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Simulation of ground-water flow in the St Peter aquifer in an area contaminated by coal-tar derivatives, St Louis Park, Minnesota

A model constructed to simulate ground-water flow in part of the Prairie du Chien-Jordan and St. Peter aquifers, St. Louis Park, Minnesota, was used to test hypotheses about the movement of ground water contaminated with coal-tar derivatives and to simulate alternatives for reducing the downgradient movement of contamination in the St. Peter aquifer. The model, constructed for a previous study, was applied to simulate the effects of current ground-water withdrawals on the potentiometric surface of the St. Peter aquifer. Multiaquifer wells served as conduits for vertical exchange of water from the St. Peter aquifer to the Prairie du Chien-Jordan aquifer. Model simulations predict that the multiaquifer wells have the potential to limit downgradient migration of contaminants in the St. Peter aquifer caused by cones of depression created around the multiaquifer wells. Differences in vertical leakage to the St. Peter aquifer may exist in areas of bedrock valleys. Model simulations indicate that these differences are not likely to affect significantly the general patterns of ground-water flow. Model simulations also indicated that drawdown caused by pumping two wells, each pumping at 75 gallons per minute and located about 1 mile southeast of the source of contamination, would be effective in controlling movement and volume of contaminated ground water in the immediate area of the source of contamination. Some contamination may already have moved beyond the influence of these wells, however, because of a complex set of hydraulic conditions.

Minnesota↗

Ground-water withdrawals and changes in water levels in the Houston District, Texas

During 1975-79, total withdrawals of ground water in the Houston district decreased by 9.7 percent. This percentage represents a decrease from 505 million gallons per day (22.1 cubic meters per second) during 1975, to 456 million gallons per day (20.0 cubic meters per second) during 1979. The decrease resulted from an increased use of surface water that became available from Lake Livingston on the Trinity River during late 1976. During 1975-79, withdrawals of ground water decreased in the Pasadena, Katy, Baytown-La Porte, Johnson Space Center, Texas City, and Alta Loma areas but increased in the Houston area. The decreased withdrawals in the Katy area resulted partly from a small decrease in the acreage of rice planted, but mostly from a decrease in water needed for irrigation during 1979. The pumping of ground water increased in the Houston area because of the growth in population. From spring 1975 to spring 1980, water levels rose in the southeastern one-half of the district and declined in the northwestern one-half. The maximum rise of water levels in wells in the Chicot aquifer was 110 feet (33.5 meters); the maximum rise in wells in the Evangeline aquifer was 150 feet (45.7 meters). The maximum decline of water levels in wells in the Chicot aquifer was 60 feet (18.3 meters); the maximum decline in wells in the Evangeline aquifer was 70 feet (21.3 meters). No significant changes occurred in the chloride concentration in water from wells in the Alta Loma area during 1975-79. The concentration of chloride in water from a well completed in the middle part of the Chicot aquifer at Hitchcock is increasing, probably because of updip migration of the freshwater-saltwater interface.

Open-File Report↗

Ground-water records for eastern Oklahoma, Part 2; water-quality records for wells, test-holes, and springs

The U. S. Geological Survey has collected data on Oklahoma's ground-water resources since 1934. Most of these data were collected as part of specific ground-water studies conducted in cooperation with various Federal, State, and local agencies. Data on construction, yield, water levels, and other physical well parameters are given in 'Ground-Water Records for Northeastern Oklahoma, Part 1 - Records of Wells, Test Holes, and Springs' and in 'Ground-Water Records for Southeastern Oklahoma, Part 1 - Records of Wells, Test Holes, and Springs.' These reports are available from the U.S. Department of the Interior, Geological Survey, Rm. 621, 201 N.W. Third, Oklahoma City, OK 73102. Although some water-quality data for wells, test-holes, and springs have been published, they are scattered through a variety of reports and are not readily available on a regional basis. Furthermore, a considerable amount of data have never been published and can be obtained only from the files of the Geological Survey. The purpose of this report is to make available both published and unpublished water-quality records for approximately 1,740 wells, test-holes, and springs in 23 counties in northeastern Oklahoma and 16 counties in southeastern Oklahoma. Acknowledgment is extended to the many hundreds of individuals who have provided the data compiled in this report.

