Geology topics

Susan A. Thiros

Publications and source records attributed to Susan A. Thiros.

29 records · Page 2Linked to original sources

USGS2003

Hydrogeology of shallow basin-fill deposits in areas of Salt Lake Valley, Salt Lake County, Utah

A study of recently developed residential/commercial areas of Salt Lake Valley, Utah, was done from 1999 to 2001 in areas in which shallow ground water has the potential to move to a deeper aquifer that is used for public supply. Thirty monitoring wells were drilled and sampled in 1999 as part of the study. The ground water was either under unconfined or confined conditions, depending on depth to water and the presence or absence of fine-grained deposits. The wells were completed in the shallowest water-bearing zone capable of supplying water. Monitoring-well depths range from 23 to 154 feet. Lithologic, geophysical, hydraulic-conductivity, transmissivity, water-level, and water-temperature data were obtained for or collected from the wells. Silt and clay layers noted on lithologic logs correlate with increases in electrical conductivity and natural gamma radiation shown on many of the electromagnetic-induction and natural gamma logs. Relatively large increases in electrical conductivity, determined from the electromagnetic-induction logs, with no major changes in natural gamma radiation are likely caused by increased dissolved-solids content in the ground water. Some intervals with high electrical conductivity correspond to areas in which water was present during drilling. Unconfined conditions were present at 7 of 20 monitoring wells on the west side and at 2 of 10 wells on the east side of Salt Lake Valley. Fine-grained deposits confine the ground water. Anthropogenic compounds were detected in water sampled from most of the wells, indicating a connection with the land surface. Data were collected from 20 of the monitoring wells to estimate the hydraulic conductivity and transmissivity of the shallow ground-water system. Hydraulic-conductivity values of the shallow aquifer ranged from 30 to 540 feet per day. Transmissivity values of the shallow aquifer ranged from 3 to 1,070 feet squared per day. There is a close linear relation between transmissivity determined from slug-test analysis and transmissivity estimated from specific capacity. Water-level fluctuations were measured in the 30 monitoring wells from 1999 to July 2001. Generally, water-level changes measured in wells on the west side of the valley followed a seasonal trend and wells on the east side showed less fluctuation or a gradual decline during the 2-year period. This may indicate that a larger percentage of recharge to the shallow ground-water system on the west side is from somewhat consistent seasonal sources, such as canals and unconsumed irrigation water, as compared to sources on the east side. Water levels measured in monitoring wells completed in the shallow ground-water system near large-capacity public-supply wells varied in response to ground-water withdrawals from the deeper confined aquifer. Water temperature was monitored in 23 wells. Generally, little or no change in water temperature was measured in monitoring wells with a depth to water greater than about 40 feet. The shallower the water level in the well, the greater the water-temperature change measured during the study. Comparison of water levels measured in the monitoring wells and deeper wells in the same area indicate a downward gradient on the east side of the valley. Water levels in the shallow and deeper aquifers in the secondary recharge area on the west side of the valley were similar to those on the east side. Water levels measured in the monitoring wells and nearby wells completed in the deeper aquifer indicate that the vertical gradient can change with time and stresses on the system.

Utah↗

USGS2002

Water-quality assessment of the Great Salt Lake basins, Utah, Idaho, and Wyoming: Environmental setting and study design

The Great Salt Lake Basins, Utah, Idaho, and Wyoming is one of 51 study units in the United States where the status and trends of water quality, and the factors controlling water quality, are being studied by the National Water-Quality Assessment Program of the U.S. Geological Survey. The 14,500-square-mile Great Salt Lake Basins study unit encompasses three major river systems that enter Great Salt Lake: the Bear, the Weber, and the Utah Lake/Jordan River systems. The environmental setting of the study unit includes natural and human-related factors that potentially influence the physical, chemical, and/or biological quality of the surface- and ground-water resources. Surface- and ground-water components of the planned assessment activities are designed to evaluate the sources of natural and human-related factors that affect the water quality in the Great Salt Lake Basins study unit.

