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At least 1,765 records · Page 98Linked to original sources

USGS1999

Water resources data, Ohio, water year 1998, volume 2. St. Lawrence River Basin and statewide project data

Water-resources data for the 1998 water year for Ohio consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground-water wells. This report, in two volumes, contains records for water discharge at 127 gaging stations and 65 partial-record sites; water levels at 348 observation wells and 24 crest-stage gages; and water quality at 25 gaging stations, 317 observation wells, and 26 partial-record sites. Also included are data from miscellaneous and synoptic sites. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements and analyses. These data represent that part of the National Water Information System collected by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Ohio.

Water Data Report↗

USGS2000

Water resources data, Ohio, water year 1999, Volume 1. Ohio River Basin excluding project data

Water-resources data for the 1999 water year for Ohio consist of records of stage, discharge, and water quality of streams; stage and contents of lakes and reservoirs; and water levels and water quality of ground-water wells. This report, in two volumes, contains records for water discharge at 120 gaging stations and 69 partial-record sites; water levels at 187 observation wells and 26 crest-stage gages; and water quality at 34 gaging stations, 337 observation wells, and 3 partial-record sites. Also included are data from miscellaneous and synoptic sites. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurements and analyses. These data represent that part of the National Water Information System collected by the U.S. Geological Survey and cooperating Federal, State, and local agencies in Ohio.

Ohio↗

USGS2001

Water resources data, Ohio, water year 1999, volume 2. St. Lawrence River Basin and statewide project data

Ohio↗

USGS2005

Water resources data, Wyoming, water year 2004; Volume 1. Surface water; with List of discontinued and active surface-water, water-quality, sediment, and biological stations

Water resources data for the 2004 water year for Wyoming consist of records of stage, discharge and water quality of streams; stage and contents of lakes and reservoirs, and water levels and water quality of ground water. Volume 1 of this report contains discharge records for 164 gaging stations; water quality for 43 gaging stations and 45 ungaged stations, and stage and contents for one reservoir. Volume 2 of this report contains water levels records for 64 wells. Additional water data were collected at various sites, not part of the systematic data collection program, and are published as miscellaneous measurements. These data represent part of the National Water Information System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Wyoming.

Water Data Report↗

USGS2005

Water resources data, Wyoming, water year 2004; Volume 2. Ground water

Water Data Report↗

USGS2000

Sensitivity of ground water to contamination in Lawrence County, South Dakota

Ground-water supplies in Lawrence County, South Dakota, can be contaminated by agricultural, urban, suburban, commercial, and industrial land uses. To address this issue, the U.S. Geological Survey in cooperation with Lawrence County and the City of Spearfish mapped the sensitivity of ground water to contamination in Lawrence County. Sensitivity of ground water to contamination was determined by delineating hydrogeologic settings with common hydrogeologic characteristics as described in the DRASTIC method, developed by the U.S. Environmental Protection Agency and the National Water Well Association. Within the framework of 11 hydrogeologic settings, sensitivity to contamination was ranked for six intrinsic hydrogeologic characteristics: (1) aquifer media, (2) unsaturated media (3) hydraulic conductivity, (4) recharge rate, (5) depth to water, and (6) land-surface slope. The rating conventions of DRASTIC were modified to provide a relative ranking of hydrogeologic characteristics without assignment of a combined numerical score. Soil characteristics were not included as a map layer because detailed digital data were not available; however, the general distribution of two soil characteristics were shown. A total of 956 polygons were delineated and assigned a sensitivity-unit code that represented unique groups of sensitivity rank for the six intrinsic hydrogeologic characteristics. The polygons were created by overlaying and intersecting maps that describe the geology, precipitation, land-surface elevation, and depth to water using a geographic information system. Thirty drainage areas upstream from potential streamflow-loss zones were delineated to describe an additional mechanism of transport of potential contamination. The sensitivity of ground water to contamination was presented on a 1:100,000-scale map with code and label explanations. Limitations of the sensitivity map are described to facilitate appropriate use of the map as a screening tool to compare sensitivity to contamination.

