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At least 1,531 records · Page 85Linked to original sources
USGS1987

Generalized potentiometric surface of the Sparta-Memphis aquifer, eastern Arkansas, spring 1980

A map shows generalized contours of the altitude of water levels for wells completed in the Sparta-Memphis aquifer in eastern Arkansas. Most water-level measurements used in constructing the map were from the spring of 1980, but supplemental measurements from other years indicated no long-term change in water levels. Hydrographs for selected wells are included to show trends and lack of trends in water-level changes. The aquifer in the Sparta Sand and Memphis Sand of Eocene age which consists of fine to medium sand interbedded with salt, clay, and lignite. The aquifer supplies much of the water used for industry and public supply for eastern Arkansas. Some irrigation users also obtain supplies from the aquifer. Cones of depression caused by pumpage for industrial and public supplies occur near Camden, El Dorado, Magnolia, Pine Buff, and West Memphis.

Arkansas↗
USGS1963

Public water supplies in Gloucester County, New Jersey

Gloucester County is in the southwestern part of New Jersey, below Camden, and is a part of the Lower Delaware River Valley. This area is attracting new industry and has shown a population increase of about 47 percent from 1950 to 1960, mostly urban. With the economic growth of the county, the availability and quality of water become increasingly important. The county is in the Coastal Plain of New Jersey. It is underlain by unconsolidated sands and clays of Quaternary, Tertiary, and Cretaceous age. The Raritan and Magothy Formations constitute the most important aquifers and yield more than 95 percent of the water pumped by the public water systems in the county. These formations are capable of yielding 1,400 gpm (gallons per minute) or more to large diameter wells. High yielding wells generally can be drilled anywhere in the county, although the formations are deeper toward the Atlantic Ocean. The Cohansey Sand, second most important aquifer, yields up to 800 gpm or more from large diameter wells. This aquifer is present only in the sparsely populated southeastern half of the county. The Wenonah Formation and Mount Laurel Sand are capable of yielding 100 to 200 gpm in certain areas. The overall chemical quality of the naturally occurring ground water is good. The water generally meets the U.S. Public Health Service's (1962) suggested limit for dissolved solids; however, in some areas, the water carries objectionable amounts of iron and nitrate in solution and has a low pH. Contamination of ground water by salt-water encroachment or by pollution from industrial activity or organic waste in densely populated areas should be prevented. The quality rather than the quantity of water may be the important factor in future ground-water developments. The 21 public water systems in Gloucester County pumped about 1.3 billion gallons of water during 1948 and some 2.7 billion gallons during 1959. This is slightly more than a hundred percent increase in pumpage in 12 year s. The average per capita public water supply consumption in 1959 was approximately 75 gallons per day. This report includes a summary of the history of the present installations, groundwater conditions, quality and availability of water, and potential future yield for the 2 public water systems in Gloucester County.

New Jersey↗
USGS1987

Instream water use in the United States: water laws and methods for determining flow requirements