Idaho, Utah, Wyoming↗

USGS2000

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

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

Idaho,Utah, Wyoming↗

USGS1999

Quality of shallow ground water in areas of recent residential and commercial development in Salt Lake Valley, Utah, 1999

R esidential and commercial development of about 80 square miles that primarily replaced undeveloped and agricultural areas occurred in Salt Lake Valley, Utah, from 1963 to 1994. The effects of human activities on the quality of shallow ground water in the recently developed areas were studied by the U.S. Geological Survey (USGS) as part of the National Water-Quality Assessment (NAWQA) program. The land-use study consisted of 30 monitoring wells installed and sampled in 1999 in residential/commercial areas where shallow ground water has the potential to move to a deeper public- supply aquifer. The water samples were analyzed for major ions, nutrients, pesticides, volatile organic compounds (VOCs), trace elements, and radon. The occurrence of nitrate, pesticides, and VOCs in water sampled from these wells can serve as an indicator of water affected by human activities at land surface. This report describes the nitrate, pesticide, and VOC data collected during the study.

Utah↗

USGS1999

Simulation of ground-water system response to proposed withdrawals from 1993 to 2043 in the northern part of Juab Valley, Juab County, Utah

Information on the ground-water system in the northern part of Juab Valley, Utah, is needed by water managers to plan the optimal use of surface water that will be imported by the Central Utah Project and ground water pumped locally. The response of the ground-water system to an increase in withdrawal with no new sources of recharge was simulated to provide a baseline for comparing possible water-management plans and to determine their potential effects on wetlands in the area. To assess the effects of additional withdrawal on the system, a 50-year-long stress period was added to the end of the existing three-dimensional, finite-difference, ground-water flow model. This stress period simulates recharge and discharge stresses determined for 1987-92. Another model was constructed by simulating 30 additional wells pumping a total of 4,000 acre-feet per year in the 50-year-long stress period. The 30 additional wells were simulated in a north-south trending line along the eastern part of the valley and as pumping from the bottom model layer. The difference between model-computed water-level changes after 10, 30, and 50 years with and without the additional pumped wells was calculated for the uppermost model layer. Water-level declines of more than 6 feet were computed for layer 1 in the area east of Mona Reservoir, and natural sources of ground-water discharge in the northern part of the valley decreased in response to 30 years of additional pumping. Discharge from springs and seeps computed in 2022 of the revised model simulating additional pumping decreased by about 7 percent and computed discharge by evapotranspiration decreased by about 23 percent relative to the same time in the revised model simulating no additional pumping.

Utah↗

USGS1996

Hydrology and simulation of ground-water flow in Juab Valley, Juab County, Utah.

Plans to import water to Juab Valley, Utah, primarily for irrigation, are part of the Central Utah Project. A better understanding of the hydrology of the valley is needed to help manage the water resources and to develop conjunctive-use plans. The saturated unconsolidated basin-fill deposits form the ground-water system in Juab Valley. Recharge is by seepage from streams, unconsumed irrigation water, and distribution systems; infiltration of precipitation; and subsurface inflow from consolidated rocks that surround the valley. Discharge is by wells, springs, seeps, evapotranspiration, and subsurface outflow to consolidated rocks. Ground-water pumpage is used to supplement surface water for irrigation in most of the valley and has altered the direction of groundwater flow from that of pre-ground-water development time in areas near and in Nephi and Levan. Greater-than-average precipitation during 1980-87 corresponds with a rise in water levels measured in most wells in the valley and the highest water level measured in some wells. Less-than average precipitation during 1988-91 corresponds with a decline in water levels measured during 1988-93 in most wells. Geochemical analyses indicate that the sources of dissolved ions in water sampled from the southern part of the valley are the Arapien Shale, evaporite deposits that occur in the unconsolidated basin-fill deposits, and possibly residual sea water that has undergone evaporation in unconsolidated basin-fill deposits in selected areas. Water discharging from a spring at Burriston Ponds is a mixture of about 70 percent ground water from a hypothesized flow path that extends downgradient from where Salt Creek enters Juab Valley and 30 percent from a hypothesized flow path from the base of the southern Wasatch Range. The ground-water system of Juab Valley was simulated by using the U.S. Geological Survey modular, three-dimensional, finite-difference, ground-water flow model. The numerical model was calibrated to simulate the steady-state conditions of 1949, multi-year transient-state conditions during 1949-92, and seasonal transient-state conditions during 1992-94. Calibration parameters were adjusted until model-computed water levels reasonably matched measured water levels. Parameters important to the calibration process include horizontal hydraulic conductivity, transmissivity, and the spatial distribution and amount of recharge from subsurface inflow and seepage from ephemeral streams to the east side of Juab Valley.

