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At least 1,261 records · Page 70Linked to original sources
USGS2002

Water quality and geochemical modeling of water at an abandoned coal mine reclaimed With coal combustion by-products

An abandoned coal mine in eastern Ohio was reclaimed with 125 tons per acre of pressurized fluidized bed combustion (PFBC) by-product. Water quality at the site (known as the Fleming site) was monitored for 7 years after reclamation; samples included water from soil-suction lysimeters (interstitial water), wells, and spring sites established downgradient of the application area. This report presents a summary of data collected at the Fleming site during the period September 1994 through June 2001. Additionally, results of geochemical modeling are included in this report to evaluate the potential fate of elements derived from the PFBC by-product. Chemical analyses of samples of interstitial waters within the PFBC by-product application area indicated elevated levels of pH and specific conductance and elevated concentrations of boron, calcium, chloride, fluoride, magnesium, potassium, strontium, and sulfate compared to water samples collected in a control area where traditional reclamation methods were used. Magnesium-to-calcium (Mg:Ca) mole ratios and sulfur-isotope ratios were used to trace the PFBC by-product leachate and showed that little, if any, leachate reached ground water. Concentrations of most constituents in interstitial waters in the application-area decreased during the seven sampling rounds and approached background concentrations observed in the control area; however, median pH in the application area remained above 6, indicating that some acid-neutralizing capacity was still present. Although notable changes in water quality were observed in interstitial waters during the study period, quality of ground water and spring water remained poor. Water from the Fleming site was not potable, given exceedances of primary and secondary Maximum Contaminant Levels (MCLs) for inorganic constituents in drinking water set by the U.S. Environmental Protection Agency. Only fluoride and sulfate, which were found in higher concentrations in application-area interstitial waters than in control-area interstitial waters, could be related to the PFBC by-product. Concentrations of arsenic, lead, and selenium typically were at or below the detection limits (generally 1 or 2 micrograms per liter). Elements detected at elevated concentrations in PFBC by-product application-area interstitial waters were not evident in downgradient ground water or spring water. Dilution of leachate by ground water was confirmed with a mixing model generated by the computer code NETPATH. Additionally, thermodynamic modeling of the chemical composition of water samples by use of the computer code PHREEQC indicated favorable conditions for precipitation of secondary minerals in the unsaturated zone and in aquifer materials. Because of low application rates of PFBC by-product and precipitation and sorption of elements in the unsaturated zone, it is improbable that concentrations of any toxic elements of concern (arsenic, lead, or selenium) will exceed drinking-water standards at this site or other sites where similar volumes of PFBC by-products are used.

Water-Resources Investigations Report↗
USGS2001

Ground-water quality in Geauga County, Ohio — Review of previous studies, status in 1999, and comparison of 1986 and 1999 data

Most residents in Geauga County, Ohio, rely on ground water as their primary source of drinking water. With population growing at a steady rate, the possibility that human activity will affect ground-water quality becomes considerable. This report presents the results of a study by the U.S. Geological Survey (USGS), in cooperation with the Geauga County Planning Commission and Board of County Commissioners, to provide a brief synopsis of work previously done within the county, to assess the present (1999) ground-water quality, and to determine any changes in groundwater quality between 1986 and 1999. Previous studies of ground-water quality in the county have consistently reported that manganese and iron concentrations in ground water in Geauga County often exceed the U.S. Environmental Protection Agency (USEPA) Secondary Maximum Contaminant Level (SMCL). Road salt and, less commonly, oil-field brines and volatile organic compounds (VOCs) have been found in ground water at isolated locations. Nitrate has not been detected above the USEPA Maximum Contaminant Level (MCL) of 10 milligrams per liter as N; however, nitrate has been found in some locations at levels that may indicate the effects of fertilizer application or effluent from septic systems. Between June 7 and July 1, 1999, USGS personnel collected a total of 31 water-quality samples from wells completed in glacial deposits, the Pottsville Formation, the Cuyahoga Group, and the Berea Sandstone. All samples were analyzed for VOCs, sulfide, dissolved organic carbon, major ions, trace elements, alkalinity, total coliforms, and Escherichia coli bacteria. Fourteen of the samples also were analyzed for tritium. Water-quality data were used to determine (1) suitability of water for drinking, (2) age of ground water, (3) stratigraphic variation in water quality, (4) controls on water quality, and (5) temporal variation in water quality. Water from 16 of the 31 samples exceeded the Geauga County General Health District’s standard of 0 colonies of total coliform bacteria per 100 milliliters of water. Esthetically based SMCLs were exceeded in the indicated number of wells for pH (8), sulfate (1), dissolved solids (3), iron (19), and manganese (18). Hydrogen sulfide was detected at or above the detection limit of 0.01 milligram per liter in 17 of the 31 water samples. A range of water types was found among and within the four principal stratigraphic units. The waters can be categorized in three groups based on predominant anion type: bicarbonatetype waters, chloride-type waters, and sulfatetype waters. Chloride-to-bromide ratio analyses indicate that water from 8 of the 31 wells is in some way affected by human activity. Five other samples were in a chloride-to-bromide ratio range that could indicate possible effects of human activity. Ground-water-quality data from the current study were compared to data collected in 1986. Statistical analyses of data from the 16 wells that were sampled in both years did not indicate any significant changes that could be attributed to human activity.

