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Rob Carruth

Publications and source records attributed to Rob Carruth.

10 recordsLinked to original sources
USGS2017

Hydrogeologic and geochemical characterization and evaluation of two arroyos for managed aquifer recharge by surface infiltration in the Pojoaque River Basin, Santa Fe County, New Mexico, 2014–15

In order to provide long-term storage of diverted surface water from the Rio Grande as part of the Aamodt water rights settlement, managed aquifer recharge by surface infiltration in Pojoaque River Basin arroyos was proposed as an option. The initial hydrogeologic and geochemical characterization of two arroyos located within the Pojoaque River Basin was performed in 2014 and 2015 in cooperation with the Bureau of Reclamation to evaluate the potential suitability of these two arroyos as sites for managed aquifer recharge through surface infiltration. The selected reaches were high-gradient (average 3.0–3.5 percent) braided channels filled with unconsolidated sand and gravel-sized deposits that were generally 30–50 feet thick. Saturation was not observed in the unconsolidated channel sands in four subsurface borings but was found at 7–60 feet below the contact between the unconsolidated channel sands and the bedrock. The poorly to well-cemented alluvial deposits that make up the bedrock underlying the unconsolidated channel material is the Tesuque Formation. The individual beds of the Tesuque Formation are reported to be highly heterogeneous and anisotropic, and the bedrock at the site was observed to have variable moisture and large changes in lithology. Surface electrical-resistivity geophysical survey methods showed a sharp contrast between the electrically resistive unconsolidated channel sands and the highly conductive bedrock; however, because of the high conductivity, the resistivity methods were not able to image the water table or preferential flow paths (if they existed) in the bedrock. Infiltration rates measured by double-ring and bulk infiltration tests on a variety of channel morphologies in the study reaches were extremely large (9.7–94.5 feet per day), indicating that the channels could potentially accommodate as much as 6.6 cubic feet per second of applied water without generating surface runoff out of the reach; however, the small volume available for storage in the unconsolidated channel sands (about 410 acre-feet in the east arroyo and about 190 acre-feet in the west arroyo) and the potential for the infiltrating water to preferentially flow over the bedrock contact and out of the reach present a challenge for storing water. Although a detailed assessment of the infiltration rate of the Tesuque Formation is beyond the scope of this investigation, one double-ring infiltrometer test was conducted on an outcrop, resulting in an estimated infiltration rate of about 4 feet per day. The shallow groundwater observed in this investigation was determined to be recharged locally on the basis of groundwater elevations and geochemical and isotopic signatures. The channel sands and shallow bedrock were observed to be weathered, indicating contact with oxic groundwater following deposition. This observation was supported by whole-rock elemental analysis and mineralogy of several core samples. The downward groundwater gradient between the shallow wells and those wells screened at greater depths suggests that the shallow groundwater is recharged by local precipitation and has the potential to migrate to the deeper aquifer units. The two age-dating tracers measured in this investigation, however, demonstrate that the shallow groundwater flow paths are very slow and that the deeper flow paths are likely part of a larger regional system. The composition of the shallow, native groundwater suggests that storing water diverted from the Rio Grande is not likely to leach constituents of concern that would cause the stored water to exceed health-based U.S. Environmental Protection Agency Maximum Contaminant Levels.

New Mexico↗
USGS2015

Surface and subsurface microgravity data in the vicinity of Sanford Underground Research Facility, Lead, South Dakota

Absolute gravity data were collected at 32 stations in the vicinity of the Sanford Underground Research Facility from 2007 through 2014 for the purpose of monitoring groundwater storage change during dewatering of the former Homestake gold mine in the Black Hills of South Dakota, the largest and deepest underground mine in North America. Eight underground stations are at depths from 300 feet below land surface to 4,850 feet below land surface. Surface stations were located using Global Positioning System observations, and subsurface stations were located on the basis of maps constructed from survey measurements made while the mine was in operation. Gravity varies widely at many stations; however, no consistent temporal trends are present across all stations during the 7-year period of data collection.

