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USGS2000

Ground-water quality atlas of Oakland County, Michigan

The U.S. Geological Survey (USGS), in cooperation with Oakland County Health Division (OCHD), collected 140 water samples from 38 wells in Oakland County during 1998 to better understand ground-water quality. OCHD had observed temporal variations in concentrations of various constituents, so two additional sets of samples were collected to evaluate potential short-term variability related to sample collection procedures and long-term seasonal variability. Replicate samples from 28 wells were analyzed in the Michigan Department of Environmental Quality (MDEQ) Drinking Water Laboratory to compare MDEQ’s analytical results to those obtained from the USGS National Water Quality Laboratory. Several additional databases describing population, land use, water supply, soils, geology, and flows of ground water and surface water are presented in the first part of the report to assist in interpreting the water-quality data. Maps created from these databases are provided in the first portion of the report as an extension of the study-area description. The U.S. Environmental Protection Agency (USEPA) has established Maximum Contaminant Levels (MCL) and Secondary Maximum Contaminant Levels (SMCL) for which samples were analyzed in this study. Water from the 38 wells sampled by the USGS did not exceed the SMCL or MCL for sulfate, fluoride, or nitrite. However, water from 26 wells exceeded the SMCL for iron, water from 12 wells exceeded the SMCL for manganese, and water from 12 wells exceeded the SMCL for dissolved solids. Water from two wells exceeded the MCL for nitrate, although nitrate concentrations in water from most wells was below the detection limit. Water from seven wells exceeded the SMCL for chloride, and water from all wells contained detectable concentrations of chloride. Water from five wells exceeded the MCL for arsenic, and most of the wells sampled contained detectable concentrations of arsenic. These five wells were identified from previous MDEQ analyses to have elevated arsenic concentrations, and were sampled to obtain additional chemistry information. Replicate samples were collected from 26 of the 38 wells for analysis at the MDEQ Drinking-Water Laboratory to compare the results with the USGS National Water Quality Laboratory. The results of the replicate analyses indicate close agreement between the laboratories, with mean differences for nitrate, chloride, and arsenic of 0.10 milligrams per liter (mg/L) as nitrogen, 6.8 mg/L, and 0.0008 mg/L, respectively between the USGS and MDEQ analyses. Potential health effects associated with ingesting nitrate, chloride, and arsenic are provided with the water-quality data, along with references for further information.

Michigan↗

USGS1995

Determination of base-flow characteristics at selected streamflow-gaging stations on the Mad River, Ohio

This report describes the results of a study to estimate characteristics of base flow and sustained ground-water discharge at five streamflow-gaging stations on the Mad River in Ohio. The five streamflow-gaging stations are located at Zanesfield, near Urbana, at St. Paris Pike (at Eagle City), near Springfield, and near Dayton. The median of the annual-mean base flows, determined by means of hydrograph separation, ranged from 0.64 (ft3/s)/mi2 (cubic feet per second per square mile) at Zanesfield to 0.74 (ft3/s)/mi2 at St. Paris Pike. The median percentage of annual total streamflow attributed to base flow ranged from 61.8 percent at Zanesfield to 76.1 percent near Urbana. Estimates of an upper limit (or threshold) at which base flows can be considered to be composed predominately of sustained ground-water discharge were made by constructing and analyzing base- flow-duration curves. The sustained ground-water discharges (base flows less than or equal to the estimated sustained ground-water-discharge thresholds) are assumed to originate from ground-water- flow systems that are minimally affected by seasonal climatic changes. The median sustained ground- water discharge ranged from 0.11 (ft3/s)/mi2 at Zanesfield to 0.26 (ft3/s)/mi2 at St. Paris Pike (at Eagle City) and near Springfield. The median sustained ground-water discharge, expressed as a percentage of the median annual-mean base flow, ranged from 17.2 percent at Zanesfield to 38.6 percent near Springfield.