Ohio↗
USGS2003

Ground-Water Quality and its Relation to Land Use on Oahu, Hawaii, 2000-01

Water quality in the main drinking-water source aquifers of Oahu was assessed by a one-time sampling of untreated ground water from 30 public-supply wells and 15 monitoring wells. The 384 square-mile study area, which includes urban Honolulu and large tracts of forested, agricultural, and suburban residential lands in central Oahu, accounts for 93 percent of the island's ground-water withdrawals. Organic compounds were detected in 73 percent of public-supply wells, but mostly at low concentrations below minimum reporting levels. Concentrations exceeded drinking-water standards in just a few cases: the solvent trichloroethene and the radionuclide radon-222 exceeded Federal standards in one public-supply well each, and the fumigants 1,2-dibromo-3-chloropropane (DBCP) and 1,2,3-trichloropropane (TCP) exceeded State standards in three public-supply wells each. Solvents, fumigants, trihalomethanes, and herbicides were prevalent (detected in more than 30 percent of samples) but gasoline components and insecticides were detected in few wells. Most water samples contained complex mixtures of organic compounds: multiple solvents, fumigants, or herbicides, and in some cases compounds from two or all three of these classes. Characteristic suites of chemicals were associated with particular land uses and geographic locales. Solvents were associated with central Oahu urban-military lands whereas fumigants, herbicides, and fertilizer nutrients were associated with central Oahu agricultural lands. Somewhat unexpectedly, little contamination was detected in Honolulu where urban density is highest, most likely as a consequence of sound land-use planning, favorable aquifer structure, and less intensive application of chemicals (or of less mobile chemicals) over recharge zones in comparison to agricultural areas. For the most part, organic and nutrient contamination appear to reflect decades-old releases and former land use. Most ground-water ages were decades old, with recharge dates ranging from pre-1940 to the present, and with most dates falling within the 1950s to 1980s time span. Several widely detected compounds were discontinued as long ago as the 1970s but have yet to be flushed from the ground-water system. Although large tracts of land in central Oahu have been converted from agriculture to residential urban use since the 1950s, water quality in the converted areas still more closely reflects the former agricultural land. It appears to be too early to detect a distinct water-quality signature characteristic of the newer urban use, although several urban turfgrass herbicides in use for just 10 years or so were detected in monitoring wells and may represent early arrivals of urban contaminants at the water table.

Water-Resources Investigations Report↗
USGS2000

A three-dimensional finite-volume Eulerian-Lagrangian Localized Adjoint Method (ELLAM) for solute-transport modeling

This report documents the U.S. Geological Survey Eulerian-Lagrangian Localized Adjoint Method (ELLAM) algorithm that solves an integral form of the solute-transport equation, incorporating an implicit-in-time difference approximation for the dispersive and sink terms. Like the algorithm in the original version of the U.S. Geological Survey MOC3D transport model, ELLAM uses a method of characteristics approach to solve the transport equation on the basis of the velocity field. The ELLAM algorithm, however, is based on an integral formulation of conservation of mass and uses appropriate numerical techniques to obtain global conservation of mass. The implicit procedure eliminates several stability criteria required for an explicit formulation. Consequently, ELLAM allows large transport time increments to be used. ELLAM can produce qualitatively good results using a small number of transport time steps. A description of the ELLAM numerical method, the data-input requirements and output options, and the results of simulator testing and evaluation are presented. The ELLAM algorithm was evaluated for the same set of problems used to test and evaluate Version 1 and Version 2 of MOC3D. These test results indicate that ELLAM offers a viable alternative to the explicit and implicit solvers in MOC3D. Its use is desirable when mass balance is imperative or a fast, qualitative model result is needed. Although accurate solutions can be generated using ELLAM, its efficiency relative to the two previously documented solution algorithms is problem dependent.

