Indian Health Service. Data collected by the U.S. Geological Survey during this investigation are pumping well data from four domestic wells collected during the summer of 2006. Transmissivity values were calculated from well pumping data or were estimated from specific capacity values depending on the reliability of the data. The estimated transmissivity values are 1.1 to 4.3 times greater than the calculated transmissivity values. The calculated and estimated transmissivity values range from 5 to 1,000 feet squared per day.

Scientific Investigations Report↗
USGS1975

Progress report on the water resources investigation of Martin County, Florida

The base of the shallow aquifer ranges from 125 feet (38 m) below sea level in the northwest part of Martin County to about 280 feet (85.3 m) below sea level in the southeast part of the county. Test holes also indicate a thick, highly permeable zone in the east part of the county which becomes thinner and interlaced with zones of lower permeability in the west part. Water levels decline about 2 to 5 feet (0.6 to 1.5 m) during the dry season (October 1973 to May 1974) in most areas of Martin County. Within the area influenced by the pumping of Stuart's public supply wells, water level declined 6 feet (1.8 m) between October 1973 and May 1974. Water levels during January - May 1974 in this area were 3 to 6 feet (0.0 to 1.8 m) lower than they were in January - May 1965. This difference was due to a three-fold increase in pumpage (0.8 to 2 mgd) from 1965 to 1974. Chloride concentrations in four salt water monitoring wells around the Stuart well field ranged from 35 to 45 mg/1 during the rainy season of 1973. No appreciative increase in chlorides was found by the end of the next dry season. Water from five surface water sites had higher concentrations of phosphorus than water found in a typical urban area in Fort Lauderdale. Water from seven sites contained concentrations of nitrogen less than the typical rural site average. Expansion of the test drilling program, observation of salt-water intrusion, water-level monitoring and continued nutrient sampling are planned for future study. An interpretative report will be prepared at the end of this investigation.

Florida↗
USGS2004

Changes in streamflow and water quality in selected nontidal sites in the Chesapeake Bay Basin, 1985-2003

Water-quality and streamflow data from 33 sites in nontidal portions of the Chesapeake Bay Basin were analyzed to document annual nutrient and sediment loads and trends for 1985 through 2003 as part of an annual evaluation of water-quality conditions by the Chesapeake Bay Program. As part of this study, different trend tests and methodologies were evaluated for future use in assessment of the effectiveness of management actions in reducing nutrients and sediments to the Chesapeake Bay. Trends in streamflow were tested at multiple time scales (daily, monthly, seasonal, and annual), resulting in only one significant trend (annual flow for Choptank River near Greensboro, Md.). Data summaries for observed concentrations indicate higher ranges in total-nitrogen concentrations in the northern five major river basins in Pennsylvania, Maryland, and Virginia compared to the southern five basins in Virginia. Similar comparisons showed no distinct differences for total phosphorus. Flow-weighted concentration is useful in evaluating changes through time for the Susquehanna, Potomac, and James Rivers. Results indicate the Potomac River had the highest flow-weighted concentrations (2.5 milligrams per liter) for total nitrogen, and the Potomac and James Rivers averaged about the same (0.15 milligram per liter) for total-phosphorus concentrations. Flow-weighted concentrations were lowest in the Susquehanna River for phosphorus and sediment because of the trapping efficiency of three large reservoirs upstream from the sampling point. Annual loads were estimated by use of the U.S. Geological Surveys ESTIMATOR model. Annual nutrient and sediment loads in 2003 were the second highest total nitrogen, total phosphorus, and sediment loads for the River Input Monitoring sites since 1990. Trends in concentrations, when adjusted for flow, can be used as an indicator of human activity and management actions. The flow-adjusted trends indicated significant decreasing trends at approximately 55, 75, and 48 percent of the sites for total nitrogen, total phosphorus, and sediment, respectively. This suggests management actions are having some effect in reducing nutrients and sediments. Sampling protocols for the river inputs to the bay have targeted high flows. Because this sampling strategy creates the potential for bias in estimated loads and trends, calculations are limited to flow-adjusted loads and trends in this report.

