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Water-quality assessment of the Rio Grande Valley, Colorado, New Mexico, and Texas: Shallow ground-water quality of a land-use area in the San Luis Valley, south-central Colorado, 1993

This report describes the quality of shallow ground water in an agricultural area in the San Luis Valley, Colorado, and discusses how natural and human factors affect the quality of shallow ground water. Thirty-five wells were installed, and water samples were collected from these wells and analyzed for selected dissolved common constituents, nutrients, trace elements, radionuclides, and synthetic organic compounds. The San Luis Valley is a high intermontane valley that is partially drained by the Rio Grande. The San Luis Valley land-use study area was limited to a part of the valley where the depth to water is generally less than 25 feet. The area where the 35 monitor wells were installed was further limited to the part of the study area where center-pivot overhead sprinklers are used to irrigate crops. Precipitation, runoff from adjacent mountainous areas, and ground-water inflow from the adjacent mountainous areas are the main sources of water to the aquifers in the San Luis Valley. Discharge of water from the shallow, unconfined aquifer in the valley is mainly from evapotranspiration. The dominant land use in the San Luis Valley is agriculture, although nonirrigated land and residential land are interspersed with agricultural land. Alfalfa, native hay, barley, wheat, potatoes, and other vegetables are the main crops. Dissolved-solids concentrations in shallow ground water sampled ranged from 75 to 1,960 milligrams per liter. The largest median concentration of cations was for calcium, and the largest median concentration of anions was for bicarbonate in shallow ground water in the San Luis Valley. Calcium concentrations ranged from 7.5 to 300 milligrams per liter, and bicarbonate concentrations ranged from 28 to 451 milligrams per liter. Nitrite plus nitrate concentrations ranged from less than 0.1 to 58 milligrams per liter as N; water from 11 wells had nitrite plus nitrate concentrations greater than 10 milligrams per liter as N. With the exception of the following trace elements--aluminum, barium, iron, manganese, molybdenum, and uranium--the concentrations of trace elements were less than 10 micrograms per liter in 90 percent of the samples. All trace-element concentrations measured were below the maximum contaminant levels set by the U.S. Environmental Protection Agency. Five samples exceeded the proposed maximum contaminant level of 0.02 milligram per liter for uranium. All samples collected exceeded the proposed maximum contaminant level for radon-222. The volatile organic compound methyltertbutylether was detected in one sample at a concentration of 0.6 microgram per liter. Of the pesticides analyzed for, one or more were detected in water from 5 of the 35 wells sampled. Metribuzin was the most commonly detected pesticide and was detected in water from three wells at concentrations ranging from an estimated 0.005 to 0.017 microgram per liter. Metolachlor (detected in one sample at a concentration of 0.072 microgram per liter), prometon (detected in one sample at a concentration of 0.01 microgram per liter), and p,p'-DDE (detected in one sample at an estimated concentration of 0.002 microgram per liter) were the other pesticides detected. The U.S. Environmental Protection Agency lifetime health advisory for metolachlor, metribuzin, and prometon is 100 micrograms per liter, which is much larger than the concentrations measured in the shallow ground water sampled for this study. The elevated nitrite plus nitrate concentrations in shallow ground water are indicative of leaching of fertilizers from the land surface. This conclusion is consistent with conclusions made in other investigations of the San Luis Valley.

Colorado↗

Reconnaissance of geology and ground water in the lower Grand River valley, South Dakota, with a section on Chemical quality of the ground water