Water-Resources Investigations Report↗
USGS1982

Water-quality assessment of Steiner Branch basin, Lafayette County, Wisconsin

Steiner Branch basin in southwestern Wisconsin has rugged mature topography. Corn is planted in 30 percent of the basin on slopes ranging from 0 to 20 percent. Although contour stripcropping is a recommended practice for these easily eroded soil slopes, few conservation practices are followed to reduce soil losses. Because the stream drains into a manmade lake used for recreation, its water quality is of major concern. The purpose of this report is to assess the magnitude and types of nonpoint discharges that affect the water quality of Steiner Branch. Total stream discharge for the 1978 and 1979 water years was 1,500 cubic feet per second per day and 1,800 cubic feet per second per day, respectively. The 1978 water year discharge was about 90 percent of the average and the 1979 discharge was 120 percent of average. During the 1978 water year, base flow was about 60 percent of the stream discharge, and in 1979 it was about 78 percent. Streamflow during the 2-year study period ranged from 1.5 cubic feet per second, which is approximately the low flow that occurs on the average of once every 2 years, to 392 cubic feet per second, a discharge of about a 5-year flood-recurrence interval. Suspended-sediment yields were 369 tons per square mile in the 1978 water year and 84.6 tons per square mile in 1979. These yields were 1.66 times higher than those monitored in an adjoining basin where more typical conservation practices were employed. However, suspended-sediment yield per unit of stream discharge was only 1.30 times higher in the Steiner Branch basin than in the adjoining basin. The estimated long-term annual suspended-sediment yield for the Steiner Branch basin is 444 tons per square mile. Sediment concentrations in Steiner Branch ranged from 3 to 6,430 milligrams per liter. Most of the nutrient load of the stream was transported during runoff: total organic nitrogen, 80 percent; ammonia nitrogen, 80 percent; total phosphorus, 84 percent; and total orthophosphorus, 77 percent. Transport of nitrite plus nitrate nitrogen and total nitrogen occurred primarily during baseflow conditions, with 75 and 56 percent, respectively, of the total load for the study period being transported during these conditions. The time distribution of total phosphorus, total orthophosphorus, ammonia nitrogen, and total organic nitrogen transport was very similar to suspended-sediment transport in Steiner Branch.

Wisconsin↗
USGS2001

Soil analyses for 1,3-dichloropropene (1,3-DCP), sodium n-methyldithiocarbamate (metam-sodium), and their degradation products near Fort Hall Idaho, September 1999 through March 2000

Between September 1999 and March 2000, soil samples from the Fort Hall, Idaho, area were analyzed for two soil fumigants, 1,3-dichloropropene (1,3-DCP) and sodium n-methyldithiocarbamate (metam-sodium), and their degradation products. Ground water is the only source of drinking water at Fort Hall, and the purpose of the investigation was to determine potential risk of ground-water contamination from persistence and movement of these pesticides in cropland soils. 1,3-DCP, metam-sodium, or their degradation products were detected in 42 of 104 soil samples. The samples were collected from 1-, 2-, and 3-foot depths in multiple backhoe trenches during four sampling events—before pesticide application in September; after application in October; before soil freeze in December; and after soil thaw in March. In most cases, concentrations of the pesticide compounds were at or near their laboratory minimum reporting limits. U.S. Environmental Protection Agency Method 5035 was used as the guideline for soil sample preparation and analyses, and either sodium bisulfate (NaHSO4), an acidic preservative, or pesticide-free water was added to samples prior to analyses. Addition of NaHSO4 to the samples resulted in a greater number of compound detections, but pesticide-free water was added to most samples to avoid the strong reactions of soil carbonate minerals with the NaHSO4. As a result, nondetection of compounds in samples containing pesticide-free water did not necessarily indicate that the compounds were absent. Detections of these compounds were inconsistent among trenches with similar soil characteristics and histories of soil fumigant use. Compounds were detected at different depths and different trench locations during each sampling event. Overall results of this study showed that the original compounds or their degradation products can persist in soil 6 months or more after their application and are present to at least 3 feet below land surface in some areas. A few of the soil analyses results were unexpected. Degradation products of metam-sodium were detected in samples from croplands with a history of 1,3-DCP applications only, and were not detected in samples from croplands with a history of metam-sodium applications. Although 1,2-dibromoethane (EDB) has not been used in the area for many years, EDB was detected in a few soil samples. The presence of EDB in soil could be caused by irrigation of croplands with EDBcontaminated ground water. Analyses of these soil samples resulted in many unanswered questions, and further studies are needed. One potential study to determine vertical extent of pesticide compound migration in sediments, for example, would include analysis of one or more columns of soil and sediments (land surface to ground water, about 35 to 50 feet below land surface) in areas with known soil contamination. Another study would expand the scope of soil contamination to include broader types of cropland conditions and compound analyses.