Scientific Investigations Report↗
USGS2010

Completion Summary for Well NRF-16 near the Naval Reactors Facility, Idaho National Laboratory, Idaho

In 2009, the U.S. Geological Survey in cooperation with the U.S. Department of Energy's Naval Reactors Laboratory Field Office, Idaho Branch Office cored and completed well NRF-16 for monitoring the eastern Snake River Plain (SRP) aquifer. The borehole was initially cored to a depth of 425 feet below land surface and water samples and geophysical data were collected and analyzed to determine if well NRF-16 would meet criteria requested by Naval Reactors Facility (NRF) for a new upgradient well. Final construction continued after initial water samples and geophysical data indicated that NRF-16 would produce chemical concentrations representative of upgradient aquifer water not influenced by NRF facility disposal, and that the well was capable of producing sustainable discharge for ongoing monitoring. The borehole was reamed and constructed as a Comprehensive Environmental Response Compensation and Liability Act monitoring well complete with screen and dedicated pump. Geophysical and borehole video logs were collected after coring and final completion of the monitoring well. Geophysical logs were examined in conjunction with the borehole core to identify primary flow paths for groundwater, which are believed to occur in the intervals of fractured and vesicular basalt and to describe borehole lithology in detail. Geophysical data also were examined to look for evidence of perched water and the extent of the annular seal after cement grouting the casing in place. Borehole videos were collected to confirm that no perched water was present and to examine the borehole before and after setting the screen in well NRF-16. Two consecutive single-well aquifer tests to define hydraulic characteristics for well NRF-16 were conducted in the eastern SRP aquifer. Transmissivity and hydraulic conductivity averaged from the aquifer tests were 4.8 x 103 ft2/d and 9.9 ft/d, respectively. The transmissivity for well NRF-16 was within the range of values determined from past aquifer tests in other wells near NRF of 4.4 x 102 to 5.1 x 105 ft2/d. Water samples were analyzed for metals, nutrients, total organic carbon, volatile organic compounds, semi-volatile organic compounds, herbicides, pesticides, polychlorinated biphenols, and radionuclides. All chloride, nitrate, and sulfate concentrations were less than background concentrations for the eastern SRP aquifer north of the NRF. Concentrations in water samples for most of the organic compounds and radionuclides were less than the reporting limits and reporting levels.

Scientific Investigations Report↗
USGS2014

Estimates of inorganic nitrogen wet deposition from precipitation for the conterminous United States, 1955-84

The U.S. Geological Survey’s National Water-Quality Assessment program requires nutrient input information for analysis of national and regional assessment of water quality. Historical data are needed to lengthen the data record for assessment of trends in water quality. This report provides estimates of inorganic nitrogen deposition from precipitation for the conterminous United States for 1955–56, 1961–65, and 1981–84. The estimates were derived from ammonium, nitrate, and inorganic nitrogen concentrations in atmospheric wet deposition and precipitation-depth data. This report documents the sources of these data and the methods that were used to estimate the inorganic nitrogen deposition. Tabular datasets, including the analytical results, precipitation depth, and calculated site-specific precipitation-weighted concentrations, and raster datasets of nitrogen from wet deposition are provided as appendixes in this report.

Scientific Investigations Report↗
USGS2015

Baseline water-quality sampling to infer nutrient and contaminant sources at Kaloko-Honokōhau National Historical Park, Island of Hawai‘i, 2009