The area described in this report is the flood plain of the Grand River and the bordering benchlands in Perkins and Corson Counties, S. Dak., from a point about 6 miles west of the town of Shadehill to the confluence of the Grand and Missouri Rivers near Mobridge. The exposed bedrock formations include the Pierre shale, the Fox Hills sandstone, and the Hell Creek formation of Late Cretaceous age, and-the Ludlow member of the Fort Union formation of Tertiary (Paleocene) age. Some stringers of the Cannonball formation probably interfinger with beds of the Ludlow member but none of the former was identified during the field investigations. The Pierre shale is exposed from the mouth of the Grand River to approximately the center of the area. Although a few wells in the area obtain water from this formation, it is not generally considered to be a source of supply. The Fox Hills sandstone, the Hell Creek formation, and the Ludlow member of the Fort Union formation are exposed successively upstream and, where saturated, yield small to moderate quantities of water to wells. Unconsolidated deposits of silt, sand, and gravel occur in several physiographic positions; they underlie the high benchland on both sides of the river, the poorly defined terraces along the river, and the flood plain throughout its entire length. Possibly all these unconsolidated deposits are water bearing; however, where the deposits on the benchland and in the terraces are dissected by streams, they probably contain little or no water. The average depth to ground water along the lower Grand River valley is about 17 feet. Probably, the flow of ground water in the bottom lands is nearly parallel to and slightly toward the surface stream. The measurements of the water level in observation wells for the period 1946-48 indicate that the fluctuations of the water table are small. The results of analyses of 13 samples of ground water from the alluvium and the Hell Creek formation show that the suitability of the ground water for use varies because of the considerable range in mineralization and composition. Dissolved solids ranged from 343 to 4,250 parts per million (ppm), hardness from 11 to 1,130 ppm, and percentage of sodium from 25 to 98. Concentrations of some of the individual constituents exceed standards of the United States Public Health Service. The water is moderately hard and contains undesirable amounts of iron and moderate to large amounts of dissolved solids. In general, the water quality ranges from excellent to unsuitable for irrigation use. The result of the mixing of the ground water with recharge water from Shadehill Reservoir cannot be predicted on the basis of available data. The geologic and hydrologic data in this report were obtained from earlier reports and from field observations during the period 1946-48. The report includes a geologic map and tabulated well records.

South Dakota↗

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↗

Records of wells, water levels, and chemical quality of ground water in the French Prairie-Mission Bottom area, northern Willamette Valley, Oregon

An investigation of the ground-water resources of the northern Willamette Valley was begun in 1960 as a cooperative program between the Ground Water Branch, U.S. Geological Survey, and the Oregon State Engineer. The northern Willamette Valley area is one of the fastest growing areas of ground-water use within the state. The purpose of the investigation is to obtain an understanding of the availability, movement, and chemical quality of the ground-water resources of the area. This information is needed to attain an optimum development of the ground-water resources of the area and to aid in the prevention of problems of overdevelopment and pollution. The first phase of the program was the collection of well records, water level records, and chemical quality data in the central part of this area, which is known as the French Prairie-Mission Bottom area. The records collected in this phase of the study are essential in the preparation of an interpretive report describing the occurrence and movement of ground-water in the French Prairie-Mission Bottom area. These records, which will not be included in the interpretive report that is being prepared at this time, are being made available in this publication to aid in the location and the development of the ground-water resources of the area, and to serve as a supplement to the forthcoming interpretive report.

Oregon↗

Water resources data, Nebraska, water year 2004

The Nebraska water resources data report for water year 2004 includes records of stage, discharge, and water quality of streams; water elevation and/or contents of lakes and reservoirs; and water levels and quality of ground water in wells. This report contains records of stream stage for 3 stations; stream discharge for 101 continuous and 5 crest-stage gaging stations, and 6 miscellaneous sites; stream water quality for 7 gaging stations and 40 miscellaneous sites; water elevation and/or contents for 2 lakes and 1 reservoir; ground-water levels for 74 observation wells; and ground-water quality for 200 wells. These data represent that part of the National Water Data System collected in and near Nebraska by the U.S. Geological Survey and cooperating Federal, State, and local agencies.

Water Data Report↗

An appraisal of the ground-water resources of the Juniata River Basin, Pennsylvania

This report describes the availability, quantity, quality, variability, and cost of development of the ground-water resources in the Juniata River basin, one of the larger sub-basins of the Susquehanna River basin. The report has been prepared for and under specifications established by the Corps of Engineers, U. S. Army, and the Public Health Service, Department of Health, Education, and Welfare. A comprehensive study of the water and related land resources of the Susquehanna River basin was authorized by the Congress of the United States in October 1961, and the task of preparing a report and of coordinating the work being done by others in support of the study was assigned to the Corps of Engineers. The comprehensive study is being conducted by several Federal departments and independent agencies in cooperation with the States of New York, Pennsylvania, and Maryland. The Public Health Service under its authority in the Federal Water Pollution Control Act (P. L. 660) initiated a comprehensive water quality control program for the Chesapeake drainage basin, which includes the Susquehanna River basin.