Water-Resources Investigations Report↗

USGS1985

Ground-water quality in east-central New Jersey, and a plan for sampling networks

Groundwater quality was evaluated in seven confined aquifers and the water table aquifer in east-central New Jersey based on 237 analyses of samples collected in 1981-82, and 225 older analyses. Investigation of the effect of land use on water quality and several sampling network proposals for the region are reported. Generally, water in the confined aquifers is of satisfactory quality for human consumption and most other uses. Iron (Fe) and manganese (Mn) concentrations exceed U.S. EPA drinking water standards in some wells screened in the Potomac-Raritan-Magothy aquifer system. Sodium (Na) concentrations in samples from three wells more than 800 ft deep in the Englishtown aquifer exceed the standard. Iron and Mn concentrations in this aquifer may also exceed the standards. Iron concentrations in the Wenonah-Mount Laurel aquifer exceed the standard. Based on 15 analyses of water from the Vincetown aquifer, Mn is the only constituent that exceeds the drinking water standard. In the Manasquan aquifer, 4 of the 16 Na determinations exceed the standard, and 8 of 16 Fe determinations exceed the standard. Water quality in the Atlantic City 800-ft sand is generally satisfactory. However, 12 Fe and 1 of 12 Mn determinations exceed the standards. For the Rio Grande water-bearing zone, 1 of 3 Fe determinations exceed the standard. The Kirkwood-Cohansey aquifer system (the water table aquifer) was the most thoroughly sampled (249 chemical analyses from 209 wells). Dissolved solids, chloride, Fe, nitrate, and Mn concentrations exceed drinking water standards in some areas. The results of chi-square tests of constituent distributions based on analyses from 158 wells in the water table aquifer indicate that calcium is higher in industrial and commercial areas; and Mg, chloride, and nitrate-plus-nitrite is higher in residential areas. (Author 's abstract)

Water-Resources Investigations Report↗

USGS1995

Environmental and hydrologic setting of the Ozark Plateaus study unit, Arkansas, Kansas, Missouri, and Oklahoma

The environmental and hydrologic setting of the Ozark Plateaus National Water-Quality Assessment (NAWQA) study unit and the factors that affect water quality are described in this report. The primary natural and cultural features that affect water- quality characteristics and the potential for future water-quality problems are described. These environmental features include climate, physio- graphy, geology, soils, population, land use, water use, and surface- and ground-water flow systems. The study-unit area is approximately 47,600 square miles and includes most of the Ozark Plateaus Province and parts of the adjacent Osage Plains and Mississippi Alluvial Plain in parts of Arkansas, Kansas, Missouri, and Oklahoma. The geology is characterized by basement igneous rocks overlain by a thick sequence of dolomites, limestones, sandstones, and shales of Paleozoic age. Land use in the study unit is predominantly pasture and forest in the southeastern part, and pasture and cropland in the northwestern part. All or part of the White, Neosho-lllinois, Osage, Gasconade, Meramec, St. Francis, and Black River Basins are within the study unit. Streams in the Boston Mountains contain the least mineralized water, and those in the Osage Plains contain the most mineralized water. The study unit contains eight hydrogeologic units including three major aquifers--the Springfield Plateau, Ozark, and St. Francois aquifers. Streams and aquifers in the study unit generally contain calcium or calcium-magnesium bicarbonate waters. Ground- and surface-water interactions are greatest in the Salem and Springfield Plateaus and least in the Boston Mountains and Osage Plains. Geology, land use, and population probably are the most important environmental factors that affect water quality.

Water-Resources Investigations Report↗

USGS1997

Occurrence of dissolved solids, nutrients, atrazine, and fecal coliform bacteria during low flow in the Cheney Reservoir watershed, south-central Kansas, 1996