Idaho↗
USGS1996

Streambed-material characteristics and surface-water quality, Green Pond Brook and tributaries, Picatinny Arsenal, New Jersey, 1983-90

This report presents the results of a study conducted at Picatinny Arsenal, Morris County, New Jersey, to (1) determine whether streambed sediments in Green Pond Brook and its tributaries are contaminated with inorganic or organic constituents, (2) determine the extent of contamination in those reaches, and (3) characterize the quality of water in the brook. Shallow auger samples and results of an electromagnetic-conductivity and natural-gamma-ray survey were used to describe the distribution of streambed and substreambed sediment types and particle sizes. Forty-five streambed samples were analyzed for trace elements, base/neutral- and acid-extractable compounds, organochlorine and organophosphorus insecticides, polychlorinated biphenyls, and polychlorinated naphthalenes to determine whether contaminants have migrated to the brook from the surrounding area. Historical results of analyses of 63 surface-water and 27 streambed samples also are presented. Samples of streambed material collected from three areas in Green Pond Brook and its tributaries Green Pond Brook, from the area near the outflow of Picatinny Lake downstream to Parley Avenue; Bear Swamp Brook, from the area near building 241 downstream to the confluence with Green Pond Brook; and Green Pond Brook, from the open burning area downstream to the dam near building 1178 contained organic and (or) inorganic constituents in concentrations greater than those found under natural conditions and greater than those found in other areas sampled at the arsenal. Contaminants identified include trace elements, polynuclear aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine insecticides. Surface-water samples from Green Pond Brook contained several volatile organic compounds, including trichloroethylene, tetrachloroethylene, and 1,2-dichloroethylene, at maximum concentrations of 3.8,4.6, and 11 micrograms per liter, respectively. Volatilization and dilution by surface- water and ground-water inflow reduce concentrations of volatile organic compounds from surface water in the steep, fast-flowing reaches of the brook at the southern end of the arsenal. No organic or inorganic constituents were detected in surface-water samples in concentrations greater than the U.S. Environmental Protection Agency primary drinking-water regulations. Only two constituents, iron and manganese, were detected in concentrations greater than the U.S. Environmental Protection Agency secondary drinking-water regulations.

New Jersey↗
USGS1978

Low-flow frequency of Georgia streams

This report contains analyses of low-flow data and tabulations of computed low-flow frequency for all stream sites in Georgia where suitable flow records have been collected. These include 134 continuous-record gaging stations and 102 partial-record gaging stations. Frequency records for gaging stations with short records have been adjusted where possible to more closely represent results that would have been obtained from longer records. Variations in time and place of low-flow characteristics, per unit of drainage area, are demonstrated. Low flows for 7 consecutive days with a 10-year recurrence interval vary from 0 to more than 1.0 cubic feet per second per square mile [(ft 3 /s)/mi 2 ]. In the Blue Ridge province in the northern part of the State, unit low flows range from 0.3 to 0.8 (ft 3 /s)/mi 2 ; in the Valley and Ridge province in the northwest they range from 0.05 to 0.04 (ft 3 /s)/mi 2 ; and in the Piedmont province they range from 0.1 to 1.1 (ft 3 /s)/mi 2 . There is a contrast in unit rates of low flow between the upper zone of the Coastal Plain where most flows are high, and the lower zone where most flows are low. Flows in the upper zone are in the range of 0.1 to 1.1 (ft 3 /s)/mi 2 , but in the lower zone only the largest streams have appreciable flow during low-flow periods.

Georgia↗
USGS1997

Field screening of water quality, bottom sediment, and biota associated with irrigation drainage in the Yuma Valley, Arizona, 1995

Because of concerns expressed by the U.S. Congress and the environmental community, the Department of the Interior began a program in late 1985 to identify the nature and extent of water-quality problems induced by irrigation that might exist in the western States. Surface water, bottom sediment, and biota were collected from March through September 1995 along the lower Colorado River and in agricultural drains at nine sites in the Yuma Valley, Arizona, and analyzed for selected inorganic and organic constituents. Analyses of water, bottom sediment, and biota were completed to determine if irrigation return flow has caused, or has the potential to cause, harmful effects on human health, fish, and wildlife in the study area. Concentrations of dissolved solids in surface-water samples collected in March generally did not vary substantially from surface-water samples collected in June. Concentrations of dissolved solids ranged from 712 to 3,000 milligrams per liter and exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 500 milligrams per liter for drinking water. Concentrations of chloride in 9 of 18 water samples and concentrations of sulfate in 16 of 18 water samples exceeded the U.S. Environmental Protection Agency secondary maximum contaminant level of 250 milligrams per liter for drinking water. Calcium and sodium were the dominant cations, and chloride and sulfate were the dominant anions. The maximum selenium concentration of 8 micrograms per liter exceeded the U.S. Environmental Protection Agency aquatic-life chronic criterion of 5 micrograms per liter. Concentrations of lead in 7 of 18 water samples and concentrations of mercury in 4 of 18 water samples exceeded the aquatic-life cronic criteria of 3.2 and 0.012 micrograms per liter, respectively. Concentrations of antimony, beryllium, cadmium, and silver in the water samples were below analytical reporting limits. Arsenic was detected in 3 of 9 bottom-sediment samples, and concentrations ranged from 11 to 16 micrograms per gram. Concentrations ofaluminum, beryllium, boron, copper, lead, and zinc were highest in samples from Main Drain at southerly international boundary near San Luis, Arizona. Selenium was detected in all bottom-sediment samples, and concentrations ranged from 0.1 to 0.7 micrograms per gram. Concentrations of cadmium, europium, homium, mercury, molybdenum, silver, tantalum, tin, and uranium were below analytical reporting limits in the bottom-sediment samples. Concentrations of trace elements in bottom-sediment samples were within the ranges found in a study of soils of the western United States and did not indicate a significant accumulation of these constituents. p,p'Dichlorodiphenyldichloroethylene (commonly referred to as p,-p'-DDE) was detected in one bottom-sediment sample at a concentration of 1.4 micrograms per gram. No other organochlorine compounds were detected in the bottom-sediment samples. DDE was present in all fish and bird samples. Almost one-half of the fish samples contained DDE residues that were two times higher than the mean calculated for a national study in 1984-85. Twenty-tree percent of the fish contained more than three times the national mean. Fish from downstream parts of the Main Drain had the highest concentrations of DDE. Although concentrations of DDE in fish and in bird carcasses and eggs were above background levels, residues generally were below thresholds associated with chronic poisoning and reproductive problems in figh and wildlife. Concentrations of 18 trace elements were detected in cattail (Typha sp.) roots, freshwater clam (Corbicula fluminea), fish, and bird samples. Selenium in most fish and in livers of red-winged (Agelaius phoeniceus) and yellow-headed (Xanthocephalus xanthocephalus) blackbirds was above background concentrations but below toxic concentrations. In contrast, selenium was present in a killdeer (Charadrium vociferus) liver sample at potentially toxic con