Pennsylvania↗

Selected hydrologic data for the Mesilla ground-water basin, 1987 through 1992 water years, Doña Ana County, New Mexico, and El Paso County, Texas

The Mesilla ground-water basin monitoring program was established in 1987 to document hydrologic conditions and establish a long-term, continuous data base to permit future quantitative evaluation of the ground-water flow system and stream/aquifer relations. Data collection is divided into three program elements. These are the (1) Mesilla ground- water basin observation-well program; (2) Mesilla Valley hydrologic sections; and (3) Rio Grande seepage investigations. This report is a compilation of hydrologic data collected for the Mesilla ground- water basin monitoring program during the 1987 through 1992 water years. Hydrologic data presented in the report include well records and water levels for 181 wells; mean daily river stage and ground- water levels at 37 sites; seepage investigations of the Rio Grande from Radium Springs, New Mexico, to El Paso, Texas; and chemical analyses of 29 water samples collected from the Rio Grande.

New Mexico, Texas↗

Generalized estimates from streamflow data of annual and seasonal ground-water-recharge rates for drainage basins in New Hampshire

This report presents regression equations to estimate generalized annual and seasonal ground-water-recharge rates in drainage basins in New Hampshire. The ultimate source of water for a ground-water withdrawal is aquifer recharge from a combination of precipitation on the aquifer, ground-water flow from upland basin areas, and infiltration from streambeds to the aquifer. An assessment of ground-water availability in a basin requires that recharge rates be estimated under `normal' conditions and under assumed drought conditions. Recharge equations were developed by analyzing streamflow, basin characteristics, and precipitation at 55 unregulated continuous record stream-gaging stations in New Hampshire and in adjacent states. In the initial step, streamflow records were analyzed to estimate a series of annual and seasonal ground-water-recharge components of streamflow in each drainage basin evaluated in this study. Regression equations were then developed relating the series of annual and seasonal ground-water-recharge values to the corresponding series of annual and seasonal precipitation values as determined at the centroid of each drainage basin. This resulted in one equation for each of the 55 basins for each of the four seasonal periods and the annual period, or a total of 275 regression equations. Average annual and seasonal precipitation data for 1961-90 were then used to compute a set of normalized ground-water-recharge values that reflected the long-term average annual and seasonal variations (normalized) and mean recharge characteristics of each drainage basin. Ordinary-least-squares regression was applied in the process of selecting 10 out of 93 possible basin and climatic characteristics for further testing in the development of the equations for computing the generalized estimate of annual and seasonal ground-water recharge based on the set of normalized recharge values. Generalized-least-squares regression was used for the final parameter estimation and error evaluation. The following basin and climatic characteristics were found to be statistically significant predictors for at least one of the dependent variables: average annual, summer, and spring precipitation as determined at U.S. Geological Survey stream-gaging stations; average annual basin-centroid precipitation; average mean annual basin temperature; average minimum winter basin temperature; percent coniferous forest in a basin; percent mixed coniferous and deciduous forest in a basin; average fall basin-centroid precipitation; and average annual snowcover. These 10 basin and climatic characteristics were selected because they were statistically significant based on several statistical parameters that evaluated which combination of characteristics contributed the most to the predictive accuracy of the regression-equation models. A geographic information system is required to measure the values of the predictor variables for the equations developed in the study. The average annual normalized ground-water recharge was 21.0 in. This value was determined by generalized-least-squares (GLS) regression analysis for all of the basins used in the normalized ground-water recharge analysis for precipitation from 1961-90. The average winter (January 1-March 15) ground-water recharge was 4.3 in., average spring (March 16-May 31) ground-water recharge was 9.0 in., average summer (June 1-October 31) ground-water recharge was 4.0 in., and average fall (November 1-December 31) ground-water recharge was 3.6 in. Normalized ground-water recharge ranged annually from 12.3 to 31.8 in., for winter from 2.30 to 7.82 in., for spring from 5.16 to 13.7 in., for summer from 1.45 to 10.2 in., and for fall from 2.21 to 6.06 in.