South Dakota↗
USGS2013

Qualilty, isotopes, and radiochemistry of water sampled from the Upper Moenkopi Village water-supply wells, Coconino County, Arizona

The Hopi Tribe Water Resources Program has granted contracts for studies to evaluate water supply conditions for the Moenkopi villages in Coconino County, Arizona. The Moenkopi villages include Upper Moenkopi Village and the village of Lower Moencopi, both on the Hopi Indian Reservation south of the Navajo community of Tuba City. These investigations have determined that water supplies are limited and vulnerable to several potential sources of contamination, including the Tuba City Landfill and a former uranium processing facility known as the Rare Metals Mill. Studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are greater than regional groundwater concentrations. The source of water supply for the Upper Moenkopi Village is three public-supply wells. The wells are referred to as MSW-1, MSW-2, and MSW-3 and all three wells obtain water from the regionally extensive N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and consists of thick beds of sandstone between less permeable layers of siltstone and mudstone. The relatively fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells. In recent years, water levels have declined in the three public-supply wells, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. Analyses of major ions, nutrients, selected trace metals, stable and radioactive isotopes, and radiochemistry were performed on the groundwater samples from the three public-supply wells to describe general water-quality conditions and groundwater ages in and immediately surrounding the Upper Moenkopi Village area. None of the water samples collected from the public-supply wells exceeded the U.S. Environmental Protection Agency primary drinking water standards. The ratios of the major dissolved ions from the samples collected from MSW-1 and MSW-2 indicate water with a major ion composition of calcium and sulfate. There is no significant vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column within the two wells. The samples collected at MSW-3 are higher in sodium and lower in calcium than the samples collected from MSW-1 and MSW-2, and contain a similar sulfate-ion percentage. There is a vertical distribution of ion concentrations in the samples collected from the upper and lower portion of the water column in MSW-3. Groundwater samples from the three water-supply wells analyzed for oxygen-18 and deuterium stable isotopes plot on a local water line that is approximately parallel to the global meteoric water line. Tritium concentrations in samples from MSW-1 and MSW-3 were equal to or less than laboratory detection limits and were interpreted to contain no modern (post-1952) water. Tritium concentration in a sample from the top of the water column at MSW-2 was 0.41 tritium units, indicating that the composition is primarily pre-bomb (pre-1952) water, but may contain a small fraction of post-bomb modern water. The calculated carbon-14 ages of groundwater in MSW-1 and MSW-2, both completed about 140 feet into the Navajo Sandstone, are about 3,000 years before present. The calculated carbon-14 age of groundwater in MSW-3, completed about 240 feet into the Kayenta Formation-Navajo Sandstone transition zone is about 5,000 years before present in the upper portion of the water column and about 8,500 years before present in the lower portion of the water column. The gross alpha radioactivity of samples collected from the three water-supply wells ranged from 5.1 to 9.8 picocuries per liter-less than the U.S. Environmental Protection Agency primary drinking water standard of 15 picocuries per liter. The gross beta radioactivity of samples collected from the wells ranged from 0.9 to 2.8 picocuries per liter and are not considered elevated relative to the U.S. Environmental Protection Agency primary drinking water standard.

Arizona↗
USGS2012

Aquifer test at well SMW-1 near Moenkopi, Arizona

The Hopi villages of Lower Moencopi and Upper Moenkopi are on the Hopi Indian Reservation south of Tuba City in northern Arizona. These adjacent Hopi villages, located west and north of the confluence of Pasture Canyon Wash and Moenkopi Wash, are dependent on groundwater withdrawals from three wells that penetrate the N aquifer and from two springs that discharge from the N aquifer. The N aquifer is the principal aquifer in this region of northern Arizona and is composed of thick beds of sandstone between less permeable layers of siltstone and mudstone. The fine-grained character of the N aquifer inhibits rapid movement of water and large yields to wells; however, the aquifer is moderately productive at yields generally less than 25 gallons per minute in the study area. In recent years, the water level has declined in the three public-supply wells and the flow from the springs has decreased, causing concern that the current water supply will not be able to accommodate peak demand and allow for residential and economic growth. In addition to the challenge imposed by declining groundwater levels, the water-supply wells and springs are located about 2 miles downgradient from the Tuba City Landfill site where studies are ongoing to determine if uranium and other metals in groundwater beneath the landfill are higher than regional concentrations in the N aquifer. In August 2008, the U.S. Geological Survey, in cooperation with the Hopi Tribe, conducted an aquifer test on well SMW-1, designed to help the Hopi Tribe determine the potential yield and water quality of the N aquifer south of Moenkopi Wash as a possible source of additional water supply. Well SMW-1 was drilled south of Moenkopi Wash to a depth of 760 feet below land surface before being backfilled and cased to about 300 feet. The well penetrates, in descending order, the Navajo Sandstone and the Kayenta Formation, both units of the N aquifer. The pre-test water level in the well was 99.15 feet below land surface. A 9.25-hour step-drawdown test and a 72-hour constant-rate test followed by recovery tests were used to investigate the performance of the test well and to estimate the transmissivity and potential yield of the N aquifer south of Moenkopi Wash. The test data were analyzed using the Cooper-Jacob method adjusted for confined conditions, the Papadopulos-Cooper method that accounts for wellbore storage, and the Theis method on the recovery data. Results of the tests indicate that in the vicinity of the well, the N aquifer has a transmissivity of about 50 feet squared per day. The test well, as completed, should yield about 15 gallons per minute with about 75 feet of drawdown (less than half of the available saturated thickness of the aquifer at the well).