A network of 34 stream sampling sites was established in the 1,005-square-mile Cheney Reservoir watershed, south-central Kansas, to evaluate spatial variability in concentrations of selected water-quality constituents during low flow. Land use in the Cheney Reservoir watershed is almost entirely agricultural, consisting of pasture and cropland. Cheney Reservoir provides 40 to 60 percent of the water needs for the city of Wichita, Kansas. Sampling sites were selected to determine the relative contribution of point and nonpoint sources of water-quality constituents to streams in the watershed and to identify areas of potential water-quality concern. Water-quality constituents of interest included dissolved solids and major ions, nitrogen and phosphorus nutrients, atrazine, and fecal coliform bacteria. Water from the 34 sampling sites was sampled once in June and once in September 1996 during Phase I of a two-phase study to evaluate water-quality constituent concentrations and loading characteristics in selected subbasins within the watershed and into and out of Cheney Reservoir. Information summarized in this report pertains to Phase I and was used in the selection of six long-term monitoring sites for Phase II of the study. The average low-flow constituent concentrations in water collected during Phase I from all sampling sites was 671 milligrams per liter for dissolved solids, 0.09 milligram per liter for dissolved ammonia as nitrogen, 0.85 milligram per liter for dissolved nitrite plus nitrate as nitrogen, 0.19 milligram per liter for total phosphorus, 0.20 microgram per liter for dissolved atrazine, and 543 colonies per 100 milliliters of water for fecal coliform bacteria. Generally, these constituents were of nonpoint-source origin and, with the exception of dissolved solids, probably were related to agricultural activities. Dissolved solids probably occur naturally as the result of the dissolution of rocks and ancient marine sediments containing large salt deposits. Nutrients also may have resulted from point-source discharges from wastewater-treatment plants. An examination of water-quality characteristics during low flow in the Cheney Reservoir watershed provided insight into the spatial variability of water-quality constituents and allowed for between-site comparisons under stable-flow conditions; identified areas of the watershed that may be of particular water-quality concern; provided a preliminary evaluation of contributions from point and nonpoint sources of contamination; and identified areas of the watershed where long-term monitoring may be appropriate to quantify perceived water-quality problems.

Water-Resources Investigations Report↗

USGS1988

Geohydrology of Indian River County, Florida

The surficial aquifer system and the Floridan aquifer system are the sources of groundwater used in Indian River County, Florida. About 65% of the groundwater is used for irrigation and is from the Floridan aquifer system. Saline water ranging from slightly saline to brine underlies the fresh groundwater throughout the county and is the chief water quality problem. Transmissivities of the surficial aquifer system in eastern Indian River County range from 1,500 to 11,000 sq ft/d. Yields of wells are as much as 1,200 gal/min. Reported transmissivities for the Floridan aquifer system range from 65,000 to 200,000 sq ft/d. Most wells that tap the Floridan aquifer system flow; flow rates range from 30 to 2,000 gal/min. Chloride concentrations of water in the surficial aquifer system generally are below 100 mg/L, but concentrations often exceed 250 mg/L in water from the Floridan aquifer system. Between 1976 and 1983, average chloride concentrations in water from six wells that tap the surficial aquifer system in the Vero Beach well field increased about 36 mg/L, but were unchanged in four other wells. The increase in chloride concentration probably is related to a well-field pumpage increase from 5.44 million gal/d in 1976 to 8.00 million gal/d in 1983. In most of the County, chloride concentrations of wells that tap the Floridan aquifer system have not changed significantly in the 15-year period, 1968-83. Water levels in the surficial aquifer system declined 15 to 19 ft between 1971 and 1984 in the Vero Beach well field where the larger groundwater withdrawals occur, but have not declined significantly outside heavily pumped areas. Water levels in the Floridan aquifer system have declined 16 to 24 ft in eastern Indian River County in the 50-year period, 1934-84, but declines outside the heavily pumped areas generally have been less than 10 ft during this period. (USGS)

Water-Resources Investigations Report↗

USGS1996

Summary of biological investigations relating to water quality in the Western Lake Michigan Drainages, Wisconsin and Michigan

This report summarizes aquatic biological studies relevant to water-quality assessment that have been done in the Western Lake Michigan Drainages from 1891 to 1996. The objective of the summary was to compile sources of biological data for the U.S. Geological Survey's National Water-Quality Assessment Program. The studies are divided into four categories: (1) populations and community structure of aquatic biota, (2) health of aquatic biota, (3) chemical concentrations in tissues of aquatic biota, and (4) toxicity tests by use of aquatic biota. Studies are further categorized by subbasin, spatial scale (regional or local), types of biota, and, if applicable, effect or contaminant investigated. For the purposes of this report, the study area is divided into five subbasins. The subbasins, from north to south, are (1) the Ford/Escanaba Subbasin in Michigan's Upper Peninsula, and in Wisconsin, (2) the Menominee/ Oconto/Peshtigo Subbasin, (3) the Fox/Wolf Subbasin, (4) the Sheboygan/Manitowoc/Twin Subbasin, and (5) the Milwaukee Subbasin. Most biological studies related to waterquality conditions in the Western Lake Michigan Drainages have focused on populations and community structure of aquatic biota. Chemical concentrations in tissues of aquatic biota have been the next most common area of research. Our review suggests a paucity of data related to the health of all types of aquatic biota, especially amphibians, invertebrates, and reptiles; toxicity studies also were relatively uncommon. Overall, organisms primarily studied have been fish and invertebrates, although birds are most frequently examined in studies of organism health. The Fox/ Wolf Subbasin has been the focus of many more studies than the other subbasins, most likely because of the greater extent and severity of known water-quality problems in the Lower Fox River/Green Bay area over the past several decades and because it is the largest subbasin. Studies in the other subbasins are needed to adequately assess the water quality of these areas.