Utah↗

USGS1995

Chemical composition of ground water, hydrologic properties of basin-fill material, and ground-water movement in Salt Lake Valley, Utah

The chemical composition and movement of ground water and hydrologic properties of the basin‑fill material were studied to better under‑ stand the flow system in Salt Lake Valley, Utah. Recharge sources and water‑rock interactions influence the water chemistry in the principal and shallow unconfined aquifers. Chloride concentration in water from some wells has increased from the 1950’s and 1960’s to 1992, possibly because of the infiltration of water that contains dissolved road salt and the movement of ground water with relatively high chloride concentrations from volcanic rocks in the vicinity of these wells. Hydraulic‑conductivity values determined from slug tests done on wells finished in the shallow unconfined aquifer and confining layers ranged from 0.003 to 33.4 feet per day. Transmissivity values determined for the principal aquifer from four multiple‑well aquifer tests ranged from 6,400 to 43,600 feet squared per day. Vertical hydraulic‑conductivity values estimated from these tests are from 0.01 to 1 foot per day. Water from 81 sites was analyzed for the stable‑isotope ratios of oxygen and hydrogen to determine sources of recharge and mixing of water from these sources. Water sampled from the principal aquifer in the southeastern part of the valley is isotopically similar to water in Big and Little Cottonwood Creeks. Ground water sampled from the shallow unconfined aquifer is generally enriched in oxygen‑18 and deuterium relative to other water in the valley, except for water from the Jordan River and its diversions, which are probable recharge sources. Tritium concentrations ranging from about 33 to 59 tritium units in water from the principal aquifer in the southeastern part of the valley are representative of concentrations in water that was recharged in the 1960’s.

Utah↗

USGS1993

Ground-water hydrology of the upper Sevier River Basin, south-central Utah, and simulation of ground-water flow in the valley-fill in Panguitch Valley.

The ground-water hydrology of the upper Sevier River basin, primarily of the unconsolidated valley-fill aquifers, was studied from 1988 to 1989. Recharge to the valley-fill aquifers is mostly by seepage from surface-water sources. Changes in soil-moisture content am water levels were measured in Panguitch Valley both at a flood-irrigated and at a sprinkler-irrigated alfalfa field to quantify seepage from unconsumed irrigation water. Lag time between irrigation and water-level response decreased from 6 to 2 days in the flood-irrigated field as the soil-moisture content increased. Water levels measured in the sprinkler-irrigated field did not respond to irrigation. Discharge from the valley-fill aquifer to the Sevier River in Panguitch Valley is about 53,570 acre-feet per year. Water levels measured in wells from 1951 to 1989 tend to fluctuate with the quantity of precipitation falling at higher elevations. Ground-water discharge to the Sevier River in Panguitch Valley causes a general increase in the specific conductance of the river in a downstream direction. A three-layered ground-water-flow model was used to simulate the effects of changes in irrigation practices am increased ground-water withdrawals in Panguitch Valley. The establishment of initial conditions consisted of comparing simulated water levels and simulated gains and losses from the Sevier River and selected canals with values measured during the 1988 irrigation season. The model was calibrated by comparing water-level changes measured from 1961 to 1963 to simulated changes. A simulated change from flood to sprinkler irrigation resulted in a maximum decline in water level of 0.9 feet after the first year of change. Simulating additional discharge from wells resulted in drawdowns of about 20 feet after the first year of pumping.

