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At least 721 records · Page 40Linked to original sources
USGS2000

Relation of bacteria in limestone aquifers to septic systems in Berkeley County, West Virginia

Water samples collected from 50 wells in Berkeley County, West Virginia, during June 2000 were analyzed for indicator bacteria. Of the 50 wells sampled, 62 percent (31 wells) contained total coliform bacteria , 32 percent (16 wells) contained Escherichia coli, and 30 percent (15 wells) contained fecal coliform bacteria. Although bacteria were present in many wells regardless of the number of septic systems in a 5-acre circular area around each well, no apparent correlation was detected between septic-system density and concentrations of bacteria colonies. There was also little difference in the frequency of total coliform bacteria detection between shallow and deep wells; however, the highest concentrations of E. coli and fecal coliform bacteria were found in the shallowest wells. At least one of the three bacteria types was found in samples of untreated water in 32 of the 50 wells. At 21 of the 32 wells with bacteria present, there was no treatment of the ground water to remove bacteria.

West Virginia↗
USGS2001

Effects of remedial grouting on the ground-water flow system at Red Rock Dam near Pella, Iowa

Previous studies have shown direct evidence of under-seepage at Red Rock Dam on the Des Moines River near Pella, Iowa. Underseepage is thought to occur primarily on the northeast side of the dam in the lower bedrock of the St. Louis Limestone, which consists of discontinuous basal evaporite beds and an overlying cavity zone. Because of concerns about the integrity of the dam, the U.S. Army Corps of Engineers initiated a remedial grouting program in September 1991. To assess the effectiveness of the remedial grouting program and to evaluate methods for future assessments, a study was conducted by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers. Potentiometric surface maps of the overburden and bedrock indicate that the direction of ground-water flow on the northeast side of the dam has changed little from pre-grout to post-grout periods. A comparison of water levels, between a pre-grout date and a post-grout date, shows that water levels decreased but that the decrease may be more attributable to changes in dam operations than to remedial grouting. Waterlevel data for the same two dates indicate that a more gradual potentiometric surface exists on the northeast side of the dam than on the southwest side of the dam, which suggests that the hydraulic connection between Lake Red Rock and downgradient bedrock wells still is greater on the northeast side of the dam than on the southwest side. Hydrographs for some wells on the northeast side of the dam indicated a departure from pre-grout trends at approximately the same time grouting was initiated. To varying degrees, hydrographs for the same wells then appear to return to a trend similar to pre-grout years, possibly as a result of new flow paths developing over time after remedial grouting. Spearman correlation coefficients computed for water levels in wells, pool, and tailwater indicate that some areas on the northeast side of the dam appear to be less under the influence of changing pool elevations after grouting than before grouting. This suggests that the hydraulic connection between the Red Rock pool and some downgradient areas has decreased. Analysis of water samples collected from selected wells on the northeast side of the dam shows significant increases in sulfate concentrations beginning about the same time remedial grouting was done upgradient from the wells, possibly indicating that flow paths were cut off to these wells, thereby reducing the amount of mixing with fresh reservoir water. Observable changes in chloride concentrations or trends as a result of remedial grouting were not apparent. Analysis results for hydrogen and oxygen stable isotope samples collected since 1995 indicate large seasonal fluctuations of isotope ratios in the tailwater (assumed representative of the reservoir). Similar but more subdued fluctuations were observed at some wells, but other wells appeared to have little seasonal change. Stable sulfur isotope results indicate the presence of distinct water types between Lake Red Rock and in ground water from downgradient bedrock wells. Sulfur isotope values from samples from a bedrock well located upgradient from the grout curtain indicate a mixture of pool and ground water, whereas samples from downgradient overburden wells have values similar to the pool. Samples from the bedrock wells downgradient from the grout curtain have sulfur isotope values similar to a value obtained from analysis of a gypsum and anhydrite core sample. Hydrographs, statistical analysis of waterlevel data, and water-chemistry data suggest that underseepage on the northeast side of the dam has been reduced but not completely eliminated. Some areas appear to have been affected to a greater degree and for a longer period of time than other areas. Future monitoring of water levels, water chemistry, and stable isotopes can aid in the evaluation of the long-term effectiveness of remedial grouting.