New Hampshire↗

Water resources data, Wyoming, water year 1997: Volume 2. Ground water

Water resources data for the 1997 water year for Wyoming consists of records of stage, discharge and water quality of streams; stage and contents of lakes and reservoirs, and water levels and water quality of ground water. Volume 2 of this report contains water levels records for 82 wells. Additional ground-water data were collected at various sites, not part of the systematic data collection program, and are published as miscellaneous studies and programs. These data together with the data in Volume 1 represent part of the National Water Data System operated by theU.S. Geological Survey and cooperating State and Federal agencies in Wyoming.

Wyoming↗

Water resources data, Wyoming, water year 1998: Volume 2. Ground water

Water resources data for the 1998 water year for Wyoming consists of records of stage, discharge and water quality of streams; stage and contents of lakes and reservoirs, and water levels and water quality of ground water. Volume 2 of this report contains water levels records for 73 wells. Additional ground-water data were collected at various sites, not part of the systematic data collection program, and are published as miscellaneous studies and programs. These data together with the data in Volume 1 represent part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Wyoming.

Wyoming↗

Private Domestic-Well Characteristics and the Distribution of Domestic Withdrawals among Aquifers in the Virginia Coastal Plain

A comprehensive analysis of private domestic wells and self-supplied domestic ground-water withdrawals in the Coastal Plain Physiographic Province of Virginia indicates that the magnitudes of these withdrawals and their effects on local and regional ground-water flow are larger and more important than previous reports have stated. Self-supplied ground-water withdrawals for domestic use in the Virginia Coastal Plain are estimated to be approximately 40 million gallons per day, or about 28 percent of all ground-water withdrawals in the area. Contrary to widely held assumptions, only 22 percent of domestic wells in the Virginia Coastal Plain are completed in the shallow, unconfined surficial aquifer to which the water is returned directly by home septic systems. Fifty-three percent of the wells are completed in six deeper confined aquifers, and the remaining 25 percent are completed in the Potomac aquifer and confining zone, the deepest units in the confined system. Assuming an equal rate of withdrawal per well, 78 percent of domestic ground-water withdrawal, or about 30 million gallons per day, is removed from the regional confined ground-water system. Domestic ground-water withdrawal from an estimated 200,000 private wells supplies more than 15 percent of the population of the area and provides almost the entire source of water in some rural counties. The geographic distribution of these withdrawals is dependent on the self-supplied population and is highly variable. Domestic-well characteristics vary spatially as well, primarily because of geographic differences in depths to particular aquifers, but also because of well-drilling practices that are influenced by geographic, regulatory, and socioeconomic factors. Domestic ground-water withdrawals in the Virginia Coastal Plain were characterized as part of a larger study to analyze the regional ground-water flow system. Characterizing the withdrawals required differentiation of the withdrawals among the aquifers in the area in addition to determination of the geographic distribution of the withdrawals. Because of a lack of comprehensive data on private-well construction and distribution, a sample of private domestic-well records was used to estimate well characteristics and approximate the proportion of wells and withdrawals associated with each aquifer. Construction data on 2,846 private domestic wells were collected from 29 counties and independent cities (localities) having appreciable self-supplied populations and representing private domestic withdrawals of about 31 million gallons per day. Within each locality, geographically stratified random sampling of well records by tax plat characterized details of well construction for the population of domestic wells. Because neither specific location data nor aquifer elevations were available for individual wells, the primary aquifer in which each well is completed was estimated by cross-referencing the screen elevation estimated from the well record with a generalized configuration of hydrogeologic units underlying the locality in which the well is located. For each locality, summarizing the results of this process allowed the determination of the proportion of wells and withdrawals associated with each aquifer. Additional evaluation of spatial data was used to apply the domestic withdrawal rates developed for each aquifer in each locality to a detailed ground-water study of the portion of the Virginia Coastal Plain east of the Chesapeake Bay, which is known as the Eastern Shore Peninsula. Because domestic withdrawal estimates are based on the self-supplied population, the geographic distribution of withdrawals within each of the Eastern Shore counties was estimated by using population data from the 2000 U.S. Census at the resolution of census block groups and further refining the distribution based on road density. The allocation of withdrawals among aquifers was then determined by cross-referencing the spatial distribut

