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At least 1,477 records · Page 82Linked to original sources
USGS1980

A catalogue of drill core recovered from Kilauea Iki lava lake, from 1967 to 1979

The purpose of this report is to serve as a descriptive catalogue for drill core recovered from Kilauea Iki lava lake, from 1967 to 1979. Kilauea Iki lava lake was formed when lavas of the 1959 summit eruption were ponded in Kilauea Iki pit crater, a large pit crater at the extreme upper end of Kilauea's east rift zone (Fig. 1). This eruption is one of the best documented of Kilauean eruptions: Murata and Richter (1966) and Richter and Murata (1966) presented data on the chemistry and petrography of the lavas, respectively, and Richter et al. (1970) described the complex filling of the pit crater in considerable detail. Investigation of the lava lake began a few months after the crust stabilized, with the establishment of two perpendicular lines of levelling stations on the surface of the lake. In 1960-62, four holes were drilled through the upper crust in the center of the lake; the crust was 22-44 feet (6.7-13.4 m) thick at that time. Richter and Moore (1966) presented petrographic, modal, and chemical data on the core recovered from this early drilling. The upper crust of Kilauea Iki was drilled again in 1967 by staff members of the Hawaiian Volcano Observatory, and core was recovered from three holes. In 1975, U.S. Geological Survey workers drilled three more holes, each a few feet away from one of the 1 967 holes. A summary of all work done on Kilauea Iki and other Hawaiian lava lakes through 1975 has been given by Wright et al. (1976). The lake has been redrilled twice since 1975, by workers from Sandia Laboratories, as part of their Magma Energy Research program, in cooperation with the U.S. Geological Survey. In 1976, they drilled two holes near the center of the lake. In 1978-79, they drilled a total of six holes; one, commissioned by the U.S. Geological Survey, went completely through the lava lake near its north edge, into the pre-1959 lavas below.

Hawaii↗
USGS1987

Hydrology and chemistry of selected prairie wetlands in the Cottonwood Lake area, Stutsman County, North Dakota, 1979-82

The relation of hydrologic setting and temporal variability in hydrology to nutrient content and geochemical characteristics of a group of prairie wetlands and adjacent ground water was studied during the period 1979-82. Although data were collected from many wetlands and wells at the study site, emphasis in this report primarily is on four wetlands two seasonal and two semipermanent and four wells contiguous to them along a hydrologic section. The seasonal wetlands, T8 and T3, contained water only for a few weeks to months after filling in spring and early summer; both were completely dry by August. The semipermanent wetlands, PI and P8, contained water throughout each year and were ice covered in winter. One wetland, T8, recharges ground water. Wetlands PI and P8 are in areas of ground-water discharge. None of the wetlands received water by channelized surface-water inlets. Only wetland P8 had a channelized surface-water outlet. Ground-water-level data showed that high points of the water table did not always occur beneath land-surface highs. Reversals of ground-water flow occurred occasionally between two of the wetlands, T3 and PI. Significant differences existed in the chemical composition of the wetlands based on their hydrologic setting. In general, the dominant cation and anion in the wetlands were potassium and bicarbonate in wetland T8, calcium and sulfate in wetland T3, magnesium and sulfate in wetland PI, and magnesium and bicarbonate in wetland P8. Significant seasonal differences existed in the water chemistry of the wetlands in ground-water discharge areas. Water in three of the wetlands, T3, Pi, and P8, was most dilute while they filled in spring after icemelt. Concentration increased during the open-water period, and two of the wetlands, PI and P8, became most concentrated under ice cover. Concentrations of total phosphorus and total nitrogen were greatest in wetlands in areas of ground-water recharge and least in wetlands in areas of ground-water discharge. Differences in the chemistry of water from wells in the adjacent ground water resulted primarily from the positions of the wells in the ground-water flow system. The chemical type of water from well 12, which was located in a ground-water recharge area, was calcium sodium bicarbonate. Water from well 4, located downgradient from wetland T8, and from well 16, located downgradient from wetland PI, typically was a calcium sulfate type. Water from well 13, located between wetlands T3 and PI in an area of changing ground-water flow directions, was a magnesium sulfate type. Data from this study show that an understanding of hydrologic conditions is important in the interpretation of the water chemistry of wetlands in the study area.