Iowa↗
USGS2001

Techniques for estimating flood-frequency discharges for streams in Iowa

A statewide study was conducted to develop regression equations for estimating flood-frequency discharges for ungaged stream sites in Iowa. Thirty-eight selected basin characteristics were quantified and flood-frequency analyses were computed for 291 streamflow-gaging stations in Iowa and adjacent States. A generalized-skew-coefficient analysis was conducted to determine whether generalized skew coefficients could be improved for Iowa. Station skew coefficients were computed for 239 gaging stations in Iowa and adjacent States, and an isoline map of generalized-skew-coefficient values was developed for Iowa using variogram modeling and kriging methods. The skew map provided the lowest mean square error for the generalized-skew- coefficient analysis and was used to revise generalized skew coefficients for flood-frequency analyses for gaging stations in Iowa. Regional regression analysis, using generalized least-squares regression and data from 241 gaging stations,was used to develop equations for three hydrologic regions defined for the State. The regression equations can be used to estimate flood discharges that have recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years for ungaged stream sites in Iowa. One-variable equations were developed for each of the three regions and multi-variable equations were developed for two of the regions. Two sets of equations are presented for two of the regions because one-variable equations are considered easy for users to apply and the predictive accuracies of multi-variable equations are greater. Standard error of prediction for the one-variable equations ranges from about 34 to 45 percent and for the multi-variable equations ranges from about 31 to 42 percent. A region-of-influence regression method was also investigated for estimating flood-frequency discharges for ungaged stream sites in Iowa. A comparison of regional and region-of influence regression methods, based on ease of application and root mean square errors, determined the regional regression method to be the better estimation method for Iowa. Techniques for estimating flood-frequency discharges for streams in Iowa are presented for determining (1) regional regression estimates for ungaged sites on ungaged streams; (2) weighted estimates for gaged sites; and (3) weighted estimates for ungaged sites on gaged streams. The technique for determining regional regression estimates for ungaged sites on ungaged streams requires determining which of four possible examples applies to the location of the stream site and its basin. Illustrations for determining which example applies to an ungaged stream site and for applying both the one-variable and multi-variable regression equations are provided for the estimation techniques.

Illinois, Iowa, Minnesota, Missouri, Nebraska, Sou↗
USGS2001

Ground-water hydrology of Dugway Proving Ground and adjoining area, Tooele and Juab counties, Utah

Dugway Proving Ground (DPG) is a U.S. Department of Defense chemical, biological, and explosives testing facility in northwestern Utah. The facility includes about 620 mi 2 in Tooele County. The town of Dugway, referred to as English Village, is the administrative headquarters for the military facility, the primary residential area, and community center. The English Village area is located at the southern end of Skull Valley and is separated from the Fries area by a surface-water divide. Most of the facility is located just to the west of Skull Valley in Government Creek Valley, Dugway Valley, and the Great Salt Lake Desert (fig. 1).

Utah↗
USGS2000

Field testing of passive diffusion bag samplers for volatile organic compound concentrations in ground water, Naval Industrial Reserve Ordnance Plant, Fridley, Minnesota, November 1999 and May 2000

Volatile organic compound concentrations from passive diffusion bag samplers were compared with concentrations from conventional purge (three or more casing volumes) sampling and low-flow purge sampling in side-by-side tests in 17 wells at the Naval Industrial Reserve Ordnance Plant, in Fridley, Minnesota. An initial comparison of 1,2-dichloroethene and trichloroethene concentrations obtained by using passive diffusion bag samplers and the conventional purge method in wells where one passive diffusion bag sampler was deployed showed good agreement at several wells but poor agreement at others. Collection of data from multiple diffusion samplers during the conventional purge sampling and during the low-flow sampling, however, suggests that the volatile organic compound concentrations from the passive diffusion bag samplers accurately reflect the volatile organic compound distribution in the screened interval, whereas the conventional purge and low-flow purge samples reflect mixing during pumping. The data also show that contaminant stratification was present in some wells. In one well, trichloroethene concentrations ranged from 470 to 1,600 micrograms per liter over a vertical distance of approximately 6 feet.