Water-Resources Investigations Report↗
USGS1987

Estimates of average annual tributary inflow to the lower Colorado River, Hoover Dam to Mexico

Estimates of tributary inflow by basin or area and by surface water or groundwater are presented in this report and itemized by subreaches in tabular form. Total estimated average annual tributary inflow to the Colorado River between Hoover Dam and Mexico, excluding the measured tributaries, is 96,000 acre-ft or about 1% of the 7.5 million acre-ft/yr of Colorado River water apportioned to the States in the lower Colorado River basin. About 62% of the tributary inflow originates in Arizona, 30% in California, and 8% in Nevada. Tributary inflow is a small component in the water budget for the river. Most of the quantities of unmeasured tributary inflow were estimated in previous studies and were based on mean annual precipitation for 1931-60. Because mean annual precipitation for 1951-80 did not differ significantly from that of 1931-60, these tributary inflow estimates are assumed to be valid for use in 1984. Measured average annual runoff per unit drainage area on the Bill Williams River has remained the same. Surface water inflow from unmeasured tributaries is infrequent and is not captured in surface reservoirs in any of the States; it flows to the Colorado River gaging stations. Estimates of groundwater inflow to the Colorad River valley. Average annual runoff can be used in a water budget; although in wet years, runoff may be large enough to affect the calculation of consumptive use and to be estimated from hydrographs for the Colorado River valley are based on groundwater recharge estimates in the bordering areas, which have not significantly changed through time. In most areas adjacent to the Colorado River valley, groundwater pumpage is small and pumping has not significantly affected the quantity of groundwater discharged to the Colorado River valley. In some areas where groundwater pumpage exceeds the quantity of groundwater discharge and water levels have declined, the quantity of discharge probably has decreased and groundwater inflow to the Colorado River valley will eventually be reduced if not stopped completely. Groundwater discharged at springs below Hoover Dam is unused and flows directly to the Colorado River. (Lantz-PTT)

Water-Resources Investigations Report↗
USGS2001

Evaluation of the streamflow-gaging network of Texas and a proposed core network

The U.S. Geological Survey streamflowgaging network in Texas is operated as part of the National Streamgaging Program and is jointly funded by the Geological Survey and Federal, State, and local agencies. This report documents an evaluation of the existing (as of October 1, 1999) network with regard to four major objectives of streamflow data; and on the basis of that evaluation, proposes a core network of streamflowgaging stations that best meets those objectives. The objectives are (1) regionalization (estimate flows or flow characteristics at ungaged sites in 11 hydrologically similar regions), (2) major flow (obtain flow rates and volumes in large streams), (3) outflow from the State (account for streamflow leaving the State), and (4) streamflow conditions assessment (assess current conditions with regard to long-term data, and define temporal trends in flow). The network analysis resulted in a proposed core network of 263 stations. Of those 263 stations, 43 were discontinued as of October 1, 1999, and 15 were partial-record stations. Fifty-five of the proposed core-network stations meet two of the four major objectives, 16 stations meet three objectives, and 1 station meets all four. One-hundred eighty-five stations with a median record length of 33 years were selected to meet the regionalization objective. Ninety-two stations with a median record length of about 62 years were selected to meet the major-flow objective. Twenty-six stations with a median record length of 59 years were selected to meet the outflow from the State objective. Fifty stations with a median record length of 53 years were selected to meet the streamflow conditions assessment objective.