Professional Paper↗
USGS2013

Overview of groundwater quality in the Piceance Basin, western Colorado, 1946--2009

Groundwater-quality data from public and private sources for the period 1946 to 2009 were compiled and put into a common data repository for the Piceance Basin. The data repository is available on the web at http://rmgsc.cr.usgs.gov/cwqdr/Piceance/index.shtml. A subset of groundwater-quality data from the repository was compiled, reviewed, and checked for quality assurance for this report. The resulting dataset consists of the most recently collected sample from 1,545 wells, 1,007 (65 percent) of which were domestic wells. From those samples, the following constituents were selected for presentation in this report: dissolved oxygen, dissolved solids, pH, major ions (chloride, sulfate, fluoride), trace elements (arsenic, barium, iron, manganese, selenium), nitrate, benzene, toluene, ethylbenzene, xylene, methane, and the stable isotopic compositions of water and methane. Some portion of recharge to most of the wells for which data were available was derived from precipitation (most likely snowmelt), as indicated by δ2H [H2O] and δ18O[H2O] values that plot along the Global Meteoric Water Line and near the values for snow samples collected in the study area. Ninety-three percent of the samples were oxic, on the basis of concentrations of dissolved oxygen that were greater than or equal to 0.5 milligrams per liter. Concentration data were compared with primary and secondary drinking-water standards established by the U.S. Environmental Protection Agency. Constituents that exceeded the primary standards were arsenic (13 percent), selenium (9.2 percent), fluoride (8.4 percent), barium (4.1 percent), nitrate (1.6 percent), and benzene (0.6 percent). Concentrations of toluene, xylenes, and ethylbenzene did not exceed standards in any samples. Constituents that exceeded the secondary standard were dissolved solids (72 percent), sulfate (37 percent), manganese (21 percent), iron (16 percent), and chloride (10 percent). Drinking-water standards have not been established for methane, which was detected in 24 percent of samples. Methane concentrations were greater than or equal to 1 milligram per liter in 8.5 percent of samples. Methane isotopic data for samples collected primarily from domestic wells in Garfield County indicate that methane in samples with relative high methane concentrations were derived from both biogenic and thermogenic sources. Many of the constituents that exceeded standards, such as arsenic, fluoride, iron, and manganese, were derived from rock and sediment in aquifers. Elevated nitrate concentrations were most likely derived from human sources such as fertilizer and human or animal waste. Information about the geologic unit or aquifer in which a well was completed generally was not provided by data sources. However, limited data indicate that Quaternary deposits in Garfield and Mesa Counties, the Wasatch Formation in Garfield County, and the Green River Formation in Rio Blanco County had some of the highest median concentrations of selected constituents. Variations in concentration with depth could not be evaluated because of the general lack of well-depth and water-level data. Concentrations of several important constituents, such as arsenic, manganese, methane, and nitrate, were related to concentrations of dissolved oxygen. Concentrations of arsenic, manganese, and methane were significantly higher in groundwater with low dissolved-oxygen concentrations than in groundwater with high dissolved-oxygen concentrations. In contrast, concentrations of nitrate were significantly higher in groundwater with high dissolved-oxygen concentrations than in groundwater with low dissolved-oxygen concentrations. These results indicate that measurements of dissolved oxygen may be a useful indicator of groundwater vulnerability to some human-derived contaminants and enrichment from some natural constituents. Assessing such a large and diverse dataset as the one available through the repository poses unique challenges for reporting on groundwater quality in the study area. The repository contains data from several studies that differed widely in purpose and scope. In addition to this variability in available data, gaps exist spatially, temporally, and analytically in the repository. For example, groundwater-quality data in the repository were not evenly distributed throughout the study area. Several key water-quality constituents or indicators, such as dissolved oxygen, were underrepresented in the repository. Ancillary information, such as well depth, depth to water, and the geologic unit or aquifer in which a well was completed, was missing for more than 50 percent of samples. Future monitoring could avoid several limitations of the repository by making relatively minor changes to sample- collection and data-reporting protocols. Field measurements for dissolved oxygen could be added to sampling protocols, for example. Information on well construction and the geologic unit or aquifer in which a well was completed should be part of the water-quality dataset. Such changes would increase the comparability of data from different monitoring programs and also add value to each program individually and to that of the regional dataset as a whole. Other changes to monitoring programs could require greater resources, such as sampling for a basic set of constituents that is relevant to major water-quality issues in the regional study area. Creation of such a dataset for the regional study area would help to provide the kinds of information needed to characterize background conditions and the spatial and temporal variability in constituent concentrations associated with those conditions. Without such information, it is difficult to identify departures from background that might be associated with human activities.