Water-Resources Investigations Report↗
USGS2000

Water-quality assessment of the Sacramento River Basin, California — Water quality of fixed sites, 1996-1998

Water-quality samples were collected from 12 sites in the Sacramento River Basin, Cali-fornia, from February 1996 through April 1998. Field measurements (dissolved oxygen, pH, specific conductance, alkalinity, and water tem-perature) were completed on all samples, and laboratory analyses were done for suspended sediments, nutrients, dissolved and particulate organic carbon, major ions, trace elements, and mercury species. Samples were collected at four types of locations on the Sacramento River?large tributaries to the Sacramento River, agricul-tural drainage canals, an urban stream, and a flood control channel. The samples were collected across a range of flow conditions representative of those sites during the timeframe of the study. The water samples from the Sacramento River indi-cate that specific conductance increases slightly downstream but that the water quality is indicative of dilute water. Water temperature of the Sacramento River increases below Shasta Lake during the spring and summer irrigation season owing to diversion of water out of the river and subsequent lower flow. All 12 sites had generally low concentrations of nutrients, but chlorophyll concentrations were not measured; therefore, the actual consequences of nutrient loading could not be adequately assessed. Concentrations of dis-solved organic carbon in samples from the Sacramento River and the major tributaries were generally low; the formation of trihalomethanes probably does not currently pose a problem when water from the Sacramento River and its major tributaries is chlorinated for drinking-water purposes. However, dissolved organic carbon concentrations were higher in the urban stream and in agricultural drainage canals, but were diluted upon mixing with the Sacramento River. The only trace element that currently poses a water-quality problem in the Sacramento River is mercury. A federal criterion for the protection of aquatic life was exceeded during this study, and floodwater concentrations of mercury were mostly higher than the criterion. Exceedances of water-quality standards happened most frequently during winter when suspended-sediment concen-trations also were elevated. Most mercury is found in association with suspended sediment. The greatest loading or transport of mercury out of the Sacramento River Basin to the San Francisco Bay occurs in the winter and principally follows storm events.

California↗
USGS2000

Predevelopment water-level map of the Santa Fe Group aquifer system in the middle Rio Grande basin between Cochiti Lake and San Acacia, New Mexico

Because of its increasing population and limited water resources, the Middle Rio Grande Basin between Cochiti Lake and San Acacia, New Mexico, has recently become the subject of intense study. In particular, the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque has constructed a series of ground-water-flow models of the Tertiary and Quaternary basin-fill deposits of the Santa Fe Group aquifer system (Kernodle and Scott, 1986; Kernodle and others, 1987; Kernodle and others, 1995; Kernodle, 1998; Tiedeman and others, 1998). The ground-water-flow system also has been the focus of hydrochemical studies and other efforts intended largely to help develop an improved flow model. Among the information critical to a thorough understanding of the ground-water-flow system are water-level data that indicate the directions of ground-water flow and the magnitudes of hydraulic gradients in the aquifer prior to perturbation by substantial ground-water withdrawals (under predevelopment conditions).