Water-Resources Investigations Report↗

USGS2001

Hydrologic data and a proposed water-quality monitoring network for the Kobuk River basin, Gates of the Arctic National Park and Preserve, and Kobuk Valley National Park, Alaska

Located in northwestern Alaska, the Kobuk River drains a watershed of approximately 12,300 square miles. Two national parks are located in the basin: the entire Kobuk Valley National Park and and a portion of Gates of the Arctic National Park and Preserve. Reconnaissance-type water-quality data collected on the Kobuk River and some of its tributaries indicate that the water is of a calcium to calcium-magnesium-bicarbonate type. To design a representative water-quality monitoring network, a geographical information system (GIS) of the Kobuk River Basin was created. The GIS was used with a statistical technique, cluster analysis, to stratify the Kobuk River Basin into different regions. Potential water-quality monitoring sites were then selected from these regions.

Alaska↗

USGS2001

Susceptibility index to surface contamination for the Little Cross Creek watershed, Cumberland County, North Carolina

An index of surface-water contamination potential was constructed for the Little Cross Creek Basin, a 9.7-square-mile, water-supply watershed in Cumberland County, North Carolina. The index was developed because previous water-quality investigations raised concerns regarding inputs of bacteria, suspended sediment, and phosphorus from nonpoint sources in the watershed. A geographic information system was used to build map overlays and to categorize and rate three factors that affect the transport of water and contaminants-land-surface slope, distance to water, and land use/land cover. Each factor was weighted to reflect its potential contribution to surface-water contamination; the factors then were combined to estimate susceptibility values for the entire watershed. The numerical susceptibility values were categorized to indicate lowest to highest potential for surface-water contamination, and a map was produced showing the spatial distribution of these categories within the watershed. The susceptibility index for about 17 percent of the Little Cross Creek watershed is rated in the high or highest category. These areas have high slopes, short distances to the nearest surface water, impervious land cover, and land uses that generate contaminants. About 38 percent of the watershed area is rated as having low or lowest susceptibility to contamination. These areas contain flat terrain, greater distances to water, land cover that promotes infiltration, and land uses that pose little risk for generating contaminants. Approximately 43 percent of the watershed is in the moderate category of susceptibility. Open water, which is not rated, accounts for the remaining area. The susceptibility index provides water-resource managers with a tool that can aid in prioritizing areas within the Little Cross Creek Basin for monitoring, protection, and remediation. Previous suspended sediment, total phosphorus, and fecal coliform data collected in the Little Cross Creek watershed support the results of the susceptibility analysis. Although this susceptibility index is specific to the Little Cross Creek Basin, the methods used to develop the index are transferable to other watersheds.

North Carolina↗

USGS2001

Estimating the magnitude and frequency of floods in rural basins of North Carolina— Revised

A statewide study was conducted to develop two methods for estimating the magnitude and frequency of floods in rural ungaged basins in North Carolina. Flood-frequency estimates for gaged sites in North Carolina were computed by fitting the annual peak flows for each site to a log-Pearson Type III distribution. As part of the computation of flood-frequency estimates for gaged sites, new values for generalized skew coefficients were developed. Basin characteristics for these gaged sites were computed by using a geographic information system and automated computer algorithms. Flood-frequency estimates and basin characteristics for 317 gaged sites were combined to form the data base that was used for this analysis. Regional regression analysis, using generalized least-squares regression, was used to develop a set of predictive equations that can be used to estimate the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year recurrence interval discharges for rural ungaged basins in the Blue Ridge-Piedmont, Coastal Plain, and Sand Hills hydrologic areas. The predictive equations are all functions of drainage area. Average errors of prediction for these regression equations range from 36 to 65 percent. A region-of-influence method also was developed that interactively estimates recurrence interval discharges for rural ungaged basins in the Blue Ridge-Piedmont and Coastal Plain hydrologic areas of North Carolina. Regression techniques are used to develop a unique relation between flood discharge and basin characteristics for a subset of gaged sites with similar basin characteristics. This, then, can be used to estimate flood discharges at ungaged sites. Because the computations required for this method are somewhat complex, a computer application was developed that performs the computations and compares the predictive errors for this method. The computer application also includes the option of using the regression equations to compute estimated flood discharges and errors of prediction specific to each ungaged site. Root mean square errors, computed for each recurrence interval and hydrologic area, are generally only slightly lower for the region-of-influence method than for the regression equations and do not provide sufficient basis for recommending one method over the other. In addition, the region-of-influence method is a new method that is still being improved. As a result, the regional regression equations are considered to be the primary method for computing flood-frequency estimates at ungaged sites.