Arizona↗
USGS2007

Land Subsidence and Aquifer-System Compaction in the Tucson Active Management Area, South-Central Arizona, 1987-2005

The U.S. Geological Survey monitors land subsidence and aquifer-system compaction caused by ground-water depletion in Tucson Basin and Avra Valley - two of the three alluvial basins within the Tucson Active Management Area. In spring 1987, the Global Positioning System was used to measure horizontal and vertical positions for bench marks at 43 sites to establish a network for monitoring land subsidence in Tucson Basin and Avra Valley. Between 1987 and 2005, the original number of subsidence monitoring stations was gradually increased to more than 100 stations to meet the need for information in the growing metropolitan area. Data from approximately 60 stations common to the Global Positioning System surveys done after an initial survey in 1987 are used to document land subsidence. For the periods of comparison, average land-surface deformation generally is less than the maximum subsidence at an individual station and takes into account land-surface recovery from elastic aquifer-system compaction. Between 1987 and 1998, as much as 3.2 inches of subsidence occurred in Tucson Basin and as much as 4 inches of subsidence occurred in Avra Valley. For the 31 stations that are common to both the 1987 and 1998 Global Positioning System surveys, the average subsidence during the 11-year period was about 0.5 inch in Tucson Basin and about 1.2 inches in Avra Valley. For the approximately 60 stations that are common to both the 1998 and 2002 Global Positioning System surveys, the data indicate that as much as 3.5 inches of subsidence occurred in Tucson Basin and as much as 1.1 inches of subsidence occurred in Avra Valley. The average subsidence for the 4-year period is about 0.4 inch in Tucson Basin and 0.6 inch in Avra Valley. Between the 2002 and the 2005 Global Positioning System surveys, the data indicate that as much as 0.2 inch of subsidence occurred in Tucson Basin and as much as 2.2 inches of subsidence occurred in Avra Valley. The average subsidence for the 3-year period is about 0.7 inch in Avra Valley. Between 1987 and 2004-05, land subsidence was greater in Avra Valley than in Tucson Basin on the basis of the average cumulative subsidence for the stations that were common to the original Global Positioning System survey in 1987. The average total subsidence during the 17- to 18-year period was about 1.3 inches in Tucson Basin and about 2.8 inches in Avra Valley. Three stations in Tucson Basin showed subsidence greater than 4 inches for the period - 5 inches at stations C45 and X419 and 4.1 inches at station PA4. In Avra Valley, two stations showed subsidence for the 17- to 18-year period greater than 4 inches - 4.3 inches at station AV25 and 4.8 inches at station SA105. In 1983, fourteen wells were fitted with borehole extensometers to monitor water-level fluctuations and aquifer-system compaction. Continuous records of water level and aquifer-system compaction indicate that as much as 45 feet of water-level decline and 4 inches of aquifer-system compaction occurred in Tucson Basin from January 1989 through December, 2005. In Avra Valley, extensometer data indicate that as much as 55 feet of water-level decline and 1.7 inches of aquifer-system compaction occurred during the same time period. Rates of compaction vary throughout the extensometer network, with the greater rates of compaction being associated with areas of greater water-level decline and more compressible sediments. In Avra Valley, data from the Global Positioning System surveys indicate that more than half of the total subsidence of the land surface may be the result of aquifer-system compaction below the portion of the aquifer instrumented with the vertical extensometers. For the area in the northern part of Tucson Basin between the Rillito and Santa Cruz rivers, an Interferometric Synthetic Aperture Radar interferogram indicates that about 1.65 inches of subsidence occurred between 2003 and 2006. Between 2002 and 2004, the Global Positioning System