Water-Resources Investigations Report↗
USGS2001

Source identification and fish exposure for polychlorinated biphenyls using congener analysis from passive water samplers in the Millers River basin, Massachusetts

Measurements of elevated concentrations of polychlorinated biphenyls (PCBs) in fish and in streambed sediments of the Millers River Basin, Massachusetts and New Hampshire, have been reported without evidence of the PCB source. In 1999, an investigation was initiated to determine the source(s) of the elevated PCB concentrations observed in fish and to establish the extent of fish exposure to PCBs along the entire main stems of the Millers River and one of its tributaries, the Otter River. Passive samplers deployed for 2-week intervals in the water-column at 3 1 stations, during summer and fall 1999, were used to assess PCB concentrations in the Millers River Basin. The samplers concentrate PCBs, which diffuse from the water column through a polyethylene membrane to hexane (0.200 liters) contained inside the samplers. Only dissolved PCBs (likely equivalent to the bioavailable fraction) are subject to diffusion through the membrane. The summed concentrations of all targeted PCB congeners (summed PCB) retrieved from the samplers ranged from 1 to 8,000 nanograms per hexane sample. Concentration and congener-pattern comparisons indicated that the historical release of PCBs in the Millers River Basin likely occurred on the Otter River at the upstream margin of Baldwinville, Mass. Elevated water-column concentrations measured in a wetland reach on the Otter River downstream from Baldwinville were compatible with a conceptual model for a present-day (1999) source in streambed sediments, to which the PCBs partitioned after their original introduction into the Otter River and from which PCBs are released to the water now that the original discharge has ceased or greatly decreased. Two four-fold decreases in summed PCB concentrations in the Millers River, by comparison with the highest concentration on the Otter River, likely were caused by (1) dilution with water from the relatively uncontaminated upstream Millers River and (2) volatilization of PCBs from the Millers River in steep-gradient reaches. A relatively constant concentration of summed PCBs in the reach of the Millers River from river mile 20 to river mile 10 was likely a consequence of a balance between decreased volatilization rates in that relatively low-gradient reach and resupply of PCBs to the water column from contaminated streambed sediments. A second high-gradient reach from river mile 10 to the confluence of the Millers River with the Connecticut River also was associated with a decrease in concentration of water-column summed PCBs. Volatilization as a loss mechanism was supported by evidence in the form of slight changes of the congener pattern in the reaches where decreases occurred. Exposure of fish food webs to concentrations of dissolved PCBs exceeded the U.S. Environmental Protection Agency's water-quality criterion for PCBs throughout most of the Millers River and Otter River main stems. Because the apparent source of PCBs discharged was upstream on the Otter River, a large number of river miles downstream (more than 30 mi) had summer water-column PCB concentrations that would likely lead to high concentrations of PCBs in fish.

Water-Resources Investigations Report↗
USGS2001

Simulation of ground-water discharge to Biscayne Bay, southeastern Florida

As part of the Place-Based Studies Program, the U.S. Geological Survey initiated a project in 1996, in cooperation with the U.S. Army Corps of Engineers, to quantify the rates and patterns of submarine ground-water discharge to Biscayne Bay. Project objectives were achieved through field investigations at three sites (Coconut Grove, Deering Estate, and Mowry Canal) along the coastline of Biscayne Bay and through the development and calibration of variable-density, ground-water flow models. Two-dimensional, vertical cross-sectional models were developed for steady-state conditions for the Coconut Grove and Deering Estate transects to quantify local-scale ground-water discharge patterns to Biscayne Bay. A larger regional-scale model was developed in three dimensions to simulate submarine ground-water discharge to the entire bay. The SEAWAT code, which is a combined version of MODFLOW and MT3D, was used to simulate the complex variable-density flow patterns. Field data suggest that ground-water discharge to Biscayne Bay relative to the shoreline is restricted to within 300 meters at Coconut Grove, 600 to 1,000 meters at Deering Estate, and 100 meters at Mowry Canal. The vertical cross-sectional models, which were calibrated to the field data using the assumption of steady state, tend to focus ground-water discharge to within 50 to 200 meters of the shoreline. With homogeneous distributions for aquifer parameters and a constant-concentration boundary for Biscayne Bay, the numerical models could not reproduce the lower ground-water salinities observed beneath the bay, which suggests that further research may be necessary to improve the accuracy of the numerical simulations. Results from the cross-sectional models, which were able to simulate the approximate position of the saltwater interface, suggest that longitudinal dispersivity ranges between 1 and 10 meters, and transverse dispersivity ranges from 0.1 to 1 meter for the Biscayne aquifer. The three-dimensional, regional-scale model was calibrated to ground-water heads, canal baseflow, and the general position of the saltwater interface for nearly a 10-year period from 1989 to 1998. The mean absolute error between observed and simulated head values is 0.15 meter. The mean absolute error between observed and simulated baseflow is 3 x 105 cubic meters per day. The position of the simulated saltwater interface generally matches the position observed in the field, except for areas north of the Miami Canal where the simulated saltwater interface is located about 5 kilometers inland of the observed saltwater interface. Results from the regional-scale model suggest that the average rate of fresh ground-water discharge to Biscayne Bay for the 10-year period (1989-98) is about 2 x 105 cubic meters per day for 100 kilometers of coastline. This simulated discharge rate is about 6 percent of the measured surface-water discharge to Biscayne Bay for the same period. The model also suggests that nearly 100 percent of the fresh ground-water discharge is to the northern half of Biscayne Bay, north of the Cutler Drain Canal. South of the Cutler Drain Canal, coastal lowlands prevent the water table from rising high enough to drive measurable quantities of ground water to Biscayne Bay. Annual variations in sea-level elevation, which can be as large as 0.3 meter, have a substantial effect on rates of ground-water discharge. During 1989-98, simulated rates of ground-water discharge to Biscayne Bay generally are highest when sea level is relatively low.