Oklahoma↗

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

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

Open-File Report↗

Ground-water hydrology of the Hollister and San Juan Valleys, San Benito County, California, 1913-68

The Hollister and San Juan Valleys are within the Gilroy-Hollister ground-water basin. That part of the ground-water basin underlying the valleys consists of three subbasins each of which contains two or more ground-water subunits. The subbasin and subunit boundaries are formed by known or postulated faults, folded sedimentary rocks, and igneous rocks. The principal water-bearing units are lenticular beds of sand and gavel interbedded with clay, silt, sand, and gravel, or their locally consolidated equivalents, which range from Pliocene to Holocene, in age. Ground water occurs mainly under artesian or semiartesian conditions but also under unconfined (water-table) conditions in areas adjacent to most surface streams and, locally, under perched or semiperched conditions. In 1968 the depth to water in wells ranged from approximately 20 feet above land surface to more than 200 feet below land surface. Water-level differences in wells across the boundaries of adjacent subunits ranged from about 1 to more than 100 feet.

Open-File Report↗

Capillary losses from ground water

A method is presented for estimating the discharge of ground water by evapotranspiration of water rising from the water table by capillarity. ‘Potential capillary water loss’ is defined as a measure of the ability of the capillary interstices of a soil to raise water from the water table to the ground surface. Published equations describing soil‐moisture movement and published graphs relating capillary conductivity and capillary potential are used to derive expressions of the relation between ‘potential capillary water loss’ and depth to the water table in a given soil. On the basis of these theoretical relationships, graphs are drawn that show how the depth to the water table affects the ability of a particular soil to raise water to the ground surface under given conditions. The application of these methods is discussed in relation to the estimation of ground‐water losses by capillary rise, the determination of potential evapotranspiration, and the analysis of soil‐tank data. Their essential agreement with empirical profiles of capillary potential obtained in soil tanks demonstrates their usefulness.

Eos, Transactions, American Geophysical Union↗

Ground-water provinces of Brazil

As part of a study of the status of investigations and development of ground water in Brazil, made under the auspices of the United States International Cooperation Administration and with the cooperation of the Government of Brazil, the country was divided into seven ground-water provinces. The identification and delineation of the provinces were based on the regional distribution of the dominant geologic units which are known or inferred to have distinctive water-bearing characteristics. Three of the provinces, covering most of the country, are underlain by Precambrian crystalline rocks. Three others coincide in part with four extensive sedimentary basins--the Parnaiba or Maranhfio basin and the contiguous Sao Francisco basin in the northeast and east, the Amazon basin in the north and northwest, and the Paranfi basin in the south and southwest. In addition, the narrow, discontinuous coastal plain is considered as a province. the occurrence of ground water is discussed briefly, and pertinent data are given on the more important aquifers, together with information on some existing wells. Because of the widespread distribution of crystalline rocks of low permeability, it is difficult in many areas to develop large or even adequate ground-water supplies. In general, satisfactory supplies of water are available in most of the rest of the country. Some problems include the relative deficiency of rainfall in the northeast together with the occurrence, in parts of this region, of mineralized water in the crystalline rocks. Also, there is a potential problem of excessive lowering of water levels and interference among wells in the intensively developed area of the city of Sao Paulo.