Baseline water-quality sampling was conducted for dissolved nutrients and for chemical and isotopic tracers at Kaloko-Honokōhau National Historical Park on the Island of Hawai'i. Existing and future urbanization in the surrounding areas have the potential to affect water quality in the Park, and so the National Park Service and the U.S. Geological Survey designed a water-sampling strategy to document baseline conditions against which future changes can be compared. Sites in and near the Park were sampled twice, in July and December 2009, and included four anchialine pools, two large fishponds, five monitoring wells, an upland production well, tap water, and a holding pond for golf-course irrigation water. Water samples within the coastal park were brackish, ranging in salinity from 15 to 67 percent seawater. Samples were analyzed for dissolved inorganic nutrients (nitrogen and phosphorus), stable isotopes (nitrogen and oxygen in dissolved nitrate; hydrogen and oxygen in the water molecule), pharmaceuticals, wastewater compounds, and volatile organic compounds. A case of acute, but temporary, fertilizer contamination was evident along the Park's north boundary during the turf grow-in period of a newly constructed golf course. A maximum nitrogen concentration 280 percent above background level was measured in monitoring well MW401 in July, later falling to 109 percent above background by December. Two nearby sites (MW400 and AP 144) had nitrogen concentrations that were elevated compared to remaining sites but less severely than at MW401. Aside from this localized fertilizer influence, other water samples had lower nutrient enrichments: 40 percent or less above background for nitrogen and 57 percent or less above background for phosphorus. Background was defined in this study by a graphical mixing line between saltwater from a deep well in the Park and freshwater at a reference well in the mountainous uplands (Honokōhau production well, at 1,675 ft altitude). Potential nutrient sources between the uplands and coastal lowlands that could contribute to enrichment include rock weathering, natural vegetation, fertilizers, septic leachate, and atmospheric deposition – including motor-vehicle exhaust. Some fraction of septic leachate is expected in groundwater because there are unsewered suburban and commercial developments upslope from the Park that rely on cesspools and septic systems. However, stable isotopes of nitrate did not implicate septic-waste nitrogen (heavy δ 15 N values on the order of +10 per mil or greater). Instead, the heaviest δ 15 N values of +6 to +8 per mil were associated with the large fishponds, likely as a result of biotic cycling. Water samples with δ 15 N values of +3 to +5 per mil were still isotopically heavier than the upland groundwater value of +2 per mil and likely reflect addition of heavier nitrogen, possibly from septic sources, nitrogen-fixing vegetation, or vehicular exhaust. Pharmaceuticals, wastewater compounds, and volatile organic compounds indicated that if contamination is present, it appears to be at low, barely detectable, levels--at least as reflected by the results of this study. The most diagnostic indication of septic contamination was at monitoring well KAHO 2, closest to Kaloko Light Industrial Park, where three pharmaceuticals (carbamazepine, sulfamethoxazole, and thiobendazole) were detected at trace-level parts-per-trillion concentrations. A screening-level test for laundry fabric brighteners indicated positive detection at most sites; however, readings were quite low and if laundry graywater is present, it appears to be a small, dilute fraction. Because the weather was persistently dry throughout the study period, the USGS team was unable to conduct a wet-weather “storm” sampling. Wet-weather results are expected to differ from those reported here, though by how much remains unknown.

Hawai‘i↗
USGS2026

Evaluating chlorophyll fluorescence sensors as a proxy for chlorophyll a concentrations in the Illinois River, Illinois, water years 2018–24

The U.S. Geological Survey deployed instream chlorophyll fluorescence sensors on the Illinois River in Illinois to better understand the formation, dynamics, and persistence of riverine algal blooms. At five sensor locations across four U.S. Geological Survey streamgages, chlorophyll fluorescence (fChl) sensors were set to measure instantaneous fChl in micrograms per liter as chlorophyll at 15-minute intervals. These sensors estimate fChl based on the fluorescence response of algal pigments but do not directly measure chlorophyll a (Chl) concentrations or algal biomass. To evaluate the reliability of fChl as a proxy for Chl, fChl measurements were compared to laboratory-measured Chl concentrations. These Chl concentrations were obtained from water-quality samples collected at the sensor locations and analyzed using the standard chromatographic-fluorometric method with acetone extraction. A total of 209 paired fChl and Chl observations were analyzed using Pearson’s correlation and model II regression. Statistically significant, positive correlations (Pearson’s correlation coefficient of 0.68–0.95) were detected at all sensor locations, indicating that fChl generally tracked with Chl. However, model II regression detected proportional and fixed bias at three of the five locations and proportional bias at another location. At locations with proportional biases, model II regression slopes were less than 1, indicating that fChl increasingly underestimated Chl as concentrations increased; however, paired observations at high Chl concentrations were sparse. Substantial variability in bias was also observed across sensor locations with slopes ranging from 0.43 to 0.93. Overall, the results indicated that fChl correlates well with Chl in the Illinois River, but fChl may not reliably represent Chl concentrations without adjustment. For applications requiring accurate Chl estimates, a sensor location-specific surrogate model could be beneficial. These findings underscore the importance of field validation, consistent sensor placement, and careful interpretation of fChl data, particularly when reported in micrograms per liter.