Michigan, Wisconsin↗

USGS1992

Evaluation of agricultural best-management practices in the Conestoga River headwaters, Pennsylvania; description and water quality of the Little Conestoga Creek headwaters prior to the implementation of nutrient management

The headwaters of the Conestoga River are being studied to determine the effects of agricultural Best-Management Practices on surface-water and ground-water quality. As part of this study, a 5.82-square-mile area of the Little Conestoga Creek headwaters (Small Watershed) was monitored during 1984-86, prior to implementation of Best-Management Practices. This report describes the land use and hydrology of this study area and characterizes its surface-water and ground-water quality during the pre-Best-Management Practice phase. During base-flow conditions, median concentrations of dissolved nitrite plus nitrate nitrogen as nitrogen increased from 2.7 to 8.1 milligrams per liter as the stream flowed through the intensively-farmed carbonate valley. Median total phosphorus increased from 0.05 to 0.20 milligram per liter. Concentrations of dissolved nitrate nitrogen as nitrogen measured in ground water in carbonate rocks in the valley were as great as 25 milligrams per liter and consistently exceeded 10 milligrams per liter. Statistical analysis showed that it will require substantial reductions in concentrations and discharges of nitrogen and phosphorus in base flow to obtain statistically measurable improvements in water quality. If concentrations and discharges of total nitrogen in base flow at the five sites are reduced by 15 to 33 percent, and by 63 to 70 percent, respectively, then the Wilcoxon Mann-Whitney rank-sum test will be able to detect an improvement in water quality 95 percent of the time. Likewise, if concentrations of total phosphorus are reduced by 36 to 54 percent, or discharges of total phosphorus are reduced by 52 to 69 percent at the five sites, then an improvement in water quality will be able to be detected 95 percent of the time.

Water-Resources Investigations Report↗

USGS1996

Plan of study to quantify the hydrologic relations between the Rio Grande and the Santa Fe Group aquifer system near Albuquerque, central New Mexico

The Albuquerque Basin in central New Mexico covers an area of about 3,060 square miles. Ground water from the Santa Fe Group aquifer system of the Albuquerque Basin is the principal source of water for municipal, domestic, commercial, and industrial uses in the Albuquerque area, an area of about 410 square miles. Ground- water withdrawal in the basin has increased from about 97,000 acre-feet in 1970 to about 171,000 acre-feet in 1994. About 92 percent of the 1994 total was withdrawn in the Albuquerque area. Management of ground water in the Albuquerque Basin is related to the surface water in the Rio Grande. Because the aquifer system is hydraulically connected to the Rio Grande and water in the river is fully appropriated, the ability to reliably estimate the effects of ground-water withdrawals on flow in the river is important. This report describes the components of the Rio Grande/Santa Fe Group aquifer system in the Albuquerque area and the data availability and data and interpretation needs relating to those components, and presents a plan of study to quantify the hydrologic relations between the Rio Grande and the Santa Fe Group aquifer system. The information needs related to the components of the river/aquifer system are prioritized. Information that is necessary to improve the understanding or quantification of a component in the river/aquifer system is prioritized as essential. Information that could add additional understanding of the system, but would not be necessary to improve the quantification of the system, is prioritized as useful. The study elements are prioritized in the same manner as the information needs; study elements designed to provide information considered necessary to improve the quantification of the system are prioritized as essential, and those designed to provide information that would add additional understanding of the system, but would not be necessary to improve the quantification of the system, are prioritized as useful.