North Carolina↗

USGS2002

Analysis of the magnitude and frequency of the 4-day annual low flow and regression equations for estimating the 4-day, 3-year low-flow frequency at ungaged sites on unregulated streams in New Mexico

Two regression equations were developed for estimating the 4-day, 3-year (4Q3) low-flow frequency at ungaged sites on unregulated streams in New Mexico. The first, a statewide equation for estimating the 4Q3 low-flow frequency from drainage area and average basin mean winter precipitation, was developed from the data for 50 streamflow-gaging stations that had non-zero 4Q3 low-flow frequency. The 4Q3 low-flow frequency for the 50 gaging stations ranged from 0.08 to 18.7 cubic feet per second. For this statewide equation, the average standard error of estimate was 126 percent and the coefficient of determination was 0.48. The second, an equation for estimating the 4Q3 low-flowfrequency in mountainous regions from drainage area, average basin mean winter precipitation, and average basin slope, was developed from the data for 40 gaging stations located above 7,500 feet in elevation. For this regression equation, the average standard error of estimate was 94 percent and the coefficient of determination was 0.66. A U.S. Geological Survey computer-program interface for a geographical information system (GIS), called the GISWeasel,was used to determine basin and climatic characteristics for 84 gaging stations that were not affected by regulation. Mean monthly precipitation estimates from 1961 to 1990 were used in the GIS Weasel to compute the climatic characteristics of average basin winter precipitation and annual mean precipitation. The U.S. Geological Survey National Elevation Dataset, which currently consists of the 7.5-minute, 30-meter digital elevation model for each State, was used in the GISWeasel to compute the basin characteristics of drainage area, average basin slope, average basin elevation, and average basin aspect. Basin and climatic characteristics that were statistically significant in the regression equation with the 4Q3 lowflow frequency were drainage area, which ranged from 1.62 to 5,900 square miles; average basin mean winter precipitation, which ranged from 3.89 to 19.42 inches; and average basin slope, which ranged from 0.166 to 0.517 percent.

Water-Resources Investigations Report↗

USGS2002

Flood-hazard mapping in Honduras in response to Hurricane Mitch

The devastation in Honduras due to flooding from Hurricane Mitch in 1998 prompted the U.S. Agency for International Development, through the U.S. Geological Survey, to develop a country-wide systematic approach of flood-hazard mapping and a demonstration of the method at selected sites as part of a reconstruction effort. The design discharge chosen for flood-hazard mapping was the flood with an average return interval of 50 years, and this selection was based on discussions with the U.S. Agency for International Development and the Honduran Public Works and Transportation Ministry. A regression equation for estimating the 50-year flood discharge using drainage area and annual precipitation as the explanatory variables was developed, based on data from 34 long-term gaging sites. This equation, which has a standard error of prediction of 71.3 percent, was used in a geographic information system to estimate the 50-year flood discharge at any location for any river in the country. The flood-hazard mapping method was demonstrated at 15 selected municipalities. High-resolution digital-elevation models of the floodplain were obtained using an airborne laser-terrain mapping system. Field verification of the digital elevation models showed that the digital-elevation models had mean absolute errors ranging from -0.57 to 0.14 meter in the vertical dimension. From these models, water-surface elevation cross sections were obtained and used in a numerical, one-dimensional, steady-flow stepbackwater model to estimate water-surface profiles corresponding to the 50-year flood discharge. From these water-surface profiles, maps of area and depth of inundation were created at the 13 of the 15 selected municipalities. At La Lima only, the area and depth of inundation of the channel capacity in the city was mapped. At Santa Rose de Aguan, no numerical model was created. The 50-year flood and the maps of area and depth of inundation are based on the estimated 50-year storm tide.