Illinois, Indiana, Wisconsin↗
USGS1987

Methods for the determination of organic substances in water and fluvial sediments

This manual describes analytical methods used by the U.S. Geological Survey to determine organic substances in water, water-suspended-sediment mixtures, and bottom material. Some of the analytical procedures yield determinations for specific com-pounds, whereas others provide a measure of the quantity of groups of compounds present in the sample. Examples of the first category are procedures for the organochlorine and organophosphate insecticides, chlorophenoxy acid and triazine herbicides, and specific substituted phenols. Examples of the second category are the various organic carbon analyses and the polychlorinated biphenyl methods. The analytical methods are presented in a standard format; topics covered include conditions for application of the method, a summary of the method, interferences, required apparatus and reagents, analytical procedures, calculations, reporting of results, and estimation of precision.

Techniques of Water-Resources Investigations↗
USGS2003

Percentile distributions of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations in Oklahoma streams, 1973-2001

Nutrients are one of the primary causes of water-quality impairments in streams, lakes, reservoirs, and estuaries in the United States. The U.S. Environmental Protection Agency has developed regional-based nutrient criteria using ecoregions to protect streams in the United States from impairment. However, nutrient criteria were based on nutrient concentrations measured in large aggregated nutrient ecoregions with little relevance to local environmental conditions in states. The Oklahoma Water Resources Board is using a dichotomous process known as Use Support Assessment Protocols to define nutrient criteria in Oklahoma streams. The Oklahoma Water Resources Board is modifying the Use Support Assessment Protocols to reflect nutrient informa-tion and environmental characteristics relevant to Oklahoma streams, while considering nutrient information grouped by geographic regions based on level III ecoregions and state boundaries. Percentile distributions of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorous concentrations were calculated from 563 sites in Oklahoma and 4 sites in Arkansas near the Oklahoma and Arkansas border to facilitate development of nutrient criteria for Oklahoma streams. Sites were grouped into four geographic regions and were categorized into eight stream categories by stream slope and stream order. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations were greater in the Ozark Highland ecoregion and were less in the Ouachita Mountains ecoregion when compared to other geographic areas used to group sites. The 50th percentiles of median concentrations of nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus were least in first, second, and third order streams. The 50th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen and total phosphorus concentrations in the Ozark Highland and Ouachita Mountains ecoregions were least in first, second, and third order streams with streams slopes greater than 17 feet per mile. Nitrite plus nitrate as nitrogen and total nitrogen criteria determined by the U.S. Environmental Protection Agency for the Ozark Highland ecoregion were less than the 25th percentiles of median nitrite plus nitrate as nitrogen, total nitrogen, and total phosphorus concentrations in the Ozark Highland ecoregion calculated for this report. Nitrite plus nitrate as nitrogen and total nitrogen criteria developed by the U.S. Environmental Protection Agency for the Ouachita Mountains ecoregion were similar to the 25th percentiles of median nitrite plus nitrate as nitrogen and total nitrogen concentrations in the Ouachita Mountains ecoregion calculated for this report. Nitrate as nitrogen and total phosphorus concentrations currently (2002) used in the Use Support Assessment Protocols for Oklahoma were greater than the 75th percentiles of median nitrite plus nitrate as nitrogen and total phosphorus concentrations calculated for this report.