Colorado↗
USGS2012

Palila abundance estimates and trend

The Palila (Loxioides bailleui) is an endangered, seed-eating, finch-billed honeycreeper found only on Hawai`i Island. Once occurring on the islands of Kaua`i and O`ahu and Mauna Loa and Hualālai volcanoes of Hawai`i, Palila are now found only in subalpine, dry-forest habitats on Mauna Kea (Banko et al. 2002). Previous analyses showed that Palila numbers fluctuated throughout the 1980s and 1990s but declined rapidly and steadily since 2003 (Jacobi et al. 1996, Leonard et al. 2008, Banko et al. 2009, Gorresen et al. 2009, Banko et al. in press). The aim of this report is to update abundance estimates for the Palila based on the 2012 surveys. We assess Palila trends over two periods: 1) the long-term trend during 1998–2012 and 2) the short-term trajectory between 2003 and 2012. The first period evaluates the population trend for the entire time series since additional transects were established (Johnson et al. 2006). These additional transects were established to produce a more precise population estimate and provide more complete coverage of the Palila range. The initial year for short-term trajectory was chosen subjectively to coincide with the recent decline in the Palila population. Additionally, stations in the core Palila habitat were surveyed on two occasions in 2012, thus allowing us to address the question of how repeat samples improve estimate precision.

Technical Report↗
USGS2024

Quantifying potential effects of China’s gallium and germanium export restrictions on the U.S. economy

China’s export controls on gallium and germanium exemplify concerns regarding the reliability of supplies of mineral commodities that are essential to economic development, national security, and transition to renewable energy. This report presents a new model that quantifies the potential effects of mineral commodity supply disruptions on the U.S. economy. After calculating postdisruption equilibrium prices and quantities, a nonlinear optimization routine was used along with economic input-output tables to estimate the effects of varying Chinese net export restrictions of gallium and germanium on U.S. gross domestic product (GDP). The results indicated that a complete restriction of China’s net exports of gallium and germanium could cause the U.S. GDP to decrease by $3.1 billion (with lower and upper estimates of $1.7 billion to $8.2 billion) and $0.4 billion ($0.01 billion to $1.1 billion), respectively, if disrupted separately, and $3.4 billion ($1.7 billion to $9.0 billion) if disrupted simultaneously. The proposed model can be applied to other commodities and disruption scenarios.

Open-File Report↗
USGS2005

Induction conductivity and natural gamma logs collected in 15 wells at Camp Stanley Storage Activity, Bexar County, Texas

The U.S. Geological Survey, in cooperation with the Camp Stanley Storage Activity conducted electromagnetic induction conductivity and natural gamma logging of 15 selected wells on the Camp Stanley Storage Activity, located in northern Bexar County, Texas, during March 28–30, 2005. In late 2004, a helicopter electromagnetic survey was flown of the Camp Stanley Storage Activity as part of a U.S. Geological Survey project to better define subsurface geologic units, the structure, and the catchment area of the Trinity aquifer. The electromagnetic induction conductivity and natural gamma log data in this report were collected to constrain the calculation of resistivity depth sections and to provide subsurface controls for interpretation of the helicopter electromagnetic data collected for the Camp Stanley Storage Activity. Logs were recorded digitally while moving the probe in an upward direction to maintain proper depth control. Logging speed was no greater than 30 feet per minute. During logging, a repeat section of at least 100 feet was recorded to check repeatability of log responses. Several of the wells logged were completed with polyvinyl chloride casing that can be penetrated by electromagnetic induction fields and allows conductivity measurement. However, some wells were constructed with steel centralizers and stainless steel screen that caused spikes on both conductivity and resulting resistivity log curves. These responses are easily recognizable and appear at regular intervals on several logs.

Texas↗
USGS1972

Summary of water resources of Salt Lake County, Utah

This report is a summary of a comprehensive report on the present water resources of Salt Lake County, Utah, and the potential for additional development The average total annual withdrawals from surface and underground sources during 1964-68 were about 580,000 acre-feet for all uses that deplete the supply, except that used for maintenance of waterfowl-management areas. The withdrawals projected for the year 2020 are 1,200,000 acre-feet. The maximum annual firm supply that can be derived from the sources now available is about 700,000 acre-feet, of which about 200,000 acre-feet would be derived from subsurface sources. Achievement of this annual yield would require nearly complete regulation of streamflow that now is practically unregulated, larger drawdowns of ground-water levels than have been experienced, and overall management of surface and subsurface sources as parts of a single resource.