Water-Resources Investigations Report↗

USGS2002

Water-quality data analysis of the upper Gunnison River watershed, Colorado, 1989-99

Water-quality data from October 1969 to December 1999 for both surface water and ground water in the upper Gunnison River watershed were retrieved and compiled from the U.S. Geological Survey National Water Information System and the U.S. Environmental Protection Agency Storage and Retrieval databases. Analyses focused primarily on a subset of these data from October 1989 to December 1999. The upper Gunnison River watershed is located west of the Continental Divide in the Southern Rocky Mountains physiographic province. Surface-water-quality data were compiled for 482 sites in the upper Gunnison River watershed. Most values of surface-water temperature, dissolved oxygen, and pH were within Colorado Department of Public Health and Environment (CDPHE) in-stream standards. Calcium bicarbonate type water was the most spatially dominant water type in the basin. Nutrients were most commonly sampled along the Slate River and East River near Crested Butte and along the Gunnison River from the confluence of the East and Taylor Rivers to the western edge of the watershed. Median ammonia concentrations were low, with many concentrations less than laboratory reporting levels. All nitrate concentrations met the CDPHE in-stream standard of 10 milligrams per liter. More than 30 percent of stream sites with total phosphorus data (23 of 61 sites) had concentrations greater than the U.S. Environmental Protection Agency (USEPA) recommendation for controlling eutrophication. Ammonia concentrations at a site on the Slate River near Crested Butte had a statistically significant upward trend for the 1995–99 period. The Slate River near Crested Butte site is located immediately downstream from the towns of Crested Butte and Mount Crested Butte and may reflect recent population growth or other land-use changes. However, the rate of change of the trend is small (0.017 milligram per liter per year). Although a multiple comparison test showed nitrate concentrations were statistically different between agriculture and forest sites and between agriculture and urban land-use classified sites, median concentrations were low among all land-use settings. Median concentrations of total phosphorus were greatest in rangeland areas and least in urban areas. No significant differences were identified for median concentrations of total phosphorus in agriculture and forest land-use areas. Median concentrations of arsenic, lead, mercury, selenium, and silver were low or below reporting levels throughout the watershed. Aluminum, cadmium, copper, lead, manganese, and zinc concentrations were elevated near the town of Crested Butte and on Henson Creek upstream from Lake City, which may be explained by upstream areas of historical mining. Samples for six trace elements exceeded standards: cadmium, copper, lead, manganese, silver, and zinc. A downward trend (3 micrograms per liter per year) was identified for the dissolved iron concentration at a site on the Gunnison River at County Road 32 downstream from the city of Gunnison. Streambed-sediment samples from areas affected by historical mining also had elevated concentrations of some trace elements. Chlorophyll- a concentrations in samples from Blue Mesa Reservoir and streams in the Crested Butte and Gunnison areas were typical of unenriched to moderately enriched conditions. Median concentrations of 5-day biochemical oxygen demand concentrations for sites between Crested Butte and Blue Mesa Reservoir were less than 2 milligrams per liter. Occasional high (greater than 200 counts per 100 milliliters) concentrations for fecal coliform were determined at selected sites within the study area. However, median concentrations were less than 100 counts per 100 milliliters except for the Squaw Creek and Cimarron River areas in the western part of the watershed. Ground-water-quality data have been collected by the U.S. Geological Survey from 99 wells. Many wells were completed in aquifers composed of Holocene-age valley fill and alluvium. Most field properties were within the USEPA Secondary Drinking Water Regulations (SDWR) range for treated drinking water, except for 2 (of 40) pH samples. Calcium bicarbonate was the predominant water type in nearly all aquifers except for the aquifers composed of volcanic rock, which had more sodium and sulfate mixed water types. Wells with sulfate concentrations exceeding the SDWR of 250 milligrams per liter were completed in aquifers composed of volcanic rock near Lake City. Dissolution and oxidation of sulfide minerals in these aquifers may explain the elevated sulfate concentrations in ground water at these locations. Nutrient concentrations in ground water were generally low, and median concentrations for ammonia, nitrite, and dissolved phosphorus were below reporting levels. All nitrate concentrations in the samples were below the USEPA drinking-water maximum contaminant level of 10 mg/L. No statistical difference was found in nitrate concentrations among the four land-use classifications (agriculture, forest, rangeland, and urban). Trace elements in ground water were generally below the USEPA SDWR. Three iron samples exceeded the USEPA SDWR of 300 micrograms per liter at two wells located near the city of Gunnison and at a well south of the town of Powderhorn near the Cebolla River. Nine of 39 manganese samples exceeded the USEPA SDWR of 50 micrograms per liter and were collected from aquifers composed of Holocene-age valley fill and alluvium near Gunnison and Crested Butte and in one well near the Cebolla River. Radon gas is a natural radioactive decay product of uranium. All 39 radon samples collected from ground water in the watershed exceeded the proposed USEPA drinking-water maximum contaminant level of 300 picocuries per liter and ranged from 426 to 3,830 picocuries per liter.