Water Supply Paper↗

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

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

Open-File Report↗

Hydrogeologic Framework and Ground Water in Basin-Fill Deposits of the Diamond Valley Flow System, Central Nevada

The Diamond Valley flow system, an area of about 3,120 square miles in central Nevada, consists of five hydrographic areas: Monitor, Antelope, Kobeh, and Diamond Valleys and Stevens Basin. Although these five areas are in a remote part of Nevada, local government officials and citizens are concerned that the water resources of the flow system eventually could be further developed for irrigation or mining purposes or potentially for municipal use outside the study area. In order to better understand the flow system, the U.S. Geological Survey in cooperation with Eureka, Lander, and Nye Counties and the Nevada Division of Water Resources, is conducting a multi-phase study of the flow system. The principal aquifers of the Diamond Valley flow system are in basin-fill deposits that occupy structural basins comprised of carbonate rocks, siliciclastic sedimentary rocks, igneous intrusive rocks, and volcanic rocks. Carbonate rocks also function as aquifers, but their extent and interconnections with basin-fill aquifers are poorly understood. Ground-water flow in southern Monitor Valley is from the valley margins toward the valley axis and then northward to a large area of discharge by evapotranspiration (ET) that is formed south of a group of unnamed hills near the center of the valley. Ground-water flow from northern Monitor Valley, Antelope Valley, and northern and western parts of Kobeh Valley converges to an area of ground-water discharge by ET in central and eastern Kobeh Valley. Prior to irrigation development in the 1960s, ground-water flow in Diamond Valley was from valley margins toward the valley axis and then northward to a large discharge area at the north end of the valley. Stevens Basin is a small upland basin with internal drainage and is not connected with other parts of the flow system. After 40 years of irrigation pumping, a large area of ground-water decline has developed in southern Diamond Valley around the irrigated area. In this part of Diamond Valley, flow is from valley margins toward the irrigated area. In northern Diamond Valley, flow appears to remain generally northward to the large discharge area. Subsurface flow through mountain ranges has been identified from Garden Valley (outside the study area) through the Sulphur Springs Range to Diamond Valley and from southeastern Antelope Valley through the Fish Creek Range to Little Smoky Valley (outside the study area). In both cases, the flow is probably through carbonate rocks. Ground-water levels in the Diamond Valley flow system have changed during the past 40 years. These changes are the result of pumpage for irrigation, municipal, domestic, and mining uses, mostly in southern Diamond Valley, and annual and longer-term variations in precipitation in undeveloped parts of the study area. A large area of ground-water decline that underlies an area about 10 miles wide and 20 miles long has developed in the basin-fill aquifer of southern Diamond Valley. Water levels beneath the main part of the irrigated area have declined as much as 90 feet. In undeveloped parts of the study area, annual water-level fluctuations generally have been no more than a few feet.

Scientific Investigations Report↗

Ground-water quality of the Upper Floridan Aquifer near an abandoned manufactured gas plant in Albany, Georgia

Manufactured gas plants produced gas for heating and lighting in the United States from as early as 1816 into the 1960's. By-products including, but not limited to, oil residues and tar, were generated during the gas-manufacturing process. Organic compounds (hydrocarbons) were detected in water in the upper water-bearing zone of the Upper Floridan aquifer near an abandoned manufactured gas plant (MGP) in Albany, Georgia, during an earlier investigation in 1990. Chemical analyses of ground-water samples collected from five existing monitoring wells in 1991 verify the presence of hydrocarbons and metals in the upper water-beating zone of the Upper Floridan aquifer. One well was drilled into the lower water-beating zone of the Upper Floridan aquifer in 1991 for water-quality sampling and water-level monitoring. Analyses of ground water sampled from this well did not show evidence of benzene, toluene, xylene, napthalene, acenaphthlene, or other related compounds detected in the upper water-bearing zone in the study area. Low concentrations of tetrachloroethane, trichloromethane, and l,2-cisdichloroethene were detected in a water sample from the deeper well; however, these compounds were not detected in the upper water-bearing zone in the study area. Inorganic constituent concentrations also were substantially lower in the deeper well. Overall, ground water sampled from the lower water-bearing zone had lower specific conductance and alkalinity; and lower concentrations of dissolved solids, iron, and manganese compared to ground water sampled from the upper water-bearing zone. Water levels for the upper and lower water-bearing zones were similar throughout the study period.