Utah↗
USGS2004

Colonization, population growth, and nesting success of Black Oystercatchers following a seismic uplift

We present data on the colonization of Middleton Island, Alaska, by Black Oystercatchers ( Haematopus bachmani ) following the creation of an extensive rocky intertidal zone after the Alaskan earthquake of 1964. The first pair of oystercatchers was detected in 1976, and it was another 5 years before the population increased to three pairs. Oystercatcher numbers increased steadily thereafter, with a population explosion occurring in the 1990s. By 2002, there were 171 territorial pairs on the island. The total number of birds increased from two in 1976 to 718 in 2002. Breeding-pair densities on Middleton Island are the highest recorded for any portion of Alaska, averaging more than 5 pairs per km of shoreline in 2002. Nesting success in 2001 and 2002 was greater (83% or more of the eggs laid hatched) than that reported for any other population of oystercatchers in Alaska or along the Pacific Coast. We attribute this exponential growth rate and exceptionally high reproductive success to the large area of available and suitable habitat, the low number of avian predators and the complete lack of mammalian predators, low rate of nest loss to high tides and storm surges, and a low level of human disturbance. We propose nominating Middleton Island as a regional Western Hemisphere Shorebird Reserve Network site because a high percentage of the world's and region's population of Black Oystercatchers resides there during the breeding season. Further, since Middleton Island may be the single most important site in Alaska for Black Oystercatchers, we suggest it be protected from future development.

Alaska↗
USGS2018

Recommended nomenclature for zeolite minerals: Report of the subcommittee on zeolites of the International Mineralogical Association, Commission of New Minerals and Mineral Names

This report embodies recommendations on zeolite nomenclature approved by the International Mineralogical Association Commission of New Minerals and Mineral Names. In a working definition of a zeolite mineral used for review, interrupted tetrahedral framework structures are accepted where other zeolitic properties prevail, and complete substitution by elements other than Si and Al is allowed. Separate species are recognized in topologically distinctive compositional series in which different extra-framework cations are the most abundance in atomic proportions. To name these, the appropriate chemical symbol is attached by a hyphen to the series name as a suffix except for the names harmotome, pollucite and wairakite in the phillipsite and analcime series. Differences in space-group symmetry and in order-disorder relationships in zeolites having the same topologically distinctive framework do not in general provide adequate grounds for recognition of separate species. Zeolite species are not to be distinguished solely on Si:Al ratio except for heulandite (Si:Al < 4.0) and clinoptilolite ( Si : Al ⩾ 4.0 ). Dehydration, partial hydration, and over-hydration are not sufficient grounds for the recognition of separate species of zeolites. Use of the term 'ideal formula' should be avoided in referring to a simplified or averaged formula of a zeolite. Newly recognized species in compositional series are as follows: brewsterite-Sr.-Ba: chabazite-Ca.-Na.-K; clinoptilolite-K, -Na, -Ca: dachiardite-Ca, -Na; erionite-K, -Ca: faujasite-Na, -Ca, -Na: paulingite-K. -Ca; phillipsite-Na, -Ca, -Ka; stilbite-Ca, -Na. Key references, type locality, origin of name, chemical data. IZA structure-type symbols, space-group symmetry; unit-cell dimensions, and comments on structure are listed for 13 compositional series, 82 accepted zeolite mineral species, and three of doubtful status. Herschelite, leonhardite, svetlozarite, and wellsite are discredited as mineral species names. Obsolete and discredited names are listed.