Water use generally is divided into two primary classes - offstream use and instream use. In offstream use, sometimes called out-of-stream or diversionary use, water is withdrawn (diverted) from a stream or aquifer and transported to the place of use. Examples are irrigated agriculture, municipal water supply, and industrial use. Each of these offstream uses, which decreases the volume of water available downstream from the point of diversion, is discussed in previous articles in this volume. Instream use, which generally does not diminish the flow downstream from its point of use, and its importance are described in this article. One of the earliest instream uses of water in the United States was to turn the water wheels that powered much of the Nation's industry in the 18th and 19th centuries. Although a small volume of water might have been diverted to a mill near streamside, that water usually was returned to the stream near the point of diversion and, thus, the flow was not diminished downstream from the mill. Over time, the generation of hydroelectric power replaced mill wheels as a means of converting water flow into energy. Since the 1920's, the generation of hydroelectric power increasingly has become a major instream use of water. By 1985, more than 3 billion acre-feet of water (3,050,000 million gallons per day) was used annually for hydropower generation (Solley and others, 1988, p. 45)-enough water to cover the State of Colorado to a depth of 51 feet. Navigation is another instream use with a long history. The Lewis and Clark expedition journals and many of Mark Twain's novels illustrate the extent to which the Nation originally depended on adequate streamfiows for basic transportation. Navigation in the 1980's is still considered to be an instream use; however, it often is based upon a stream system that has been modified greatly through channelization, diking, and construction of dams and locks. The present (1987) inland water navigation system in the conterminous United States consists of about 12,000 miles of maintained waterways, over which about 500 million tons of cargo is carried each year (U.S. Army Corps of Engineers, 1988, p. 16). Although not so widely practiced in recent years, streams have been used to dispose of raw waste products from homes, communities, and factories. This use has been discouraged by law and public policy because of public health concerns and the damage it causes to the environment. Beginning in the mid-1960's, other instream uses gained new prominence in the water-resources arena-the assertion of a legal right to a free-flowing stream for biological, recreational, and esthetic purposes. These uses themselves, however, are not new. Riverine habitat always has produced fish, and the beauty of flowing water always has evoked a strong sense of esthetic appreciation. What is new is the emerging legitimacy and awareness of these noneconomic uses under State and Federal laws and regulations. In the past, environmental uses of flowing water were ignored, for the most part, under a long-standing legal tradition that favored offstream uses and certain instream uses that had a strong economic basis. The history of instream-flow policy debate really concerns those recently recognized types of interim uses. Although the more transitional water uses have been protected by law, the recognition of other in stream uses has resulted in substantial changes in State water laws. Although methods for determining the volume of water needed for most traditional water uses are relatively straight-forward and well-established, methods for determining water requirements for the in stream uses have been developed only recently and are continuing to evolve. Water laws that have favored the more traditional water uses, the inherent nature of conflict between instream and offstream water uses, and the special kinds of technological and philosophical problems posed by the "newer" types of instream uses are described below. Water laws that have been passed to accommodate the more recently recognized instream uses are summarized.

Report↗
USGS1986

Water resources of Clallam County, Washington: Phase I report

An inventory of the water resources of Clallam County, Washington, showed that sufficient water is available to supply all present demands. Domestic water supplies can be obtained from wells drilled 100 ft or less into glacial and alluvial deposits; in areas underlain by bedrock, wells more than 100 ft deep can generally supply one home per well. Surface water is abundant, and is the source for most public water systems. Extreme low flows were observed only in small drainage basins in bedrock in the mountainous interior and along parts of the coastline in the Strait of Juan de Fuca. The quality of ground and surface waters is generally excellent. In coastal areas, some wells may yield water with large concentrations of chloride and dissolved solids. A quarter of the wells tested had excessive concentrations of iron and (or) manganese. High values of turbidity, color, and coliform bacteria are widespread surface water problems, but standard filtering and chlorination treatment make the water suitable for public supplies. High concentrations of coliform bacteria apparently originate naturally in soils. High ammonia concentration observed at one site is probably caused by sewage disposal practices. (USGS)

Washington↗
USGS2023

Exposures and potential health implications of contaminant mixtures in linked source water, finished drinking water, and tapwater from public-supply drinking water systems in Minneapolis/St. Paul area, USA

Continued improvements in drinking-water quality characterization and treatment/distribution infrastructure are required to address the expanding number of documented environmental contaminants. To better understand the variability in contaminant exposures from the drinking water resource (surface and groundwater), through the distribution process, to the point-of-use (tapwater), in 2019 a synoptic assessment of broad chemical exposures was conducted in system-specific source waters, finished drinking water and service-area tapwater from 10 drinking water treatment facilities in the greater Minneapolis/St. Paul area of Minnesota, United States. Source water, finished water (collected pre-distribution in the treatment facility), and tapwater samples were analyzed for 465 unique organic compounds, 34 inorganic constituents, and 3 field parameters as well as in vitro estrogen, androgen, and glucocorticoid bioactivities. Mixtures of organic and inorganic contaminants were prevalent in source water, finished water, and tapwater samples, indicating the continued need for broad assessments of mixed contaminant exposures to characterize potential drinking-water human health outcomes. Contaminant concentrations were similar among drinking water sources and no exceedances of Environmental Protection Agency maximum contaminant level(s) (MCL) were observed in any treated sample (finished water or tapwater) in this study. No treated sample contained estrogenic, androgenic, or glucocorticoid activity at concentrations that may cause adverse human health effects. However, there were multiple exceedances of non-enforceable MCL goal(s) (MCLG), and other health advisories combined with frequent exceedances of benchmark-based hazard indices in both finished water and tapwater samples. These results indicate that exposure to contaminant mixtures is a potential public health concern underscoring our continued efforts to assess contaminant mixture exposures at the drinking-water point of consumption using a broad analytical scope.