Water-Resources Investigations Report↗

USGS1980

Water quality of Tampa Bay, Florida, June 1972 - May 1976

A comprehensive assessment of the water quality of Tampa Bay, Florida, was initiated in 1970 to provide background information to evaluate the effects of widening and deepening the ship channel to the port of Tampa. This report provides results of water-quality sampling in the bay from 1972 to 1976, prior to dredging. Measurements of temperature, dissolved oxygen, pH, turbidity, specific conductance, biochemical oxygen demand, and total organic carbon were made as well as measurements for several nutrient, metal, and pesticide parameters. Many parameters were measured at as many as three points in the vertical. These data indicate that Tampa Bay is well-mixed vertically with little density stratification. Time histories of average temperature, dissolved oxygen, pH, turbidity, specific conductance and nutrient values within four subareas of Tampa Bay are given to reveal seasonal or other trends during the period of record. Temperature, dissolved oxygen, pH, turbidity, specific conductance, nutrient, biochemical oxygen demand, total organic carbon, and metal data are also presented as areal distributions. Nutrient concentrations were generally higher in Hillsborough Bay than in other sub-areas of Tampa Bay. Biochemical oxygen demand, total organic carbon, and total organic nitrogen distribution patterns show regions of highest concentrations to be along bay shorelines near population centers. Of the metals analyzed, all were present in concentrations of less than 1 milligram per liter. (USGS)

Florida↗

USGS1989

Geohydrology of the Foothill ground-water basin near Santa Barbara, California

Geohydrologic data presented in this report indicate that the East Subbasin of the Goleta groundwater basin and Storage Unit II of the Santa Barbara groundwater basin should be considered as a separate groundwater basin, which is referred to as the Foothill groundwater basin in this report. The 4.5 sq-mi Foothill groundwater basin is bordered on the north and northeast by the Santa Ynez Mountains and on three sides by faults that impede groundwater flow. Sedimentary rocks of Tertiary age underlie the groundwater basin and form its lower boundary. Unconsolidated deposits of the Santa Barbara Formation (Pliocene and Pleistocene age) form the principal aquifer of the basin. Where a zone of low permeability separates it from overlying Quaternary alluvium, the aquifer is confined. In the early 1950's, groundwater levels declined more than 60 ft during periods of heavy pumping. From the mid-1950 's to the late 1970 's, groundwater levels generally rose. Water levels during 1984-87 generally declined. Nitrate concentrations in samples from two wells exceeded the primary maximum contaminant level established by the U.S. Environmental Protection Agency. Secondary maximum contaminant levels for dissolved solids, chloride, and sulfate also were exceeded in some samples. A three-dimensional finite-difference model was developed for part of Foothill groundwater basin. Steady-state verification and transient-state model calibrations were used to estimate or confirm estimates of basin recharge and natural discharge. (USGS)

Water-Resources Investigations Report↗

USGS2000

Analysis of nitrate and volatile organic compound data for ground water in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1980-98

In 1995, ground water was the source of drinking water to about 52 percent of the population served by public drinking water systems in the Great Salt Lake Basins study unit, which includes parts of Utah, Idaho, and Wyoming. Existing nitrate and volatile organic compound data for ground water collected in the study unit were compiled and summarized as part of the National Water-Quality Assessment Program’s objective to describe water-quality conditions in the Nation’s aquifers. Prerequisites for the inclusion of nitrate and volatile organic compound data into this retrospective analysis are that the data set is available in electronic form, the data were collected during 1980-98, the data set is somewhat regional in coverage, and the locations of the sampled sites are known. Ground-water data stored in the U.S. Geological Survey’s National Water Information System and the Idaho and Utah Public Drinking Water Systems databases were reviewed. Only the most recent analysis was included in the data sets if more than one analysis was available for a site. The National Water Information System data set contained nitrate analyses for water from 480 wells. The median concentration of nitrate was 1.30 milligrams per liter for the 388 values above minimum reporting limits. The maximum contaminant level for nitrate as established by the U.S. Environmental Protection Agency was exceeded in water from 10 of the 200 wells less than or equal to 150 feet deep and in water from 3 of 280 wells greater than 150 feet deep. The Public Drinking Water Systems data set contained nitrate analyses for water from 587 wells. The median concentration of nitrate was 1.12 milligrams per liter for the 548 values above minimum reporting limits. The maximum contaminant level for nitrate was exceeded at 1 site and 22 sites had concentrations equal to or greater than 5 milligrams per liter. The types of land use surrounding a well and the well depth were related to measured nitrate concentrations in the sampled ground water. Overall, water sampled from wells in rangeland areas had a lower median measured nitrate concentration (0.76 milligrams per liter) than water from areas with an agricultural or urban/residential land use (1.41 and 1.20 milligrams per liter, respectively). In the National Water Information System data set, the median measured nitrate concentration in water from urban/residential areas varied from 1.00 milligrams per liter for wells greater than 150 feet deep to 1.84 milligrams per liter for wells less than or equal to 150 feet deep. The Public Drinking Water Systems and the National Water Information System data sets contained analyses for most of the State and Federally regulated volatile organic compounds in water from about 368 and 74 wells, respectively. Fifteen different volatile organic compounds were detected at least once in ground water sampled from the Great Salt Lake Basins study unit. Water from 21 wells contained at least 1 volatile organic compound at detectable concentrations. About 68 percent of the volatile organic compounds detected were in water sampled from wells in Salt Lake County, Utah. Tetrachloroethylene was the most commonly detected volatile organic compound in ground water sampled from the study unit, present in 8 out of 442 samples. Maximum contaminant levels for tetrachloroethylene and 1,1-dichloroethylene as established by the U.S. Environmental Protection Agency were exceeded in water from one well each.