Georgia↗

Maps showing ground-water conditions in the northern part of the Gila River drainage from Painted Rock Dam to Texas Hill area, Maricopa, Pima, and Yuma Counties, Arizona; 1978

The Gila River drainage from Painted Rock Dam to Texas Hill area includes about 3,000 square miles in southwestern Arizona. Ground-water development has taken place only in the northern part of the area, and only this part is included in the report. The southwestward-flowing Gila River drains the 1 ,900-square-mile northern part of the area. The main water-bearing unit is the valley-fill deposits. Since 1967, the estimated ground-water pumpage has exceeded 100,000 acre-feet per year, and in 1977 the ground-water pumpage was 210,000 acre-feet; the ground water is used mainly for irrigation. The ground-water withdrawals have resulted in general water-level declines in most of the area. Information shown on the maps includes change in water level, 1965-78 and 1973-78, and irrigated area; depth to water, altitude of the water level, and well depth; and specific conductance and fluoride concentration in the water. Hydrographs of the water level in selected wells and a table of historical pumpage also are included. Scale 1:250 ,000.

Arizona↗

Effects of Pumping on Ground-Water Flow Near Water-Supply Wells in the Lower Potomac-Raritan-Magothy Aquifer, Pennsauken Township, Camden County, New Jersey

Since the 1970's, hexavalent chromium has been detected in concentrations as great as 1.0 milligram per liter in wells at the Puchack well field operated by the Camden City Department of Utilities, Water Division (Water Department), forcing the Water Department to progressively remove five of its six wells from service between 1975 and 1988. The wells in the Puchack well field range in depth from 140 to 220 feet and are screened in the Lower Potomac-Raritan-Magothy aquifer. The Water Department has continued to pump Puchack Well 1 to maintain a hydraulic gradient toward the well field in an attempt to limit contaminant migration. In late 1997, concerns about treating the water withdrawn from Puchack Well 1 led water managers to consider temporarily discontinuing the pumping. In the spring of 1998, the U.S. Geological Survey (USGS), in cooperation with the New Jersey Department of Environmental Protection, began a preliminary assessment of the potential effects of temporarily removing Puchack Well 1 from service. Water levels in the Lower Potomac-Raritan-Magothy aquifer were measured during both pumping and nonpumping conditions to determine the direction and velocity of ground-water flow and the results were compared. Data collected in late March and early April 1998 indicate the presence of a ground-water divide between the Puchack well field and the Morris and Delair well fields when Puchack Well 1 was being pumped. A similar divide also was present when the well was not being pumped. The position and persistence of this divide limits the probability that contaminants in the vicinity of the Puchack well field will reach the Delair and Morris well fields during either pumping condition. Another divide southeast of Puchack Well 1 while the well was being pumped was no longer evident when the pumping was stopped and water levels had recovered. Under non-pumping conditions, ground water between Puchack Well 1 and this divide could begin to migrate toward other large pumping centers to the southeast. The average linear ground-water velocity along an arbitrarily selected southeast-trending flow path was estimated to be from 221 to 332 feet per year. This estimate indicates that any contaminated ground water that may be present within the area influenced by pumping at Puchack Well 1 may begin to move toward the pumping centers less than 2 miles to the southeast if Puchack Well 1 is either temporarily or permanently removed from service.