Minnesota↗
USGS1989

Methods for collection and analysis of aquatic biological and microbiological samples

The series of chapters on techniques describes methods used by the U.S. Geological Survey for planning and conducting water-resources investigations. The material is arranged under major subject headings called books and is further subdivided into sections and chapters. Book 5 is on laboratory analysis. Section A is on water. The unit of publication, the chapter, is limited to a narrow field of subject matter. "Methods for Collection and Analysis of Aquatic Biological and Microbiological Samples" is the fourth chapter to be published under Section A of Book 5. The chapter number includes the letter of the section. This chapter was prepared by several aquatic biologists and microbiologists of the U.S. Geological Survey to provide accurate and precise methods for the collection and analysis of aquatic biological and microbiological samples. Use of brand, firm, and trade names in this chapter is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. This chapter supersedes "Methods for Collection and Analysis of Aquatic Biological and Microbiological Samples" edited by P.E. Greeson, T.A. Ehlke, G.A. Irwin, B.W. Lium, and K.V. Slack (U.S. Geological Survey Techniques of Water-Resources Investigations, Book 5, Chapter A4, 1977) and also supersedes "A Supplement to-Methods for Collection and Analysis of Aquatic Biological and Microbiological Samples" by P.E. Greeson (U.S. Geological Survey Techniques of Water-Resources Investigations, Book 5, Chapter A4), Open-File Report 79-1279, 1979.

Techniques of Water-Resources Investigations↗
USGS2017

Fisheries and aquatic resources of Prairie Creek, Redwood National Park

This report synthesizes information on the status of fisheries and aquatic resources in the Prairie Creek sub-basin of Redwood Creek in Humboldt County in northern California, founded on a bibliographic search we conducted of historic and current datasets, unpublished reports, theses, and publications. The compiled Prairie Creek Fisheries Bibliography is available at https://irma.nps.gov/DataStore/. This report describes life histories and population status of the salmonid fishes, and species occurrence of non-salmonid fishes, amphibians, macroinvertebrates, and common benthic algae in Prairie Creek. We assessed habitat conditions that may limit salmonid production in relation to recovery targets established by the National Marine Fisheries Service and the State of California. Although salmon abundance has decreased from historic levels, production of juvenile salmonids in Prairie Creek is relatively stable and robust in comparison with the rest of the Redwood Creek Basin. Carrying capacity likely differs between the undisturbed upper reaches of Prairie Creek and reaches in the lower creek, the latter of which are affected by legacy impacts from timber and agricultural activities. Increased sediment supply and lack of channel structure and floodplain connection in lower Prairie Creek appear to be the greatest stressors to salmonid production. Existing datasets on aquatic resources and environmental variables are listed, and subject areas where few data are available are identified .

California↗
USGS1987

Arctic National Wildlife Refuge, Alaska, Coastal Plain Resource Assessment: Report and recommendation to the Congress of the United States and final legislative environmental impact statement

The Arctic National Wildlife Refuge, in the northeastern corner of Alaska, was first established as the Arctic National Wildlife Range by Public Land Order 2214 in 1960, for the purpose of preserving unique wildlife, wilderness, and recreational values. The original 8.9-millionacre Range was withdrawn from all forms of appropriation under the public land laws, including mining laws but not including mineral leasing laws. This order culminated extensive efforts begun more than a decade earlier to preserve this unique part of Alaska. The following report analyzes the potential environmental consequences of five management alternatives for the coastal plain, ranging from opening for lease of the entire area for oil and gas development, to wilderness designation. A legislative environmental impact statement has been integrated into the report.

Alaska↗
USGS2020

Water resources in the Cheyenne and Arapaho Tribal jurisdictional area, west-central Oklahoma, with an analysis of data gaps through 2015