Idaho,Utah, Wyoming↗

USGS1991

Geologic setting and water quality of selected basins in the active coal-mining areas of Ohio, 1987-88

This report presents hydrologic data from selected drainage basins in the active coal-mining areas of Ohio from July 1987 through October 1988. The study area is mostly within the unglaciated part of eastern Ohio along the western edge of the Appalachian Plateaus physiographic province. The 1987-88 work is the second phase of a 7-year study to assess baseline water quality in Ohio's coal region. The data collection network consisted of 41 long-term surface-water sites in 21 basins. The sites were measured and sampled twice yearly at low flow. In addition, six individual basins (three each year) selected for a more detailed representation of surface-water and ground-water quality. In 1987, the Sandy Creek, Middle Tuscarawas River and Sugar Creek, and Lower Tuscarawas River basins were chosen. In 1988, the Short and Wheeling Creeks, Upper Wills Creek, and Upper Raccoon Creek basins were chosen. Because of their proximity to the glaciated region and outwash drainage, the basins studied intensively in 1987 contain more shallow productive aquifers than do the basins studied in detail for 1988, in which shallow ground-water sources are very localized. Chemical analyses for 202 surface-water and 24 ground-water samples are presented. For field measurements made at surface-water sites, the specific conductance ranged from 295 to 3150 ? S/cm (microsiemens per centimeter at 25 degrees Celsius). For pH, the range was 2.8 to 8.6. Alkalinity ranged from 5 to 305 mg/L (milligrams per liter) as CaCO3.

Water-Resources Investigations Report↗

USGS2001

Low-flow characteristics of streams in Ohio through water year 1997

This report presents selected low-flow and flow-duration characteristics for 386 sites throughout Ohio. These sites include 195 long-term continuous- record stations with streamflow data through water year 1997 (October 1 to September 30) and for 191 low-flow partial-record stations with measurements into water year 1999. The characteristics presented for the long-term continuous-record stations are minimum daily streamflow; average daily streamflow; harmonic mean flow; 1-, 7-, 30-, and 90-day minimum average low flow with 2-, 5-, 10-, 20-, and 50-year recurrence intervals; and 98-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, 50-, 40-, 30-, 20-, and 10-percent daily duration flows. The characteristics presented for the low-flow partial-record stations are minimum observed streamflow; estimated 1-, 7-, 30-, and 90-day minimum average low flow with 2-, 10-, and 20-year recurrence intervals; and estimated 98-, 95-, 90-, 85- and 80-percent daily duration flows. The low-flow frequency and duration analyses were done for three seasonal periods (warm weather, May 1 to November 30; winter, December 1 to February 28/29; and autumn, September 1 to November 30), plus the annual period based on the climatic year (April 1 to March 31).