Florida↗
USGS2000

Use of air-pressurized slug tests to estimate hydraulic conductivity at selected piezometers completed in the Santa Fe Group aquifer system, Albuquerque area, New Mexico

The City of Albuquerque Public Works Department, Water Resources Management (City), is interested in quantifying aquifer hydraulic properties in the Albuquerque, New Mexico, area to better understand and manage water resources in the Middle Rio Grande Basin. In 1998, the City and the U.S. Geological Survey entered into a cooperative program to determine hydraulic properties of aquifer material adjacent to screened intervals of piezometers in the Albuquerque area. Investigators conducted slug tests from March 8 through April 8, 1999, to estimate hydraulic conductivity of aquifer material adjacent to the screened intervals of 25 piezometers from 11 nested- piezometer sites in the Albuquerque area. At 20 of the piezometers, slug-test responses were typical; at 2 piezometers, tests were prematurely terminated because the tests were taking too long to complete; and at 3 piezometers, test responses were oscillatory. Methods used to estimate hydraulic conductivity were the Bouwer and Rice method or the Cooper, Bredehoeft, and Papadopulos method for most tests; the Shapiro and Greene method for prematurely terminated tests; and the van der Kamp method for oscillatory tests. Hydraulic-conductivity estimates ranged from about 0.15 to 92 feet per day. In general, the smaller estimated values are associated with fine-grained aquifer materials and the larger estimated hydraulic-conductivity values are associated with coarse- grained aquifer materials adjacent to the screened intervals of the piezometers. Hydraulic-conductivity estimates ranged from 0.15 to 8.2 feet per day for aquifer materials adjacent to the screened intervals at 12 piezometers and from 12 to 41 feet per day for aquifer materials adjacent to the screened intervals at 10 piezometers. Hydraulic-conductivity estimates at four piezometers were greater than 41 feet per day.

Water-Resources Investigations Report↗
USGS2001

Historical water-quality data for the High Plains Regional Ground-Water Study Area in Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming, 1930-98