Water-Resources Investigations Report↗

Hydrologic data for 1994-96 for the Huron Project of the High Plains Ground-Water Demonstration Program

This report presents data on precipitation, water levels, and water quality that have been collected or compiled for water years 1994 through 1996 for the Huron Project of the High Plains Ground-Water Demonstration Program, under the guidance of the Bureau of Reclamation. This is the second report for the project. The first report (Carter, 1995) presented data collected through water year 1993. The purpose of the Huron Project is to demonstrate the artificial recharge potential of glacial aquifers in eastern South Dakota. High flows from the James River during spring runoff were used as a source of supplemental recharge for the Warren aquifer, which is a buried, glacial aquifer. In 1990, 70 observation wells were installed by the South Dakota Department of Environment and Natural Resources (DENR) specifically for this study, and 15 existing DENR observation wells were incorporated into the study. In 1993, the recharge well was installed. After a trial injection of recharge water in April 1994, continuous injection began in June 1994. Many sites were monitored to obtain information before, during, and after recharging the aquifer. This report presents data that were collected during the three phases of recharge. Precipitation data are collected at two sites within the study area. A site description and daily precipitation for water years 1994-95 are presented for one precipitation site. Water-level hydrographs are presented for the 85 observation wells and the recharge well. Hydrographs are shown for the period from October 1, 1993, through November 29, 1995. Recharge water was injected from June 2, 1994, through July 29, 1994, and from June 14, 1995, through September 13, 1995. The cumulative volume of injected water and the injection rates into the aquifer are presented for the periods of recharge. Water-quality data were collected from screening, detailed, and plume-monitoring sampling programs. Screening water-quality data for six observation wells are presented. These data include primarily field parameters and common ions. The four detailed sampling sites represent the quality of untreated water, treated water, and ground water from the Warren aquifer. Data presented for the detailed sampling program include field parameters, bacteria counts, and concentrations of common ions, solids, nutrients, trace elements, radiometrics, total organic carbon, herbicides, insecticides, and volatile organic compounds. Water-quality data for the plume-monitoring sampling program were collected from 25 sites during injection of recharge water into the Warren aquifer in 1994 and 1995. The data for the plume-monitoring program include primarily field parameters and common ions. Data for quality-assurance samples also are presented.

Open-File Report↗

Characterization of ground-water discharge from bedrock aquifers to the Mississippi and Minnesota Rivers at three areas, Minneapolis-St. Paul area, Minnesota

The hydrogeology at three areas along the Mississippi and Minnesota Rivers in the Minneapolis-St. Paul area were studied to characterize ground-water discharge from bedrock aquifers to the two rivers. Along the Mississippi River between Fridley and Brooklyn Center, a buried valley underlying the Mississippi River cuts through the overlying terrace deposits and glacial-drift deposits into two underlying bedrock hydro- geologic units: the St Peter aquifer, and a rubble zone between the St. Peter and Prairie du Chien-Jordan aquifers. Shallow ground-water flow in the near-surface gray and upper red tills and sand and gravel outwash aquifer discharges to springs along the edge of the river. Ground water flowing through the rubble zone and upper part of the Prairie du Chien-Jordan aquifer probably discharges through alluvial deposits to the river. In study area 2, along the Minnesota River between Eagan and Bloomington, almost 200 feet of post-glacial alluvium, glaciofluvial sand and gravel, Pleistocene lake deposits, and peat fill a bedrock valley under the present-day Minnesota River. As much as 40 feet of post-glacial peat, silty clay, clay, and muck lie near the river-valley walls. Confining units beneath the river channel impede the discharge of ground water from the underlying Prairie du Chien-Jordan aquifer to the river. Ground water discharges to wetlands, lakes, and springs along both the north and south side of the river. Along the Mississippi River at Minneapolis about 5 miles upstream of the confluence of the Minnesota and Mississippi Rivers, the Mississippi River lies in a post-glacial valley cut through thin glacial drift into the St. Peter aquifer. Beneath the river, ground water flows from the St. Peter aquifer through the overlying post-glacial ailuvium to the Mississippi River. No confining unit separates the St. Peter aquifer and the river.