This report provides an overview of existing hydrologic information describing the quality, quantity, and extent of the major surface-water and groundwater resources in the Cheyenne and Arapaho Tribal jurisdictional area, west-central Oklahoma. Hydrologic information is provided for five major river systems (Cimarron River, North Canadian River, Canadian River, Washita River, and North Fork Red River), two reservoirs (Foss Reservoir and Canton Lake), and eight aquifers consisting of the alluvial aquifers associated with each of the five major river systems and three major bedrock aquifers (Ogallala aquifer, Elk City aquifer, and Rush Springs aquifer). Types of information provided about rivers and reservoirs for the Cheyenne and Arapaho Tribal jurisdictional area include diversion sites and amounts of water allocated and diverted for permitted uses in 2015; treated wastewater discharge sites and amounts discharged in 2015; and characteristics describing water-quality field properties, major ions, nutrients, and selected trace elements. Major ions, nutrients, and selected trace elements are compared to secondary maximum contaminant levels and maximum contaminant levels for finished drinking water. Additionally, statistics are provided describing daily, monthly, and annual streamflow characteristics at 12 U.S. Geological Survey streamgages. Streamflow statistics include the magnitudes and frequencies of floods, base-flow characteristics, and long-term streamflow trends. Types of information provided about the aquifers include amounts of water allocated and pumped for permitted uses in 2015; characteristics of groundwater describing water-quality field properties, major ions, nitrate (measured as nitrogen), and selected trace elements with comparisons to secondary maximum contaminant levels and maximum contaminant levels for finished drinking water; groundwater levels and long-term changes in water levels; and ranges of hydraulic conductivity, aquifer recharge, specific yield, transmissivity, and well yields from reports and groundwater-flow models. Surface water is used primarily for irrigation and mining and other nonconsumptive uses in the Cheyenne and Arapaho Tribal jurisdictional area, except from the Washita and North Fork Red Rivers, where water is treated for use as a public-water supply. Large concentrations of dissolved solids are the primary limiting factor affecting the use of surface water. Median concentrations of dissolved solids in surface water range from less than 1,000 milligrams per liter (mg/L) in samples from the North Canadian River to greater than 9,000 mg/L in samples from the Cimarron River. Large dissolved solids concentrations are correlated with hard water. Median hardness as calcium carbonate concentrations in surface water ranges from 427 mg/L in samples from Canton Lake to 1,000 mg/L in samples from the Washita River. In 2015, groundwater was used at more than twice the rate of surface water in the Cheyenne and Arapaho Tribal jurisdictional area. Although the alluvial aquifers are considered reliably good sources of water in the Cheyenne and Arapaho Tribal jurisdictional area, concentrations of nitrate (measured as nitrogen) exceed the maximum contaminant level of 10 mg/L established by the U.S. Environmental Protection Agency for finished drinking water in parts of all of the alluvial aquifers. Water from the three major bedrock aquifers is used for irrigation, mining, public-water supply, and other uses; however, large concentrations of dissolved solids, nitrate (measured as nitrogen), and naturally occurring trace elements such as arsenic and uranium may limit the use of groundwater as a source of public-water supply in some areas. As of 2015, the depletion of groundwater from the major aquifers in west-central Oklahoma is a minor concern to the Oklahoma Water Resources Board. Groundwater levels and other hydrologic information show that recharge rates exceed the rates of water pumped from aquifers, except in areas that may be affected locally by groundwater depletions.

Oklahoma↗
USGS1998

Chapter A9. Safety in Field Activities

The National Field Manual for the Collection of Water-Quality Data (National Field Manual) describes protocols (requirements and recommendations) and provides guidelines for U.S. Geological Survey (USGS) personnel who collect data used to assess the quality of the Nation's surface-water and ground-water resources. This chapter of the manual addresses topics related to personal safety to be used in the collection of water-quality data, including: policies and general regulations on field safety; transportation of people and equipment; implementation of surface-water and ground-water activities; procedures for handling chemicals; and information on potentially hazardous environmental conditions, animals, and plants. Each chapter of the National Field Manual is published separately and revised periodically. Newly published and revised chapters will be announced on the USGS Home Page on the World Wide Web under 'New Publications of the U.S. Geological Survey.' The URL for this page is http://pubs.usgs.gov/publications/ index.html.

Techniques of Water-Resources Investigations↗
USGS1979

Publications related to the National Water Data Exchange (NAWDEX), 1971-79

The National Water Data Exchange (NAWDEX), formally established in January 1976, is a national confederation of water-oriented organizations working to improve access to water data. Its primary objective is to assist users of water data in the identification, location, and acquistion of useful data. NAWDEX is coordinated by a central Program Office, located within the Water Resources Division of the U.S. Geological Survey, which provides data-exchange policy and guidelines to all participants in the program. In addition to the Program Office, there is a network of Assistance Centers located in 45 States and Puerto Rico which provides direct access to NAWDEX. Membership in NAWDEX is voluntary and open to any water-oriented organization that wishes to participate. This publication contains an alphabetical listing, by author, of the reports that have been produced by the NAWDEX Program Office since 1975, as well as reports from other sources that relate to the development of the NAWDEX program. (Woodard-USGS)