Mineralogical Magazine↗
USGS2020

Describing historical habitat use of a native fish-Cisco (Coregonus artedi)-In Lake Michigan between 1930 and 1932

With the global-scale loss of biodiversity, current restoration programs have been often required as part of conservation plans for species richness and ecosystem integrity. The restoration of pelagic-oriented cisco ( Coregonus artedi ) has been an interest of Lake Michigan managers because it may increase the diversity and resilience of the fish assemblages and conserve the integrity of the ecosystems in a changing environment. To inform restoration, we described historical habitat use of cisco by analyzing a unique fishery-independent dataset collected in 1930–1932 by the U.S. Bureau of Fisheries’ first research vessel Fulmar and a commercial catch dataset reported by the State of Michigan in the same period, both based on gear fished on the bottom. Our results confirmed that the two major embayments, Green Bay and Grand Traverse Bay, were important habitats for cisco and suggest that cisco could complete the entire lifecycle within either of the Bays as there was no lack of summer feeding and fall spawning habitats. Seasonally, our results showed that cisco stayed in nearshore waters in spring, migrated to offshore waters in summer, and then migrated back to nearshore waters in fall for spawning. The results also suggest that in summer, most ciscoes were in waters with bottom depths of 20–70 m, but the highest cisco density occurred in waters with a bottom depth around 40 m. We highlight the importance of embayment habitats to cisco restoration and the seasonal migration pattern of cisco identified in this study, which suggests that a restored cisco population can diversify the food web by occupying different habitats from the exotic fishes that now dominate the pelagic waters of Lake Michigan.

Lake Michigan↗
USGS1999

How To Obtain Aerial Photographs

The U.S. Geological Survey (USGS) maintains an informational data base of aerial photographic coverage of the United States and its territories that dates back to the 1940?s. This information describes photographic projects from the USGS, other Federal, State, and local government agencies, and commercial firms. The pictures on this page show a part of a standard 9- by 9-inch photograph and the results obtained by enlarging the original photograph two and four times. Compare the size of the Qualcomm Stadium, Jack Murphy Field, in San Diego, Calif, and the adjacent parking lot and freeways shown at the different scales. USGS Earth Science Information Center (ESIC) representatives will assist you in locating and ordering photographs. Please submit the completed checklist and a marked map showing your area of interest to any ESIC.

Fact Sheet↗
USGS2015

LANDFIRE

LANDFIRE, also known as the Landscape Fire and Resource Management Planning Tools Program, is a vegetation, fire, and fuel characteristic mapping program managed by the U.S. Department of Agriculture Forest Service and the U.S. Department of the Interior. LANDFIRE represents the first, and only, complete, nationally consistent collection of spatial resource datasets with an ecological foundation that can be used across multiple disciplines. LANDFIRE data products are primarily designed and developed to be used at the landscape level to facilitate national and regional strategic planning and reporting of wild land fire and other natural resource management activities. However, LANDFIRE&rsquo;s spatially comprehensive dataset can also be adapted to support a variety of local management applications that need current and comprehensive geospatial data.

Fact Sheet↗
USGS1888

Geology of the quicksilver deposits of the Pacific slope, with an atlas

The field work of the investigations recorded in this volume occupied nearly the whole of three seasons, beginning in 1883. All the mines might have been examined and the maps colored in a much shorter time, but it was found soon after the examinations were begun that they could not be completed satisfactorily without also solving some important general problems affecting the whole region, and much of the time spent was devoted to these questions.

California↗
USGS1984

Geohydrologic data for test well USW G-4, Yucca Mountain area, Nye County, Nevada

Data are presented on drilling operations, lithology, borehole geophysics, hydrologic monitoring, core analysis, water chemistry, pumping tests, and packer-injection tests for test well USW G-4. The well is one of a series of test wells drilled in and near the southwestern part of the Nevada Test Site, Nye County, Nevada, in cooperation with the U.S. Department of Energy. These test wells are part of the Nevada Nuclear Waste Storage Investigations to identify suitable sites for underground storage of high-level radioactive wastes. Test well USW G-4 was drilled to a total depth of 915 meters through volcanic rocks, consisting mostly of ash-flow tuff. Depth of water in the well during and after drilling and testing ranged from 538 to 544 meters below land surface, at approximate altitude of 728 meters above sea level. Drawdown in the well was about 3 meters after test pumping more than 5,000 minutes at a rate of 16 liters per second. A borehold-flow survey indicated that almost all water withdrawn from the well was contributed by the zone between a depth of about 865 and 915 meters below land surface. Analysis of a composite water sample collected after well completion showed the water to contain 216 milligrams per liter of dissolved solids, with relatively large concentrations of silica, sodium, and bicarbonate. (USGS)

Open-File Report↗
USGS2026

Geologic framework, hydrostratigraphy, and ichnology of the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles, Blanco, Comal, Hays, and Kendall Counties, Texas