Minnesota↗

Sources and migration pathways of natural gas in near-surface ground water beneath the Animas River valley, Colorado and New Mexico

In July 1990, the U.S. Geological Survey began a study of the occurrence of natural gas in near-surface ground water in the Animas River valley in the San Juan Basin between Durango, Colorado, and Aztec, New Mexico. The general purpose of the study was to identify the sources and migration pathways of natural gas in nearsurface ground water in the study area. The purpose of this report is to present interpretive conclusions for the study, primarily based on data collected by the U.S. Geological Survey from August 1990 to May 1991. Seventy of the 205 (34 percent) groundwater samples collected during August-November 1990 had methane concentrations that exceeded the reporting limit of 0.005 milligram per liter. The maximum concentration was 39 milligrams per liter, and the mean concentration was 1.3 milligrams per liter. Samples from wells completed in bedrock have greater mean concentrations of methane than samples from wells completed in alluvium. Correlations indicate weak or nonexistent associations between dissolved-methane concentrations and concentrations of dissolved solids, major ions, bromide, silica, iron, manganese, and carbon dioxide. Dissolved methane was associated with hydrogen sulfide. Soil-gas-methane concentrations were measurable at few of 192 ground-water sites, even at sites at which ground water contained large concentrations of dissolved methane, which indicates that soil-gas surveys are not useful to delineate areas of gas-affected ground water. The reporting limit of 0.005 milligram per liter of gas was equaled or exceeded by 40 percent of soil-gas measurements adjacent to 352 gas-well casings. Concentrations of at least 100 milligrams per liter of gas were measured at 25 (7 percent) of the sites. Potential sources of gases in water, soil, gas-well surface casings, and cathodic-protection wells were determined on the basis of their isotopic and molecular compositions and available information about gas-well construction or leaks. Biogenic and thermogenic sources of gas exist in the near-surface environment of the study area. Biogenic gas is present locally in the near-surface Animas and Nacimiento formations, and biogenic gas has been detected in water wells completed in those rocks. Most gas probably is thermogenic gas from deep reservoirs, including the Dakota Sandstone, Mesaverde Group, Lewis Shale, Pictured Cliffs Sandstone, and coals in the Fruitland Formation. Less important sources include sandstones in the upper Fruitland Formation and the Kirtland Shale. Although migration of gas by diffusion or through natural fractures is possible, manmade conduits probably account for most of the upward migration of gas to the near-surface environment of the study area. Primary migration pathways largely consist of 1) leaking, conventional gas wells and 2) uncemented annuli of conventional gas wells along coals in the Fruitland Formation. Secondary migration pathways are gas-well annuli, cathodic-protection wells, seismic-test holes, and bedrock water wells.

Colorado, New Mexico↗

Ground water in the Crow Creek-Sand Lake area, Brown and Marshall Counties, South Dakota

The Crow Creek Sand Lake area is in the northeastern part of South Dakota and consists of flat to gently rolling land. It is roughly 25 miles square and is bounded on the west by the James River, on the north by the North Dakota State line, and on the south and east by arbitrary land lines. Natural drainage, which is very poor, is augmented by a now very dilapidated system of man made drains; undrained or poorly drained potholes and sloughs are common. Most of the report area is in the drainage basin of Crow Creek, a tributary of the James River. About 60 square miles along the west border of the area is drained directly by the James River; and about 36 square miles in the northeastern corner of the area is drained by the Wild Rice River, a tributary of the Red River of the North. Granite and other related rocks of Precambrian age underlie the entire area below a depth of about 1,100 to 1,200 feet. Under part of the area these rocks are overlain by the Sioux quartzite, also of Precambrian age. Next above is the Dakota sandstone of Cretaceous age, which is about 250 feet thick and is the aquifer tapped by more than 600 deep wells in the area. The Dakota sandstone in turn is overlain by younger formations of Cretaceous age, which include the Graneros shale, Greenhorn limestone, Carlile shale, Niobrara formation, and Pierre shale. These younger formations have an aggregate thickness of about 700 to 950 feet and generally do not yield water. Mantling, the consolidated stratified rocks are unconsolidated deposits of Quaternary age that are absent locally but in places are as much as 200 feet thick. These deposits consist principally of glacial outwash, glacial till, and lake sediments and are the source of water for all shallow wells in the area. Precipitation is the principal source of recharge to the ground-water reservoir tapped by the shallow wells. The water table ranges in depth from less than 1 foot to a little more than 30 feet below the land surface; in July 1951 the depth to water was less than 5 feet in 15 percent of the area and 5 to 10 feet in an additional 25 percent of the area. Because the hydraulic gradient in most of the area is less than 10 feet per mile and because much of the water-bearing material is only slightly permeable, lateral movement of the ground water in the unconsolidated deposits is exceedingly slow. Transpiration by vegetation and evaporation account for most of the ground water discharged in the area; relatively little ground water is discharged by streams, wells, and springs, or as underflow out of the area. Much of the low-lying land is waterlogged. However, by improving and cleaning both the natural and artifical drains and by lowering the water table by pumping, waterlogging can be materially decreased and its recurrence prevented.