Scientific Investigations Report↗

A progress report on results of test drilling and ground-water investigations of the Snake Plain aquifer, southeastern Idaho: Part 1: Mud Lake Region, 1969-70 and Part 2: Observation Wells South of Arco and West of Aberdeen

The results of drilling test holes to depths of approximately 1,000 feet in the Mud Lake region show that a large part of the region is underlain by both sedimentary deposits and basalt flows. At some locations, predominantly sedimentary deposits were penetrated; at others, basalt flows predominated. The so-called Mud Lake-Market Lake barrier denotes a change in geology. From the vicinity of the barrier area, as described by Stearns, Crandall, and Steward (1938, p. 111), up the water-table gradient for at least a few tens of miles, the saturated geologic section consists predominantly of beds of sediments that are intercalated with numerous basalt flows. Downgradient from the barrier, sedimentary deposits are not common and practically all the water-bearing formations are basalt, at least to the depths explored so far. Thus, the barrier is a transition zone from a sedimentary-basaltic sequence to a basaltic sequence. The sedimentary-basaltic sequence forms a complex hydrologic system in which water occurs under water-table conditions in the upper few tens of feet of saturated material and under artesian conditions in the deeper material in the southwest part of the region. The well data indicate that southwest of the barrier, artesian pressures are not significant. Southwest of the barrier, few sedimentary deposits occur in the basalt section and, as described by Mundorff, Crosthwaite, and Kilburn (1964). ground water occurs in a manner typical of the Snake Plain aquifer. In several wells, artesian pressures are higher in the deeper formations than in the shallower ones, but the reverse was found in a few wells. The available data are not adequate to describe the water-bearing characteristics of the artesian aquifer nor the effects that pumping in one zone would have on adjacent zones. The water-table aquifer yields large quantities of water to irrigation wells.

Idaho↗

Ground-water conditions in the Dutch Flats area, Scotts Bluff and Sioux Counties, Nebraska, with a section on chemical quality of the ground water

The U.S. Department of the Interior (DOI) studied contamination induced by irrigation drainage in 26 areas of the Western United States during 1986-95. Comprehensive compilation, synthesis, and evaluation of the data resulting from these studies were initiated by DOI in 1992. Soils and ground water in irrigated areas of the West can contain high concentrations of selenium because of (1) residual selenium from the soil's parent rock beneath irrigated land; (2) selenium derived from rocks in mountains upland from irrigated land by erosion and transport along local drainages, and (3) selenium brought into the area in surface water imported for irrigation. Application of irrigation water to seleniferous soils can dissolve and mobilize selenium and create hydraulic gradients that cause the discharge of seleniferous ground water into irrigation drains. Given a source of selenium, the magnitude of selenium contamination in drainage-affected aquatic ecosystems is strongly related to the aridity of the area and the presence of terminal lakes and ponds. Marine sedimentary rocks and deposits of Late Cretaceous or Tertiary age are generally seleniferous in the Western United States. Depending on their origin and history, some Tertiary continental sedimentary deposits also are seleniferous. Irrigation of areas associated with these rocks and deposits can result in concentrations of selenium in water that exceed criteria for the protection of freshwater aquatic life. Geologic and climatic data for the Western United States were evaluated and incorporated into a geographic information system (GIS) to produce a map identifying areas susceptible to irrigation-induced selenium contamination. Land is considered susceptible where a geologic source of selenium is in or near the area and where the evaporation rate is more than 2.5 times the precipitation rate. In the Western United States, about 160,000 square miles of land, which includes about 4,100 square miles (2.6 million acres) of land irrigated for agriculture, has been identified as being susceptible. Biological data were used to evaluate the reliability of the map. In 12 of DOI's 26 study areas, concentrations of selenium measured in bird eggs were elevated sufficiently to significantly reduce hatchability of the eggs. The GIS map identifies 9 of those 12 areas. Deformed bird embryos having classic symptoms of selenium toxicosis were found in four of the study areas, and the map identifies all four as susceptible to irrigation-induced selenium contamination. The report describes the geography, geology, and ground-water resources of the Dutch Flats area in Scotts Bluff and Sioux Counties, Nebr. The area comprises about 60 square miles and consists predominantly of relatively flat-lying terraces. Farming is the principal occupation in the area. The farm lands are irrigated largely from surface water; ground water is used only as a supplementary supply during drought periods. The climate in the area is semiarid, and the mean annual precipitation is about 16 inches. The rocks exposed in the Dutch Flats area are of Tertiary sad Quaternary age. A map showing the areas of outcrop of the rock formations is included in the report. Sufficient unconfined ground water for irrigation supplies is contained in the deposits of the .third terrace, and wells that yield 1,000 to 2,000 gallons a minute probably could be developed. The depth to water in the area ranges from a few feet to about 80 feet sad averages about 30 feet. The depth to water varies throughout the year; it is least in the late summer when the recharge from irrigation is greatest, sad it is greatest in the early spring before irrigation is begun. A map showing the depth to water in September 1949 is included in the report. The ground-water reservoir is recharged by seepage from irrigation canals and laterals, by seepage from irrigation water applied to the farms, and, to a much lesser extent, by precipitation. In the area b