Texas↗
USGS2002

Changes in ground-water quality in the Canal Creek Aquifer between 1995 and 2000-2001, West Branch Canal Creek area, Aberdeen Proving Ground, Maryland

Since 1917, Aberdeen Proving Ground, Maryland has been the primary chemical-warfare research and development center for the U.S. Army. Ground-water contamination has been documented in the Canal Creek aquifer because of past disposal of chemical and ordnance manufacturing waste. Comprehensive sampling for volatile organic compounds in ground water by the U.S. Geological Survey in the West Branch Canal Creek area was done in June?October 1995 and June?August 2000. The purpose of this report is (1) to compare volatile organic compound concentrations and determine changes in the ground-water contaminant plumes along two cross sections between 1995 and 2000, and (2) to incorporate data from new piezometers sampled in spring 2001 into the plume descriptions. Along the southern cross section, total concentrations of volatile organic compounds in 1995 were determined to be highest in the landfill area east of the wetland (5,200 micrograms per liter), and concentrations were next highest deep in the aquifer near the center of the wetland (3,300 micrograms per liter at 35 feet below land surface). When new piezometers were sampled in 2001, higher carbon tetrachloride and chloroform concentrations (2,000 and 2,900 micrograms per liter) were detected deep in the aquifer 38 feet below land surface, west of the 1995 sampling. A deep area in the aquifer close to the eastern edge of the wetland and a shallow area just east of the creek channel showed declines in total volatile organic compound concentrations of more than 25 percent, whereas between those two areas, con-centrations generally showed an increase of greater than 25 percent between 1995 and 2000. Along the northern cross section, total concentrations of volatile organic compounds in ground water in both 1995 and 2000 were determined to be highest (greater than 2,000 micrograms per liter) in piezometers located on the east side of the section, farthest from the creek channel, and concentrations were progressively lower at piezometer locations closer to the creek channel. Total volatile organic compound concentrations increased more than 25 percent in some areas in the middle depths of the aquifer; however, it could not be determined if a defined plume was moving farther downgradient along ground-water flow paths toward the creek channel, or vertically downward because of density differences within the aquifer.

Water-Resources Investigations Report↗
USGS1978

Interpretation of well logs in a carbonate aquifer

This report describes the log analysis of the Randolph and Sabial core holes in the Edwards aquifer in Texas, with particular attention to the principles that can be applied generally to any carbonate system. The geologic and hydrologic data were obtained during the drilling of the two holes, from extensive laboratory analysis of the cores, and from numerous geophysical logs run in the two holes. Some logging methods are inherently superiors to others for the analysis of limestone and dolomite aquifers. Three such systems are the dentistry, neutron, and acoustic-velocity (sonic) logs. Most of the log analysis described here is based on the interpretation of suites of logs from these three systems. In certain instances, deeply focused resistivity logs can be used to good advantage in carbonate rock studies; this technique is used to computer the water resistivity in the Randolph core hole. The rocks penetrated by the Randolph core hole are typical of those carbonates that have undergone very little solution by recent ground-water circulation. There are few large solutional openings; the water is saline; and the rocks are dark, dolomitic, have pore space that is interparticle or intercrystalline, and contain unoxidized organic material. The total porosity of rocks in the saline zone is higher than that of rocks in the fresh-water aquifer; however, the intrinsic permeability is much less in the saline zone because there are fewer large solutional openings. The Sabinal core hole penetrates a carbonate environment that has experienced much solution by ground water during recent geologic time. The rocks have high secondary porosities controlled by sedimentary structures within the rock; the water is fresh; and the dominant rock composition is limestone. The relative percentages of limestone and dolomite, the average matrix (grain) densities of the rock mixtures , and the porosity of the rock mass can be calculated from density, neutron, and acoustic logs. With supporting data from resistivity logs, the formation water quality can be estimated, as well as the relative cementation or tortuosity of the rock. Many of these properties calculated from logs can be verified by analysis of the core available from test holes drilled in the saline and fresh water zones.