North Dakota↗

Ground-water hydrology of the San Pitch River drainage basin, Sanpete County, Utah

The San Pitch River drainage basin in central Utah comprises an area of about 850 square miles; however, the investigation was concerned primarily with the Sanpete and Arapien Valleys, which comprise about 250 square miles and contain the principal ground-water reservoirs in the basin. Sanpete Valley is about 40 miles long and has a maximum width of 13 miles, and Arapien Valley is about 8 miles long and 1 mile wide. The valleys are bordered by mountains and plateaus that range in altitude from 5,200 to 11,000 feet above mean sea level. The average annual precipitation on the valleys is about 12 inches, but precipitation on the surrounding mountains reaches a maximum of about 40 inches per year. Most of the precipitation on the mountains falls as snow, and runoff from snowmelt during the spring and summer is conveyed to the valleys by numerous tributaries of the San Pitch River. Seepage from the tributary channels and underflow beneath the channels are the major sources of recharge to the ground-water reservoir in the valleys. Unconsolidated valley fill constitutes the main ground-water reservoir in Sanpete and Arapien Valleys. The fill, which consists mostly of coalescing alluvial fans and flood deposits of the San Pitch River, ranges in particle size from clay to boulders. Where they are well sorted, these deposits yield large quantities of water to wells. Numerous springs discharge from consolidated rocks in the mountains adjacent to the valleys and along the west margin of Sanpete Valley, which is marked by the Sevier fault. The Green River Formation of Tertiary age and several other consolidated formations yield small to large quantities of water to wells in many parts of Sanpete Valley. Most water in the bedrock underlying the valley is under artesian pressure, and some of this water discharges upward into the overlying valley fill. The water in the valley fill in Sanpete Valley moves toward the center of the valley and thence downstream. The depth to water along parts of the sides of the valley is more than 100 feet, but in much of the central part of the valley, the water level is at or above the land surface. The valley fill pinches out in the southern part of the valley, and most of the ground water moves to the surface, where it discharges into the San Pitch River or is consumed by evapotranspiration. Ground water is discharged principally by wells, springs, and evapotranspiration. The discharge from wells varies considerably from year to year because most of the water is used for irrigation, and the wells are used only as necessary to supplement the available surface-water supply. Thus, in 1965, a year of above-normal precipitation, the discharge from wells was 12,000 acre-feet, whereas in 1966, a year of below-normal precipitation, the wells discharged 21,000 acre-feet. The discharge from springs during 1966 was estimated to be 36,000 acre-feet, and an additional 113,000 acre-feet of water was discharged by phreatophytes. Water levels in the valleys, for the most part, fluctuate in direct response to variations in precipitation, and the discharge from wells has had little long-term effect on water levels. Approximately 3 million acre-feet of water available to wells is stored in the upper 200 feet of saturated valley fill. The ground water in most parts of the valleys is fresh and suitable for public supply and irrigation. The Green River and Crazy Hollow Formations may, in some places, yield slightly or moderately saline water.

Utah↗

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