Ohio↗

USGS1996

Sampling design for assessing water quality of the Red River of the North basin, Minnesota, North Dakota, and South Dakota, 1993-1995

This map report describes the sampling design for a comprehensive regional assessment of water quality in the Red River of the North Basin, a study unit under the U.S. Geological Survey’s National Water-Quality Assessment Program. The sampling design was developed to address questions about the presence, distribution, and loads of nutrients and pesticides associated with large agricultural regions in the basin and across the Nation. The design also begins to address major local and regional concerns about suspended sediment in surface water and naturally occurring salinity in ground water. Recognizing that the Red River of the North Basin study unit realistically could not be analyzed as a single homogeneous area, a hierarchical sampling stratification for assessing water quality was developed. Landscape features consisting of physiography, soils, land cover and land use, and cropping patterns provided the environmental framework for stratification of streams and surficial aquifers. The environmental framework characterizes the climate and hydrology and relates closely to an ecoregions framework. The environmental and ecoregions frameworks were considered in locating ecological sampling sites. For the subsurface framework, buried sand and gravel aquifers in study unit were subdivided into two general subregions of differing potential saline recharge from underlying bedrock aquifers. Actual sampling sites for streams, aquatic biology, and ground water were described within the proposed sampling stratification. Practical considerations of previously established sampling sites, background information from previous hydrologic investigations, and site suitability for sampling protocols also were considered for final site selection.

Minnesota, North Dakota, South Dakota↗

USGS1969

Selected hydrologic data, southern Utah and Goshen Valleys, Utah

The purpose of this report is to present basic geologic, ground-water, surface-water, and quality of water data that are useful for the study and effective development of the water resources of southern Utah and Goshen Valleys. This report supplements an interpretive report which will be published later. Much of the basic data was collected by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, during the years 1935-67. Data collected by other organizations are also included in this report.

Utah↗

USGS1990

Computerized stratified random site-selection approaches for design of a ground-water-quality sampling network

Computer software was written to randomly select sites for a ground-water-quality sampling network. The software uses digital cartographic techniques and subroutines from a proprietary geographic information system. The report presents the approaches, computer software, and sample applications. It is often desirable to collect ground-water-quality samples from various areas in a study region that have different values of a spatial characteristic, such as land-use or hydrogeologic setting. A stratified network can be used for testing hypotheses about relations between spatial characteristics and water quality, or for calculating statistical descriptions of water-quality data that account for variations that correspond to the spatial characteristic. In the software described, a study region is subdivided into areal subsets that have a common spatial characteristic to stratify the population into several categories from which sampling sites are selected. Different numbers of sites may be selected from each category of areal subsets. A population of potential sampling sites may be defined by either specifying a fixed population of existing sites, or by preparing an equally spaced population of potential sites. In either case, each site is identified with a single category, depending on the value of the spatial characteristic of the areal subset in which the site is located. Sites are selected from one category at a time. One of two approaches may be used to select sites. Sites may be selected randomly, or the areal subsets in the category can be grouped into cells and sites selected randomly from each cell.

Water-Resources Investigations Report↗

USGS1995

Computation of bedrock-aquifer recharge in northern Westchester County, New York, and chemical quality of water from selected bedrock wells

An empirical technique was used to calculate the recharge to bedrock aquifers in northern Westchester County. This method requires delineation of ground-water divides within the aquifer area and values for (1) the extent of till and exposed bedrock within the aquifer area, and (2) mean annual runoff. This report contains maps and data needed for calculation of recharge in any given area within the 165square-mile study area. Recharge was computed by this technique for a 93-square-mile part of the study area and used a ground-water-flow model to evaluate the reliability of the method. A two-layer, steady-state model of the selected area was calibrated. The area consists predominantly of bedrock overlain by small localized deposits of till and stratified drill Ground-water-level and streamflow data collected in mid-November 1987 were used for model calibration. The data set approximates average annual conditions. The model was calibrated from (1) estimates of recharge as computed through the empirical technique, and (2) a range of values for hydrologic properties derived from aquifer tests and published literature. Recharge values used for model simulation appear to be reasonable for average steady-state conditions. Water-quality data were collected from 53 selected bedrock wells throughout northern Westchester County to define the background ground-water quality. The constituents and properties for which samples were analyzed included major cations and anions, temperature, pH, specific conductance, and hardness. Results indicate little difference in water quality among the bedrock aquifers within the study area. Ground water is mainly the calcium-bicarbonate type and is moderately hard. Average concentrations of sodium, sulfate, chloride, nitrate, iron, and manganese were within acceptable limits established by the U.S. Environmental Protection Agency for domestic water supply.

Water-Resources Investigations Report↗