Scientific Investigations Report↗
USGS2005

Construction, Geologic, and Hydrologic Data from Five Exploratory Wells on Rota, Commonwealth of the Northern Mariana Islands, 1999

Rota is the southernmost of the 14 small islands that make up the Commonwealth of the Northern Mariana Islands. Reduced springflow at Matan Hanom and As Onan springs occurred during a drought associated with the 1997-98 El Nino. Water from the two developed springs constituted the only municipal water source for the island at that time. In April 1998, reduced water supplies forced the Commonwealth Utilities Corporation to restrict water service in the principal villages of Songsong and Sinapalu for the duration of the dry season. In 1999, Five exploratory wells, EX-1 through EX-5 (CUC wells SP-MW1, SP-1, -2, -3, and SP-MW2), were drilled in the Sinapalu region of Rota to (1) assess the availability of fresh ground-water resources in an area where no other well information were available, and (2) to provide a new water source to help mitigate the impacts of drought associated with recurring El Nino weather events. The wells penetrated mainly light colored (dirty white to brownish), fragmental limestones containing abundant coral remains. Sustained-rate, recovery, and step-drawdown aquifer tests were attempted at each of the five exploratory wells to estimate aquifer properties in the vicinity of the wells and to assess the potential for new water sources. At wells EX-1 (CUC well SPMW1) and EX-5 (CUC well SP-MW2), attempts to conduct sustained-rate aquifer tests resulted in excessive drawdown to the pump intakes in the vicinity of the wells. At well EX-2 (CUC well SP-1), the maximum drawdown measured in the pumped well was 3.93 ft during 8 days of sustained pumping at an average rate of 187 gal/min. At well EX-3 (CUC well SP-2), the maximum drawdown measured in the pumped well was 2.31 ft during 8 days of sustained pumping at an average rate of 108 gal/min, and at well EX-4 (CUC well SP-3), the maximum drawdown measured in the pumped well was 3.27 ft during 8 days of sustained pumping at an average rate of 139 gal/min. Specific conductance at the end of 8 days of pumping was 403, 358, and 445 ?S/cm at well EX-2, EX-3, and EX-4 (CUC wells SP-1, -2, and -3), respectively.

Open-File Report↗
USGS2003

Ground-water resources of Saipan, Commonwealth of the Northern Mariana Islands

Saipan has an area of 48 mi 2 and is the largest of the 14 islands in the Commonwealth of the Northern Mariana Islands (CNMI). The island is formed by volcanic rocks overlain by younger limestones. The island is situated in the western Pacific Ocean at latitude 15 o 12'N and longitude 145 o 45'E, about 3,740 mi west-southwest of Honolulu and midway between Japan and New Guinea (fig. 1). The climate on Saipan is classified as tropical marine with an average temperature of 80 o F. The natural beauty of the island and surrounding waters are the basis for a growing tourist-based economy. The resulting rapid development and increases in resident and tourist populations have added stresses to the island's limited water supplies. Freshwater resources on Saipan are not readily observable because, aside from the abundant rainfall, most freshwater occurs as ground water. Fresh ground water is found in aquifers composed mainly of fragmental limestones. About 90 percent of the municipal water supply comes from 140 shallow wells that withdraw about 11 Mgal/d. The chloride concentration of water withdrawn from production wells ranges from less than 100 mg/L for wells in the Akgak and Capital Hill well fields, to over 2,000 mg/L from wells in the Puerto Rico, Maui IV, and Marpi Quarry well fields. The chloride concentrations and rates of ground-water production are not currently adequate for providing island residents with a potable 24-hour water supply and future demands are expected to be higher. To better understand the ground-water resources of the island, and water resources on tropical islands in general, the U.S. Geological Survey (USGS) entered into a cooperative program with the Commonwealth Utilities Corporation (CUC). The objective of the program, initiated in 1989, is to assess the ground-water resources of Saipan and to make hydrologic information available to the CUC in support of their ongoing efforts to improve the quality and quantity of the municipal water supply. This report presents some of the results of the program including descriptions of (1) the geography and geology, (2) the occurrence of fresh ground water in permeable limestones that extend to some distance below sea level where water-level elevation is affected by ocean tides (coastal aquifers) and in limestones that overlie volcanic basement rocks above sea level (high-level aquifers), (3) the water-table configuration and directions of ground-water flow, and (4) the rainfall, ground-water withdrawal, and chloride concentrations in well water. Also described is the relation of the changes in water-table elevations to changes in sea level, rainfall, and ground-water withdrawal.