Open-File Report↗
USGS2022

Applied citizen science in freshwater research

Worldwide, scientists are increasingly collaborating with the general public. Citizen science methods are readily applicable to freshwater research, monitoring, and education. In addition to providing cost-effective data on spatial and temporal scales that are otherwise unattainable, citizen science provides unique opportunities for engagement with local communities and stakeholders in resource management and decision-making. However, these methods are not infallible. Citizen science projects require deliberate planning in order to collect high data quality and sustain meaningful community partnerships. Citizen science practitioners also have an ethical responsibility to ensure that projects are not putting the safety of participants at stake. We discuss here how citizen science is being applied in freshwater research, emerging challenges in project planning and implementation, as well as how citizen science is shaping public understanding, policy, and management of freshwaters.

WIREs Water↗
USGS2014

Two approaches for incorporating climate change into natural resource management planning at Wind Cave National Park

Wind Cave National Park (WICA) protects one of the world’s longest caves, has large amounts of high quality, native vegetation, and hosts a genetically important bison herd. The park’s relatively small size and unique purpose within its landscape requires hands-on management of these and other natural resources, all of which are interconnected. Anthropogenic climate change presents an added challenge to WICA natural resource management because it is characterized by large uncertainties, many of which are beyond the control of park and National Park Service (NPS) staff. When uncertainty is high and control of this uncertainty low, scenario planning is an appropriate tool for determining future actions. In 2009, members of the NPS obtained formal training in the use of scenario planning in order to evaluate it as a tool for incorporating climate change into NPS natural resource management planning. WICA served as one of two case studies used in this training exercise. Although participants in the training exercise agreed that the scenario planning process showed promise for its intended purpose, they were concerned that the process lacked the scientific rigor necessary to defend the management implications derived from it in the face of public scrutiny. This report addresses this concern and others by (1) providing a thorough description of the process of the 2009 scenario planning exercise, as well as its results and management implications for WICA; (2) presenting the results of a follow-up, scientific study that quantitatively simulated responses of WICA’s hydrological and ecological systems to specific climate projections; (3) placing these climate projections and the general climate scenarios used in the scenario planning exercise in the broader context of available climate projections; and (4) comparing the natural resource management implications derived from the two approaches. Wind Cave National Park (WICA) protects one of the world’s longest caves, has large amounts of high quality, native vegetation, and hosts a genetically important bison herd. The park’s relatively small size and unique purpose within its landscape requires hands-on management of these and other natural resources, all of which are interconnected. Anthropogenic climate change presents an added challenge to WICA natural resource management because it is characterized by large uncertainties, many of which are beyond the control of park and National Park Service (NPS) staff. When uncertainty is high and control of this uncertainty low, scenario planning is an appropriate tool for determining future actions. In 2009, members of the NPS obtained formal training in the use of scenario planning in order to evaluate it as a tool for incorporating climate change into NPS natural resource management planning. WICA served as one of two case studies used in this training exercise. Although participants in the training exercise agreed that the scenario planning process showed promise for its intended purpose, they were concerned that the process lacked the scientific rigor necessary to defend the management implications derived from it in the face of public scrutiny. This report addresses this concern and others by (1) providing a thorough description of the process of the 2009 scenario planning exercise, as well as its results and management implications for WICA; (2) presenting the results of a follow-up, scientific study that quantitatively simulated responses of WICA’s hydrological and ecological systems to specific climate projections; (3) placing these climate projections and the general climate scenarios used in the scenario planning exercise in the broader context of available climate projections; and (4) comparing the natural resource management implications derived from the two approaches.

Report↗
USGS1993

Development, description, and application of a geographic information system data base for water resources in karst terrane in Greene County, Missouri

A geographic information system data base was developed for Greene County, Missouri, to provide data for use in the protection of water resources. The geographic information system data base contains the following map layers: geology, cave entrances and passages, county and quadrangle boundary, dye traces, faults, geographic names, hypsography, hydrography, lineaments, Ozark aquifer potentio- metric surface, public land survey system, sink- holes, soils, springs, and transportation. Several serious incidents of ground-water contamination have been reported in the karst terrane developed in soluble carbonate rocks in Greene County. Karst terranes are environmentally sensitive because any contaminant carried by surface runoff has the potential for rapid transport through solution enlarged fractures to the ground-water system. In the karst terrane in Greene County, about 2,500 sinkholes have been located; these sinkholes are potential access points for contamination to the ground-water system. Recent examples of ground-water contamination by sewage, fertilizers, and hydrocarbon chemicals have demonstrated the sensitivity of ground water in the Greene County karst terrane to degradation. The ground-water system is a major source of drinking water for Greene County. The population in Greene County, which includes Springfield, the third largest city in Missouri, is rapidly increasing and the protection of the water resources of Greene County is an increasing concern.