The High Plains aquifer underlies 174,000 square miles in parts of eight States and includes eight primary hydrogeologic units, including the well-known Ogallala Formation. The High Plains aquifer is an important resource, providing water for 27 percent of the Nation?s irrigated agricultural lands in an otherwise dry landscape. Since the 1980?s there has been concern over the sustainability of the aquifer due to water-level declines caused by substantial pumping. Water quality of the aquifer is a more recent concern. As part of the U.S. Geological Survey?s National Water-Quality Assessment Program, historical water-quality data have been gathered for the High Plains Regional Ground-Water Study Area into a retrospective data base, which can be used to evaluate the occurrence and distribution of water-quality constituents of concern.Data from the retrospective data base verify that nitrate, pesticides, and dissolved solids (salinity) are important water-quality concerns in the High Plains study area. Sixteen percent of all measured nitrate concentrations were larger than the U.S. Environmental Protection Agency drinking-water standard of 10 milligrams per liter. In about 70 percent of the counties within the High Plains study area, nitrate concentrations for 1980-98 were significantly larger than for 1930-69. While nitrate concentrations are largest where depth to water is shallow, concentrations also have increased in the Ogallala Formation where depth to water is large. Pesticide data primarily are available only in the northern half of the study area. About 50 pesticides were detected in the High Plains study area, but only four pesticides (atrazine, alachlor, cyanazine, and simazine) had concentrations exceeding a drinking-water standard. The occasional detection of pesticides in deeper parts of the Ogallala Formation indicates that contamination pathways exist. Dissolved solids, which are a direct measure of salinity, had 29 percent of measured concentrations in excess of the secondary drinking-water standard of 500 milligrams per liter. Comparison of dissolved-solids concentrations prior to 1980 to concentrations after 1980 indicates dissolved-solids concentrations have increased in the alluvial valleys of the Platte, the Republican, and the Arkansas Rivers, as well as in the Ogallala Formation?South hydrogeologic unit.Water-quality results indicate that human activities are affecting the water of the High Plains aquifer. Because there is a potential for water quality to become impaired relative to the historical uses of the aquifer, water quality needs to be considered when evaluating the sustainability of the High Plains aquifer. Data collected as part of the High Plains Regional Ground-Water Study will help to fill in gaps in water-quality information and provide additional information for understanding the factors that govern ambient water quality.

Colorado, Kansas, Nebraska, New Mexico, Oklahoma, ↗
USGS2001

Comparison of U.S. Geological Survey and Ohio Environmental Protection Agency fish-collection methods using the index of biotic integrity and modified index of well-being, 1996–97

The U.S. Geological Survey (USGS) and Ohio Environmental Protection Agency (OEPA) collected data on fish from 10 stream sites in 1996 and 3 stream sites in 1997 as part of a comparative study of fish community assessment methods. The sites sampled represent a wide range of basin sizes (ranging from 132–6,330 square kilometers) and surrounding land-use types (urban, agricultural, and mixed). Each agency used its own fish-sampling protocol. Using the Index of Biotic Integrity and Modified Index of Well-Being, differences between data sets were tested for significance by means of the Wilcoxon signed-ranks test ( α = 0.05). Results showed that the median of Index of Biotic Integrity differences between data sets was not significantly different from zero ( p = 0.2521); however, the same statistical test showed the median differences in the Modified Index of Well-Being scores to be significantly different from zero ( p = 0.0158). The differences observed in the Index of Biotic Integrity scores are likely due to natural variability, increased variability at sites with degraded water quality, differences in sampling methods, and low-end adjustments in the Index of Biotic Integrity calculation when fewer than 50 fish were collected. The Modified Index ofWell-Being scores calculated by OEPA were significantly higher than those calculated by the USGS. This finding was attributed to the comparatively large numbers and biomass of fish collected by the OEPA. By combining the two indices and viewing them in terms of the percentage attainment of Ohio Warmwater Habitat criteria, the two agencies’ data seemed comparable, although the Index of Biotic Integrity scores were more similar than the Modified Index of Well-Being scores.

Michigan, New York, Ohio, Pennsylvania↗
USGS2000

Stream discharge measurements under ice cover

This training presentation shows procedures used by the U.S. Geological Survey to measure streamflow when streams are covered by ice. Although 'Ice Measurements' are generally more difficult to make than open-water measurements and are often made under uncomfortable conditions it is very important that ice measurements be made regularly during the winter. This is because a large part of many winter discharge records depend on such measurements.

Water-Resources Investigations Report↗