During 2023, the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, revised an initial characterization completed during 2015–16 of the geologic framework, hydrostratigraphy, and ichnology of the Edwards (Balcones Fault Zone) and Trinity aquifers in the Blanco, Payton, and Rough Hollow 7.5-minute quadrangles in Blanco, Comal, Hays, and Kendall Counties, Texas. The purpose of this report is to present the updated geologic framework, hydrostratigraphy, and ichnology of the Trinity and Edwards Groups in those quadrangles. Rocks exposed in the study area are of the Lower Cretaceous Trinity Group and lower part of the Fort Terrett Formation of the Lower Cretaceous Edwards Group. The faulting and fracturing in the study area are part of the Balcones Fault Zone, an extensional system of faults active during the Paleocene to middle Eocene that generally trends southwest to northeast in south-central Texas. Hydrostratigraphically, the rocks exposed in the study area contain a section of the Edwards (Balcones Fault Zone) aquifer, upper zone of the Trinity aquifer, and middle zone of the Trinity aquifer. In the study area, the only hydrostratigraphic units of the Edwards (Balcones Fault Zone) aquifer remaining are (from top to bottom) VII and VIII, which cap several hills. The mapped hydrostratigraphic units of the upper zone of the Trinity aquifer are (from top to bottom) the cavernous, Camp Bullis, upper evaporite, fossiliferous, and lower evaporite. The mapped hydrostratigraphic units of the middle zone of the Trinity aquifer are (from top to bottom) the Bulverde, Little Blanco, Twin Sisters, Doeppenschmidt, Herff Falls (where present), Rust, Honey Creek, Hensell, and Cow Creek hydrostratigraphic units.

Texas↗
USGS2009

Hydrology and simulation of ground-water flow in the Tooele Valley ground-water basin, Tooele County, Utah

Ground water is the sole source of drinking water within Tooele Valley. Transition from agriculture to residential land and water use necessitates additional understanding of water resources. The ground-water basin is conceptualized as a single interconnected hydrologic system consisting of the consolidated-rock mountains and adjoining unconsolidated basin-fill valleys. Within the basin fill, unconfined conditions exist along the valley margins and confined conditions exist in the central areas of the valleys. Transmissivity of the unconsolidated basin-fill aquifer ranges from 1,000 to 270,000 square feet per day. Within the consolidated rock of the mountains, ground-water flow largely is unconfined, though variability in geologic structure, stratigraphy, and lithology has created some areas where ground-water flow is confined. Hydraulic conductivity of the consolidated rock ranges from 0.003 to 100 feet per day. Ground water within the basin generally moves from the mountains toward the central and northern areas of Tooele Valley. Steep hydraulic gradients exist at Tooele Army Depot and near Erda. The estimated average annual ground-water recharge within the basin is 82,000 acre-feet per year. The primary source of recharge is precipitation in the mountains; other sources of recharge are irrigation water and streams. Recharge from precipitation was determined using the Basin Characterization Model. Estimated average annual ground-water discharge within the basin is 84,000 acre-feet per year. Discharge is to wells, springs, and drains, and by evapotranspiration. Water levels at wells within the basin indicate periods of increased recharge during 1983-84 and 1996-2000. During these periods annual precipitation at Tooele City exceeded the 1971-2000 annual average for consecutive years. The water with the lowest dissolved-solids concentrations exists in the mountain areas where most of the ground-water recharge occurs. The principal dissolved constituents are calcium and bicarbonate. Dissolved-solids concentration increases in the central and northern parts of Tooele Valley, at the distal ends of the ground-water flow paths. Increased concentration is due mainly to greater amounts of sodium and chloride. Deuterium and oxygen-18 values indicate water recharged primarily from precipitation occurs throughout the ground-water basin. Ground water with the highest percentage of recharge from irrigation exists along the eastern margin of Tooele Valley, indicating negligible recharge from the adjacent consolidated rock. Tritium and tritiogenic helium-3 concentrations indicate modern water exists along the flow paths originating in the Oquirrh Mountains between Settlement and Pass Canyons and extending between the steep hydraulic gradient areas at Tooele Army Depot and Erda. Pre-modern water exists in areas east of Erda and near Stansbury Park. Using the change in tritium along the flow paths originating in the Oquirrh Mountains, a first-order estimate of average linear ground-water velocity for the general area is roughly 2 to 5 feet per day. A numerical ground-water flow model was developed to simulate ground-water flow in the Tooele Valley ground-water basin and to test the conceptual understanding of the ground-water system. Simulating flow in consolidated rock allows recharge and withdrawal from wells in or near consolidated rock to be simulated more accurately. In general, the model accurately simulates water levels and water-level fluctuations and can be considered an adequate tool to help determine the valley-wide effects on water levels of additional ground-water withdrawal and changes in water use. The simulated increase in storage during a projection simulation using 2003 withdrawal rates and average recharge indicates that repeated years of average precipitation and recharge conditions do not completely restore the system after multiple years of below-normal precipitation. In the similar case where precipitation is 90