Water-Resources Investigations Report↗
USGS2015

Geospatial data for coal beds in the Powder River Basin, Wyoming and Montana

The purpose of this report is to provide geospatial data for various layers and themes in a Geographic Information System (GIS) format for the Powder River Basin, Wyoming and Montana. In 2015, as part of the U.S. Coal Resources and Reserves Assessment Project, the U.S. Geological Survey (USGS) completed an assessment of coal resources and reserves within the Powder River Basin, Wyoming and Montana. This report is supplemental to USGS Professional Paper 1809 and contains GIS data that can be used to view digital layers or themes, including the Tertiary limit of the Powder River Basin boundary, locations of drill holes, clinker, mined coal, land use and technical restrictions, geology, mineral estate ownership, coal thickness, depth to the top of the coal bed (overburden), and coal reliability categories. Larger scale maps may be viewed using the GIS data provided in this report supplemental to the page-size maps provided in USGS Professional Paper 1809. Additionally, these GIS data can be exported to other digital applications as needed by the user. The database used for this report contains a total of 29,928 drill holes, of which 21,393 are in the public domain. The public domain database is linked to the geodatabase in this report so that the user can access the drill-hole data through GIS applications. Results of this report are available at the USGS Energy Resources Program Web site, http://energy.usgs.gov/RegionalStudies/PowderRiverBasin.aspx .

Montana, Wyoming↗
USGS2012

Using persuasive messages to encourage hunters to support regulation of lead shot

Lead shot from hunting adds the toxic metal to environments worldwide. The United States banned lead shot for hunting waterfowl in 1991 and 26 states have lead shot restrictions beyond those mandated for waterfowl hunting. The Minnesota Department of Natural Resources (MDNR) was interested in studying hunter attitudes about expanded restrictions on the use of lead shot for hunting small game to understand what communication strategies might increase public support for potential restrictions on lead shot. We mailed messages about lead shot, including 1,200 control messages and 400 of each of 9 treatment messages, and surveys to 4,800 resident small game hunters. We compared attitudes and intentions related to a possible ban among control and treatment groups. Compared to the control message, all treatment messages elicited more positive attitudes and intentions to support a ban. A basic factual message, messages with references to Ducks Unlimited, and a first-person narrative message generated the strongest support for a ban. Results also demonstrated a substantial relationship between the use of lead shot and response to persuasive messages supporting a ban.

Journal of Wildlife Management↗
USGS2020

Rethinking a groundwater flow system using a multiple-tracer geochemical approach: A case study in Moab-Spanish Valley, Utah

The Glen Canyon Group Aquifer (GCGA) is the sole source of public water supply for the city of Moab, Utah, a domestic and international tourist destination. Population and tourism growth are likely to target the GCGA for future water resources, but our analysis indicates that additional withdrawals would likely be sourced from groundwater storage and not be sustained by recharge. A quantitative estimate of groundwater discharge from the GCGA is problematic because the downgradient aquifer boundary is the Colorado River, and groundwater discharge to the river is very small compared to the river flow. A water budget based on a conceptual model of GCGA discharging into an adjacent alluvial Valley-Fill Aquifer (VFA) was reported by Sumsion (1971) and numerous subsequent studies have repeated and utilized this water budget. The GCGA contains stable isotopes, tritium, 3 He/ 4 He ratios, dissolved solids, and sulfate concentrations that contrast with the VFA, indicating it is instead recharged by local streams rather than from the GCGA. Water-budget calculations, based on: (1) measured spring discharge and streamflow gains, (2) horizontal gradients in VFA groundwater age, and (3) GCGA outcrop area vadose-zone pore waters are all less than previously thought. Using a lumped parameter model and 14 C groundwater ages, we estimate recharge to the deeper GCGA (DGCGA) to be 4.2 ± 2.3 × 10 6 m 3 /yr, which is approximately equal to the measured discharge from wells and springs.

Utah↗