Texas↗
USGS1974

A method for estimating magnitude and frequency of floods in South Dakota

A general flood-frequency analysis has provided a method for estimating flood magnitudes and frequencies on South Dakota streams. Related flood data useful in planning and design also are included in the report. Two distinct hydrologic regions are delineated within the State. The divisional boundary for these regions is, in general, the western divide of the James River basin. For each region, the 2-, 5-, 10-, 25-, 50-, and 100-year floods are related to basin and climatic characteristics by regression equations. Indices based on contributing drainage area size, elevation, and mean annual precipitation were found to be the most useful variables in estimation of South Dakota floods. Regional relationships based on these variables can be used to estimate floods of selected frequency at most ungaged sites where peak flows are not significantly affected by regulation or other manmade works. Equations and graphs presented are applicable to drainage basins with areas approximately from 0.1 to 4,000 square miles (0.3 to 10,400 square kilometres) in the Eastern Region and from 0.1 to 9,000 square miles (0.3 to 23,300 square kilometres) in the Western Region. Limitations on use of these equations are given and the accuracy of resulting estimates is discussed. Flood characteristics are tabulated for 130 gaging stations having 10 or more years of record. These frequency data may provide the best estimates of floods at these gaged sites. Also, maximum flood peaks determined at 188 gaging stations and 52 miscellaneous sites are compared with regional flood relationships. Individual relationships are presented for the main-stem portions of selected streams where significant regulation is a factor or where drainage areas exceed the limits of applicability of the regional relationships.

South Dakota↗
USGS1999

Estimates of ground-water discharge as determined from measurements of evapotranspiration, Ash Meadows area, Nye County, Nevada

Ash Meadows is one of the major discharge areas within the regional Death Valley ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Ash Meadows is replenished from inflow derived from an extensive recharge area that includes the eastern part of the Nevada Test Site (NTS). Currently, contaminants introduced into the subsurface by past nuclear testing at NTS are the subject of study by the U.S. Department of Energy's Environmental Restoration Program. The transport of any contaminant in contact with ground water is controlled in part by the rate and direction of ground-water flow, which itself depends on the location and quantity of ground water discharging from the flow system. To best evaluate any potential risk associated with these test-generated contaminants, studies were undertaken to accurately quantify discharge from areas downgradient from the NTS. This report presents results of a study to refine the estimate of ground-water discharge at Ash Meadows. The study estimates ground-water discharge from the Ash Meadows area through a rigorous quantification of evapotranspiration (ET). To accomplish this objective, the study identifies areas of ongoing ground-water ET, delineates unique areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions, and computes ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite images recorded in 1992 identified seven unique units representing areas of ground-water ET. The total area classified encompasses about 10,350 acres dominated primarily by lush desert vegetation. Each unique area, referred to as an ET unit, generally consists of one or more assemblages of local phreatophytes. The ET units identified range from sparse grasslands to open water. Annual ET rates are computed by energy-budget methods from micrometeorological measurements made at 10 sites within six of the seven identified ET units. Micrometeorological data were collected for a minimum of 1 year at each site during 1994 through 1997. Evapotranspiration ranged from 0.6 foot per year in a sparse, dry saltgrass environment to 8.6 feet per year over open water. Ancillary data, including water levels, were collected during this same period to gain additional insight into the evapotranspiration process. Water levels measured in shallow wells showed annual declines of more than 10 feet and daily declines as high as 0.3 foot attributed to water losses associated with evapotranspiration. Mean annual ET from the Ash Meadows area is estimated at 21,000 acre-feet. An estimate of ground-water discharge, based on this ET estimate, is presented as a range to account for uncertainties in the contribution of local precipitation. The estimates given for mean annual ground-water discharge range from 18,000 to 21,000 acre-feet. The low estimate assumes a large contribution from local precipitation in computed ET rates; whereas, the high estimate assumes no contribution from local precipitation. The range presented is only slightly higher than previous estimates of ground-water discharge from the Ash Meadows area based primarily on springflow measurements.

Nevada↗
USGS1999

Nitrate, volatile organic compounds, and pesticides in ground water — A summary of selected studies from New Jersey and Long Island, New York

This report describes the ground-water systems in the unconsolidated sand and gravel aquifers of the Coastal Plain of New Jersey and Long Island and in the fractured bedrock and valley-fill aquifers of northern New Jersey; summarizes current knowledge about the occurrence and distribution of nitrate, volatile organic compounds (VOCs), and pesticides in these systems; and explains why some ground-water systems are more vulnerable to comtamination than others. Although the vulnerability of ground water to contamination from the land surface is influenced by many factors, the degree of aquifer confinement, the depth of the well, and the surrounding land use are key factors. Unconfined aquifers generally are much more vulnerable to contamination than confined aquifers. For a well in a confined aquifer, the farther the well is from the unconfined area, the less vulnerable it is to contamination. Generally, the deeper the well, the less vulnerable it is to contamination. Finally, because human activities greatly affect the quality of water that recharges an aquifer, the amount and type of land use in the area that contributes water to the well is a key factor in determining vulnerability. Nitrate contamination of ground water typically occurs in agricultural and residential areas, especially where the aquifer is very permeable and unconfined and nitrogen-fertilizer use is high. In New Jersey and on Long Island, concentrations of nitrate exceed the U.S. Environmental Protection Agency Maximum Contaminant Level (MCL) more often than those of VOCs or pesticides. Nitrate contamination generally is associated with nonpoint sources. VOC contamination of ground water occurs primarily in urban areas, especially in mixed urban and industrial areas where chemicals are used. In general, VOC concentrations are low and do not exceed MCLs. High concentrations of VOCs generally are associated with point sources. Pesticide contamination of ground water occurs in some agricultural and residential areas, where the aquifer is very permeable and unconfined, and where the chemicals are used. Concentrations of pesticides in New Jersey and on Long Island generally are low; in agricultural areas of Long Island, however, some have been found to exceed MCLs. Pesticide contamination generally is associated with nonpoint sources.