Oklahoma↗
USGS1987

Pesticide data for selected Wyoming streams, 1976-78

In 1976, the U.S. Geological Survey, in cooperation with the Wyoming Department of Agriculture, started a monitoring program to determine pesticide concentrations in Wyoming streams. This program was incorporated into the water-quality data-collection system already in operation. Samples were collected at 20 sites for analysis of various insecticides, herbicides, polychlorinated biphenyls, and polychlorinated napthalenes.\ The results through 1978 revealed small concentrations of pesticides in water and bottom-material samples were DDE (39 percent of the concentrations equal to or greater than the minimum reported concentrations of the analytical methods), DDD (20 percent), dieldrin (21 percent), and polychlorinated biphenyls (29 percent). The herbicides most commonly found in water samples were 2,4-D (29 percent of the concentrations equal to or greater than the minimum reported concentrations of the analytical method) and picloram (23 percent). Most concentrations were significantly less than concentrations thought to be harmful to freshwater aquatic life based on available toxicity data. However for some pesticides, U.S. Environmental Protection Agency water-quality criteria for freshwater aquatic life are based on bioaccumulation factors that result in criteria concentrations less than the minimum reported concentrations of the analytical methods. It is not known if certain pesticides were present at concentrations less than the minimum reported concentrations that exceeded these criteria.

Wyoming↗
USGS1985

Management of ground water and evolving hydrogeologic studies in New Jersey : a heavily urbanized and industrialized state in the northeastern United States

New Jersey is the most densely populated and one of the most industrialized states in the United States. An abundance of freshwater and proximity to major northeastern metropolitan centers has facilitated this development. Pumpage of freshwater from all aquifers in the State in 1980 was 730 million gallons per day (2.76 million cubic meters per day). Management and efficient development of the ground-water resources of the State are the responsibility of the New Jersey Department of Environmental Protection. Laws have been enacted and updated by the State legislature to manage water allocation and to control the disposal of hazardous wastes. Present resource management is guided by the New Jersey Water-Supply Master Plan of 1981. Funding for management activities is partially derived from the sale of state-approved bonds. Effective planning and regional management require accurate and up-to-date hydrologic information and analyses. The U.S. Geological Survey, in cooperation with the New Jersey Geological Survey, is conducting three intensive ground-water studies involving the collection and interpretation of hydrologic data to meet the urgent water-management needs of New Jersey. These studies are part of a long-term cooperative program and are funded through the Water-Supply Bond Act of 1981. They began in 1983 and are scheduled to be completed in 1988. The project areas are situated in the New Jersey part of the Atlantic Coastal Plain in and near Atlantic City, Camden, and South River. They range in size from 400 to 1,200 mil (1,040 to 3,120 km2). The studies are designed to define the geology, hydrology, and geochemistry of the local ground-water systems. The results of these studies will enable the State to address more effectively major problems in these areas such as declining water levels, overpumping, saltwater intrusion, and ground-water contamination resulting from the improper disposal of hazardous wastes. Specific objectives of these studies by the U.S. Geological Survey are to (1) develop an accurate and up-to-date hydrogeologic data base, (2) design and implement a data-collection program and establish a computerized information management system, (3) refine the conceptualization of the ground-water flow system, and (4) define the geochemistry of the aquifer system by conducting a water-quality appraisal. The objectives are accomplished by standard hydrogeologic methods. Information concerning hydrogeologic framework, ground-water levels, water use, hydraulic characteristics, and water quality in the study areas is compiled from all available sources. Additional data needed are collected through well inventories, surface geophysical surveys, water-quality samplings, water-level measurements, and a well-drilling program. Interpretation of the flow system is based on the use of standard analytical techniques and digital flow modeling. Calibrated flow models will provide ground-water managers with a mechanism to develop and test regional water-supply strategies. Definition of the geochemistry of the aquifer system is accomplished through a variety of methods which depend on the problems and available data in the particular study area. The approach includes statistical analysis of water-quality data, reaction-path modeling, and determination of the movement of chemical constituents using analytical and numerical modeling techniques. A combined staff of 25 to 30 professionals and technicians from the New Jersey District office of the U.S. Geological Survey is committed to the three studies. The staff has specialists in geohydrology, numerical modeling, geochemistry, geophysics, and computer science. The findings of these studies will be published in data reports, interpretive reports, instructional manuals and journal articles.

New Jersey↗