Colorado↗

USGS2002

Simulation of streamflow and wetland storage, Starkweather Coulee subbasin, North Dakota, water years 1981-98

A study was conducted to simulate streamflow and wetland storage within a part of the Starkweather Coulee subbasin. Information on streamflow and wetland storage in Starkweather Coulee subbasin may help with the management of water issues in the Devils Lake Basin. Information from a digital elevation model and geographic-information-system analyses of the study area was used to develop the Devils Lake Basin wetlands model. Digital elevation model data and other climatic and topographic data were used as inputs to the model. Within the study area, the average wetland depth was about 2.21 feet, the total maximum wetland area was about 30,890 acres at the overflow elevation, and the total maximum wetland volume was about 68,270 acre-feet. Model runs were made for water years 1981-98 to calibrate the model to observed streamflows that were obtained from the Starkweather Coulee gaging station. Observed annual peak streamflows were greater than simulated annual peak streamflows for all water years except 1983. The differences probably were caused mostly by the lack of a subroutine in the model to account for frozen soil. The largest amount of simulated daily wetlands area occurred in April 1997 when about 40,500 acres of the study area was covered with water. Also during April 1997, the simulated daily water volume in the open and closed wetlands combined attained a maximum of about 116,000 acre-feet. By increasing the spillage thresholds from 0.2 to 1.0, simulated streamflow was reduced by 8.77 inches (from about 17.88 to 9.11 inches; 49 percent) for the 18-year period. During water years 1994-98, simulated annual streamflows for open-wetland spillage thresholds of 1.0 remained less than for thresholds of 0.2 even though the open wetlands probably were near maximum volume. The greatly increased size of the closed wetlands during water years 1994-98 probably allowed for increased water storage and decreased simulated streamflow from the study area.

Water-Resources Investigations Report↗

USGS2003

Estimating water temperatures in small streams in western Oregon using neural network models