New Jersey, New York↗
USGS2003

Hydrogeology of a Biosolids-Application Site Near Deer Trail, Colorado, 1993-99

This report presents hydrogeology data and interpretations resulting from two studies related to biosolids applications at the Metro Wastewater Reclamation District property near Deer Trail, Colorado, done by the U.S. Geological Survey in cooperation with the Metro Wastewater Reclamation District: (1) a 1993-99 study of hydrology and water quality for the Metro Wastewater Reclamation District central property and (2) a 1999 study of regional bedrock-aquifer structure and local ground-water recharge. Biosolids were applied as a fertilizer during late 1993 through 1999. The 1993 Metro Wastewater Reclamation District property boundary constitutes the study area, but hydrogeologic structure maps for a much larger area are included in the report. The study area is located on the eastern margin of the Denver Basin, a bowl-shaped sequence of sedimentary rocks. The uppermost bedrock formations in the vicinity of the study area consist of the Pierre Shale, the Fox Hills Sandstone, and the Laramie Formation, parts of which comprise the Laramie-Fox Hills hydrostratigraphic unit and thus, where saturated, the Laramie-Fox Hills aquifer. In the vicinity of the study area, the Laramie-Fox Hills hydrostratigraphic unit dips gently to the northwest, crops out, and is partially eroded. The Laramie-Fox Hills aquifer is either absent or not fully saturated within the Metro Wastewater Reclamation District properties, although this aquifer is the principal aquifer used for domestic supply in the vicinity of the study area. Yield was small from two deep monitoring wells in the Laramie-Fox Hills aquifer within the study area. Depth to water in these wells was about 110 and 150 feet below land surface, and monthly water levels fluctuated 0.5 foot or less. Alluvial aquifers also are present in the unconsolidated sand and loess deposits in the valleys of the study area. Interactions of the deeper parts of the Laramie-Fox Hills aquifer with shallow ground water in the study area include a general close hydraulic connection between alluvial and bedrock aquifers, recharge of the Cottonwood Creek and much of the Muddy Creek alluvial aquifers by the bedrock aquifer, and possible recharge of the bedrock aquifer by a Rattlesnake Creek tributary. Some areas of shallow ground water were recharged by infiltration from rain or ponds, but other areas likely were recharged by other ground water. Data for shallow ground water indicate that ground-water recharge takes less than a day at some sites to about 40 years at another site. Depth to shallow ground water in the study area ranged from about 2 feet to about 37 feet below land surface. Shallow ground-water levels likely were affected by evapotranspiration. Ground water is present in shallow parts of the bedrock aquifer or in alluvial aquifers in four drainage basins: Badger Creek, Cottonwood Creek, Muddy Creek, and Rattlesnake Creek. These drainage basins generally contained only ephemeral streams, which flow only after intense rain.

Water-Resources Investigations Report↗
USGS1984

Cost-effectiveness of the stream-gaging program in Iowa

This report documents the results of a study of the cost-effectiveness of the stream-gaging program in Iowa. Data uses and funding sources were identified for the 122 surface-water stations (including reservoir, lake, stage only, and miscellaneous stations) operated by the U. S. Geological Survey in Iowa. There are 110 continuous streamflow stations currently being operated in Iowa with an annual budget of $592,000. The average standard error of estimation in continuous streamflow records is 11.4 percent. It was shown that this overall degree of accuracy at the 110 continuous streamflow stations could be improved to 10.5 percent if the gaging schedule was optimized. A minimum budget of $543,000 is required to operate the present streamgaging program in Iowa. With this budget, routine visits to gages would be decreased to five during the open-water season and three during the winter. A budget less than this does not permit proper maintenance of the gages and recorders. At the minimum budget, the average standard error would be 12.5 percent. The maximum budget analyzed was $1,235,000, which resulted in an average standard error of 4.2 percent. A 10 percent increase in the current budget to $656,000 would result in a standard error of 8.4 percent. There are still a few basins with drainage areas greater than 200 square miles that have no continuous streamflow data. Continuous streamflow gages need to be established in these basins as funds become available. All stations in the current program need to be maintained for the forseeable future. Data simulated by using the flow-routing and regression methods for stations in 6 river basins do not meet the accuracy required for their data use. Other basins will be studied later to determine if alternative methods to meet accuracy standards are feasible.

Iowa↗