Nebraska↗

Hypothetical modeling of redox conditions within a complex ground-water flow field in a glacial setting

This report describes a modeling approach for studying how redox conditions evolve under the influence of a complex ground-water flow field. The distribution of redox conditions within a flow system is of interest because of the intrinsic susceptibility of an aquifer to redox-sensitive, naturally occurring contaminants - such as arsenic - as well as anthropogenic contaminants - such as chlorinated solvents. The MODFLOW-MT3D-RT3D suite of code was applied to a glacial valley-fill aquifer to demonstrate a method for testing the interaction of flow patterns, sources of reactive organic carbon, and availability of electron acceptors in controlling redox conditions. Modeling results show how three hypothetical distributions of organic carbon influence the development of redox conditions in a water-supply aquifer. The distribution of strongly reduced water depends on the balance between the rate of redox reactions and the capability of different parts of the flow system to transmit oxygenated water. The method can take account of changes in the flow system induced by pumping that result in a new distribution of reduced water.

Scientific Investigations Report↗

Water levels in observation wells in Santa Barbara County, California, in 1961

Investigation of the ground-water resources of Santa Barbara County was continued during 1961 by the U. S. Geological Survey in cooperation with the Santa Barbara County Water Agency. Monthly water-level measurements were made in 190 wells, in 9 of which automatic water-level recorders were operated. Earlier measurements, covering the period 1941 through 1955, have been published in U. S. Geological Survey Water-Supply Papers (1943-1957); those for 1956 through 1960 have been released locally in duplicated form (Muir and Merritt, 1957; Evenson, 1958; Miller, 1959; Muir, Merritt, and Miller, 1960; and Merritt, 1961). LaRocque, Jr., and others (1950) contains tabulated descriptions of 2,246 wells in existence in 1942 in the several ground-water basins of the county. The same publication also contains many water-level measurements made prior to 1942 by the city of Santa Barbara, Santa Maria Valley Water Conservation District, San Joaquin Power Division of the Pacific Gas and Electric Co., Union Sugar Co., Union Oil Co., and other organizations and individuals. Comprehensive reports on the geology and ground-water resources of the Santa Ynez River basin (Upson and Thomasson, 1951, and Wilson, 1959), the south-coast basins (Upson, 1951), the Santa Maria Valley area (Worts, 1951), and the Cuyama Valley (Upson and Worts, 1951) have been published as Water-Supply Papers 1107, 1467, 1108, 1000, and 1110-B, respectively. A similar report on the San Antonio Creek Valley is in preparation. A report on stream runoff and ground-water storage capacity of the Santa Ynez River valley (Troxell and Wilson, 1952) was released to the open file on October 1952. In addition to the water-level measurements made by the Geological Survey in 1961, measurements made by the Santa Maria Valley Water Conservation District are included in this report. Not included in this report are miscellaneous measurements made by the U. S. Bureau of Reclamation in wells along the middle reach of the Santa Ynez River between Cachuma Dam and Rucker Crossing.