Artificial neural network models were developed to estimate water temperatures in small streams using data collected at 148 sites throughout western Oregon from June to September 1999. The sites were located on 1st-, 2nd-, or 3rd-order streams having undisturbed or minimally disturbed conditions. Data collected at each site for model development included continuous hourly water temperature and description of riparian habitat. Additional data pertaining to the landscape characteristics of the basins upstream of the sites were assembled using geographic information system (GIS) techniques. Hourly meteorological time series data collected at 25 locations within the study region also were assembled. Clustering analysis was used to partition 142 sites into 3 groups. Separate models were developed for each group. The riparian habitat, basin characteristic, and meteorological time series data were independent variables and water temperature time series were dependent variables to the models, respectively. Approximately one-third of the data vectors were used for model training, and the remaining two-thirds were used for model testing. Critical input variables included riparian shade, site elevation, and percentage of forested area of the basin. Coefficient of determination and root mean square error for the models ranged from 0.88 to 0.99 and 0.05 to 0.59 oC, respectively. The models also were tested and validated using temperature time series, habitat, and basin landscape data from 6 sites that were separate from the 142 sites that were used to develop the models. The models are capable of estimating water temperatures at locations along 1st-, 2nd-, and 3rd-order streams in western Oregon. The model user must assemble riparian habitat and basin landscape characteristics data for a site of interest. These data, in addition to meteorological data, are model inputs. Output from the models include simulated hourly water temperatures for the June to September period. Adjustments can be made to the shade input data to simulate the effects of minimum or maximum shade on water temperatures.

Water-Resources Investigations Report↗

USGS2003

Development of regression equations to estimate flow durations and low-flow-frequency statistics in New Hampshire streams

Regression equations and basin-characteristic digital datasets were developed to help water-resource managers estimate surface-water resources during periods of low flow in New Hampshire. The regression equations were developed to estimate statistics for the seasonal and annual low-flow-frequency and seasonal period-of-record and period-of-record flow durations. Because streamflow is maintained by ground-water discharge during periods of low flow, these equations also will aid in the assessment of ground-water availability. Ultimately, the equations and datasets developed herein can be combined with data on water withdrawals, discharges, and interbasin transfers in a geographic information system (GIS) to allow assessments of water use and water availability in any drainage basin in the State of New Hampshire. Regression equations developed in this study provide estimates of the seasonal (spring, summer, fall, and winter) and annual 7-day 2-year (7Q2) and 7-day 10-year (7Q10) low-flow-frequency values, as well as seasonal period-of-record and period-of-record flow durations (60-, 70-, 80-, 90-, 95-, and 98-percent exceedences) for ungaged reaches of unregulated New Hampshire streams. Regression equations were developed using seasonal and annual low-flow statistics from 58 to 60 continuous-record stream-gaging stations in New Hampshire and nearby areas in neighboring states, and measurements of various characteristics of the drainage basins that contribute flow to those stations. The estimating equations for the seasonal and annual 7Q2 and 7Q10 values were developed using generalized-least-squares (GLS) regression analyses. The GLS equations developed for these flow statistics gave average prediction errors that ranged from 11 to 61 percent. The estimating equations for flow-duration exceedence frequency values were developed using ordinary-least-squares (OLS) regression analysis. The OLS equations developed for these flow statistics gave average prediction errors ranging from 14 to 79 percent. A total of 93 measurable drainage-basin characteristics were selected as possible predictor variables. Of these 93 variables, the following 10 were determined to be statistically significant predictors for at least one of the dependent variables: drainage area, average basin slope, maximum basin elevation, average summer gage precipitation for 1961-90, average spring gage precipitation for 1961-90, average mean annual basin temperature for 1961-90, average mean summer basin temperature for 1961-90, average winter basin-centroid precipitation for 1961-90, percent of the basin that is coniferous, and percent of the basin that is mixed coniferous and deciduous. These 10 basin characteristics were selected because they were statistically significant based on several statistical parameters that evaluated which combination of characteristics contributed the most to the predictive accuracy of the regression-equation models. A GIS is required to measure the values of the predictor variables for the equations developed in this study.