Saipan↗
USGS2001

Hydrogeology of Picacho Basin, south-central Arizona

The hydrogeology of Picacho Basin was studied to define the stratigraphy, basin structure, physical and hydraulic properties of the basin sediments, and predevelopment and postdevelopment conditions of ground-water flow as of 1985. The study area includes about 900 square miles and contains a sedimentfilled asymmetric graben. The greatest sediment thickness occurs along the east margin of the graben. Basin sediments contain the principal water-bearing units and are separated into lower, middle, and upper units. The lower unit is several thousand feet thick and contains a conglomerate facies and a playa facies that contains a thick evaporite sequence. The middle and upper units contain alluvial and playa facies that are as much as 1,500 feet thick. Ground water occurs in lower and upper aquifer systems separated by a middle confining unit that comprises the playa facies of the three units. Hydraulic properties and compressibility of the middle and upper units are much greater than those of the lower unit. Vertical-head gradients exist, and vertical flow occurs within and between the aquifer systems. Early development of surface-water supplies resulted in increased recharge through deep percolation of irrigation water. Later development of the ground-water supplies resulted in extensive water-level declines, changes in the direction of ground-water flow, removal of water from storage, aquifer compaction, land subsidence, and earth fissures. Dewatering of pore spaces in the upper unit has been the primary source of water; however, as much as 80 percent of the water derived from storage in the Eloy area has resulted from compaction of pore spaces.

Arizona↗
USGS1998

Geology, Ground-Water Occurrence, and Estimated Well Yields from the Mariana Limestone, Kagman Area, Saipan, Commonwealth of the Northern Mariana Islands

A study of the geology, ground-water occurrence, and estimated well yields from the Mariana Limestone was done to investigate ground-water availability in the Kagman area, Saipan. The Mariana and Tagpochau Limestone formations form the major aquifer in the Kagman drainage basin. The Mariana Limestone, which is the major water-bearing unit in the Kagman area, ranges in thickness from 300 to 500 feet and contains intermittent, thin clay stringers. The calcareous rocks of the Tagpochau Limestone range in thickness from 500 to 1,000 feet and are more sandy than those of the Mariana Limestone. Ground water is unconfined in the Mariana Limestone and ranges from unconfined to confined in the Tagpochau Limestone. The fresh ground-water lens (that part of the lens with less than 2-percent of the chloride-ion concentration in seawater) in the Mariana Limestone is relatively thin, ranging from about 15 to 21 feet. Altitude of the water table ranges from about 1.5 to 2.5 feet above mean sea level. Freshwater in the Mariana Limestone is underlain by seawater and is separated by a transition zone about 8 to 25 feet thick. Hydraulic conductivity and transmissivity of the Mariana Limestone were calculated from data collected at six test wells. Using the Newman method, estimated hydraulic conductivity and transmissivity range from 290 to 2,500 feet per day and 7,600 to 62,000 feet squared per day, respectively. The higher values probably are indicative of average conditions in the Mariana Limestone. The estimated storage coefficient of the Mariana Limestone is about 0.1. The availability of water from the Mariana Limestone is restricted by the thinness of the freshwater lens. Results of the study indicate that fresh ground water can be obtained from the Mariana Limestone when wells are designed for minimum drawdown, effectively skimming freshwater from the top of the lens. Wells that are shallow, widely spaced, and pumped at low uniform rates can prevent saltwater intrusion. Calculated long-term yields of wells are about 30 gallons per minute or less for potable water.

Water-Resources Investigations Report↗