Utah↗
USGS2017

Fena Valley Reservoir watershed and water-balance model updates and expansion of watershed modeling to southern Guam

In 2014, the U.S. Geological Survey, in cooperation with the U.S. Department of Defense’s Strategic Environmental Research and Development Program, initiated a project to evaluate the potential impacts of projected climate-change on Department of Defense installations that rely on Guam’s water resources. A major task of that project was to develop a watershed model of southern Guam and a water-balance model for the Fena Valley Reservoir. The southern Guam watershed model provides a physically based tool to estimate surface-water availability in southern Guam. The U.S. Geological Survey’s Precipitation Runoff Modeling System, PRMS-IV, was used to construct the watershed model. The PRMS-IV code simulates different parts of the hydrologic cycle based on a set of user-defined modules. The southern Guam watershed model was constructed by updating a watershed model for the Fena Valley watersheds, and expanding the modeled area to include all of southern Guam. The Fena Valley watershed model was combined with a previously developed, but recently updated and recalibrated Fena Valley Reservoir water-balance model. Two important surface-water resources for the U.S. Navy and the citizens of Guam were modeled in this study; the extended model now includes the Ugum River watershed and improves upon the previous model of the Fena Valley watersheds. Surface water from the Ugum River watershed is diverted and treated for drinking water, and the Fena Valley watersheds feed the largest surface-water reservoir on Guam. The southern Guam watershed model performed “very good,” according to the criteria of Moriasi and others (2007), in the Ugum River watershed above Talofofo Falls with monthly Nash-Sutcliffe efficiency statistic values of 0.97 for the calibration period and 0.93 for the verification period (a value of 1.0 represents perfect model fit). In the Fena Valley watershed, monthly simulated streamflow volumes from the watershed model compared reasonably well with the measured values for the gaging stations on the Almagosa, Maulap, and Imong Rivers—tributaries to the Fena Valley Reservoir—with Nash-Sutcliffe efficiency values of 0.87 or higher. The southern Guam watershed model simulated the total volume of the critical dry season (January to May) streamflow for the entire simulation period within –0.54 percent at the Almagosa River, within 6.39 percent at the Maulap River, and within 6.06 percent at the Imong River. The recalibrated water-balance model of the Fena Valley Reservoir generally simulated monthly reservoir storage volume with reasonable accuracy. For the calibration and verification periods, errors in end-of-month reservoir-storage volume ranged from 6.04 percent (284.6 acre-feet or 92.7 million gallons) to –5.70 percent (–240.8 acre-feet or –78.5 million gallons). Monthly simulation bias ranged from –0.48 percent for the calibration period to 0.87 percent for the verification period; relative error ranged from –0.60 to 0.88 percent for the calibration and verification periods, respectively. The small bias indicated that the model did not consistently overestimate or underestimate reservoir storage volume. In the entirety of southern Guam, the watershed model has a “satisfactory” to “very good” rating when simulating monthly mean streamflow for all but one of the gaged watersheds during the verification period. The southern Guam watershed model uses a more sophisticated climate-distribution scheme than the older model to make use of the sparse climate data, as well as includes updated land-cover parameters and the capability to simulate closed depression areas. The new Fena Valley Reservoir water-balance model is useful as an updated tool to forecast short-term changes in the surface-water resources of Guam. Furthermore, the now spatially complete southern Guam watershed model can be used to evaluate changes in streamflow and recharge owing to climate or land-cover changes. These are substantial improvements to the previous models of the Fena Valley watershed and Reservoir. Datasets associated with this report are available as a U.S. Geological Survey data release (Rosa and Hay, 2017; DOI:10.5066/F7HH6HV4).

Scientific Investigations Report↗