California↗

Surface-Water and Ground-Water Resources of Kendall County, Illinois

Water-supply needs in Kendall County, in northern Illinois, are met exclusively from ground water derived from glacial drift aquifers and bedrock aquifers open to Silurian, Ordovician, and Cambrian System units. As a result of population growth in Kendall County and the surrounding area, water use has increased from about 1.2 million gallons per day in 1957 to more than 5 million gallons per day in 2000. The purpose of this report is to characterize the surface-water and ground-water resources of Kendall County. The report presents a compilation of available information on geology, surface-water and ground-water hydrology, water quality, and water use. The Fox River is the primary surface-water body in Kendall County and is used for both wastewater disposal and as a drinking-water supply upstream of the county. Water from the Fox River requires pretreatment for use as drinking water, but the river is a potentially viable additional source of water for the county. Glacial drift aquifers capable of yielding sufficient water for municipal supply are expected to be present in northern Kendall County, along the Fox River, and in the Newark Valley and its tributaries. Glacial drift aquifers capable of yielding sufficient water for residential supply are present in most of the county, with the exception of the southeastern portion. Volatile organic compounds and select trace metals and pesticides have been detected at low concentrations in glacial drift aquifers near waste-disposal sites. Agricultural-related constituents have been detected infrequently in glacial drift aquifers near agricultural areas. However, on the basis of the available data, widespread, consistent problems with water quality are not apparent in these aquifers. These aquifers are a viable source for additional water supply, but would require further characterization prior to full development. The shallow bedrock aquifer is composed of the sandstone units of the Ancell Group, the Prairie du Chien Group, the Galena-Platteville dolomite, the Maquoketa Group, and the Silurian dolomite where these units are at the bedrock surface. The availability of water from the shallow bedrock aquifer depends primarily on the geologic unit utilized. The Silurian dolomite, Galena-Platteville dolomite, and Ancell Group can yield sufficient water for residential and municipal supply in at least some parts of the county. The Cambrian-Ordovician aquifer system is composed of the most widespread, productive aquifers in northern Illinois and is used for water supply by a number of municipalities and industrial facilities. Water levels in the aquifer system have declined by as much as 600 feet in Kendall County and the aquifer frequently contains concentrations of radium above established health guidelines.

Scientific Investigations Report↗

Hydrogeologic data for the Blaine aquifer and associated units in southwestern Oklahoma and northwestern Texas

This report is a compilation of hydrogeologic data collected for an areal ground-water investigation of the Blaine aquifer and associated units in southwestern Oklahoma and northwestern Texas. The study area includes parts of Greer, Harmon, and Jackson counties in Oklahoma and parts of Childress, Collingsworth, Hall, Hardeman, and Wilbarger counties in Texas. The Blaine aquifer consists of cavernous gypsum and dolomite beds. Water from the Blaine aquifer supports a local agriculture based mainly on irrigated cotton and wheat. The purpose of the study was to determine the availability, quantity, and quality of ground water from the Blaine aquifer and associated units. This report provides a reference for some of the data that was used as input into a computer ground-water flow model that simulates ground-water flow in the Blaine aquifer. The data in this report consists of: (1) Monthly or periodic water-level measurements in 134 wells; (2) daily mean water-level measurements for 11 wells equipped with water-level recorders; (3) daily total precipitation measurements from five precipitation gages; (4) low-flow stream-discharge measurements for 89 stream sites; (5) miscellaneous stream-discharge measurements at seven stream sites; (6) chemical analyses of surface water from 78 stream sites during low-flow periods; (7) chemical analyses of ground water from 41 wells; and (8) chemical analyses of runoff water collected at five sites.

Open-File Report↗