Utah↗

USGS1992

Selected hydrologic data for Salt Lake Valley, Utah, 1990-92, with emphasis on data from the shallow unconfined aquifer and confining layers

Hydrologic data were collected from wells in the Salt Lake Valley, Utah, from 1990 to 1992, to better understand the hydrologic system in the valley. Most of the data collected are from 36 monitoring wells drilled in June and July 1990 and March and May 1991 using a hollow-stem auger. These wells range from 15.0 to 129.5 feet deep and are completed in the shallow unconfined aquifer, an underlying confining layer, or both. Data from public supply wells and other existing wells completed in aquifers below the confining layers near these monitoring wells are presented in order to compare data from those wells with data from the shallow unconfined aquifer and the underlying confining layers. Field data collected from selected wells and drill holes include well-completion information, lithologic logs, and water-level and field water-quality measurements. Water samples collected from monitoring wells drilled in 1990 and 1991 and from selected existing wells were analyzed for inorganic constituents, trace metals in unfiltered water, volatile organic compounds, organochlorine pesticides, polychlorinated biphenyls, and radionuclides. Core samples were collected from selected monitoring wells drilled in 1990 and 1991 and analyzed for geochemical and geotechnical properties. Cation exchange capacity, carbon concentration, and the concentration of selected elements in core material are presented. Particle size, dry density, moisture content, porosity, hydraulic conductivity, initial void ratio, specific storage, and other properties determined for material in cores from selected monitoring wells also are listed.

Utah↗

USGS1988

Selected hydrologic data for Pahvant Valley and adjacent areas, Millard County, Utah, 1987

This report contains hydrologic data collected in Pahvant Valley and adjacent areas from 1909 to 1987. The report area is mainly comprised of Pahvant Valley on the east and the southern part of the Sevier Desert on the west (plate 1). The area is in west-central Utah, within the Basin and Range physiographic province, and includes about 1,600 square miles. Most of the data in this report were collected by the U.S. Geological Survey in cooperation with the Utah Department of Natural Resources, Division of Water Rights, from 1985 to 1987. Some of the earlier data were previously published by Enright and Holmes (1982), Meinzer (1911), Mower (1963 and 1967), and Mundorff (1970). The purpose of this report is to provide hydrologic data for use by the general public and by officials managing the area's water resources, and to supplement interpretive reports for the area. Tables 1 to 6 contain information about wells including well completions, drillers' logs, water levels, flowing-well discharges, and chemical quality. Spring and surfacewater site data are listed in tables 7 to 9. Hydrologic-data sites are shown on plate 1.

Utah↗

USGS1988

Developing a state water plan: Ground-water conditions in Utah, spring of 1988

This is the twenty-fifth in a series of annual reports that describe ground-water conditions in Utah. Reports in this series, published cooperatively by the U.S. Geological Survey and the Utah Division of Water Resources, provide data to enable interested parties to keep abreast of changing ground-water conditions. This report, like the others in the series, contains information on well construction, ground-water withdrawals from wells, water-level changes, and related changes in precipitation and streamflow. Supplementary data such as graphs showing chemical quality of water and maps showing water-level contours are included in reports of this series only for those years or areas for which applicable data are available and are important to a discussion of changing ground-water conditions. This report includes individual discussions of selected major areas of ground-water development in the State for the calendar year 1987. Water-level fluctuations, however, are described from the spring of 1987 to the spring of 1988. Much of the data used in this report were collected by the U.S. Geological Survey in cooperation with the Division of Water Rights, Utah Department of Natural Resources.

Utah↗