New Hampshire↗

USGS2003

Bathymetric mapping, sediment quality, and water quality of Lake Delhi, Iowa, 2001-02

Lake Delhi was formed in 1929 when the Interstate Power Company dammed the Maquoketa River near Delhi, Iowa, for generation of hydroelectric power. The resulting 450-acre lake became a popular area in eastern Iowa for boating, swimming, and fishing. Hydroelectric power generation ended in 1973, and lakeside residents purchased the dam to maintain the recreational opportunities of the lake. Increasing concerns about sediment deposition and water quality by lakeside residents led to a 2-year study that included a bathymetric survey, an assessment of sediment quality, and an assessment of water quality of Lake Delhi. A bathymetric map of Lake Delhi was constructed using more than 300,000 data points from echo sounding results and GIS (geographic information system) software. Results of bathymetric mapping showed that the upstream reach through most of the upstream-middle reach of Lake Delhi (approximately 3 miles) from about 0.25 mile upstream from the Greenslades coring site through Clair View Acres were particularly affected by sedimentation, with water depths ranging from less than 1 foot to a few areas that were as much as 10 feet deep. Numerous areas in the upstream-most 1-mile of the lake (about 0.25 mile upstream from the Greenslades coring site to just downstream from The Cedars coring site) had depths of only 1 to 2 feet and were nearly impassable by boats. The middle reach of Lake Delhi (an approximately 2.5-mile segment) from about one-half mile upstream from the Linden Acres coring site to just downstream from the Hartwick Dredge coring site was less affected by sedimentation with water depths from less than 1 to 16 feet. The deepest section (26 feet) of the lake was near the dam. Eleven trace metals and phosphorus were analyzed in 20 samples from seven lake-bottom sediment cores. The median and average traceelement concentrations from the sediment cores were less than the U.S. Environmental Protection Agency threshold-effects-level and probableeffects-level guidelines for toxic biological effects. Water-quality samples from eight sites (Maquoketa River, three lake sites, and four tributaries) were collected for five sampling periods (June 2001–July 2002). Water-quality samples were analyzed for physical properties (specific conductance, pH, temperature, turbidity, dissolved oxygen, and alkalinity), nutrients (nitrate, ammonia, and phosphorus), bacteria (total coliform and E. coli ), and suspended sediment. Selected water samples were analyzed for major ions, trace elements, and pesticides. Water-quality sampling results indicate areas affected by elevated nutrient and bacteria concentrations in the lake and tributary streams. The tributary streams had the highest median nitrate concentrations (12.1 milligrams per liter) when compared to median nitrate concentrations in the lake (8.7 milligrams per liter) or the Maquoketa River (10.5 milligrams per liter). The maximum nitrate concentrations detected for Maquoketa River, lake, and tributary sites were 13.5, 13.5, and 18.6 milligrams per liter, respectively. Nitrate concentrations in the late summer decreased from 2 Bathymetric Mapping, Sediment Quality, and Water Quality of Lake Delhi, Iowa, 2001–02 the upstream (7.8 milligrams per liter) to the downstream (5.0 milligrams per liter) one-third of Lake Delhi and most likely were the result of uptake of nitrate by algae and aquatic biota in the lake. Median concentrations of total coliform and E. coli bacteria for the lake sites were 450 and 17 colonies per 100 milliliters of sample, respectively. The U.S. Environmental Protection Agency criteria for full body contact (swimming or bathing) are 200 colonies per 100 milliliters for fecal bacteria and 126 colonies per 100 milliliters for E. coli bacteria. The highest bacteria concentrations in the lake occurred after a rain and were 25,000 colonies per 100 milliliters total coliform and 1,900 colonies per 100 milliliters E. coli .

Iowa↗

USGS2003

Sedimentation Survey of Lago El Guineo, Puerto Rico, October 2001

Lago El Guineo has lost about 17.5 percent of its original storage capacity in 70 years because of sediment accumulation. The water volume has been reduced from 2.29 million cubic meters in 1931, to 2.03 million cubic meters in 1986, and to 1.89 million cubic meters in 2001. The average annual storage-capacity loss (equal to the sedimentation rate) of Lago El Guineo was 4,727 cubic meters for the period of 1931 to July 1986 (or 0.21 percent per year), increasing to 5,714 cubic meters for the period of 1931 to October 2001 (or 0.25 percent per year). Discrepancies that could lead to substantial errors in volume calculations in a small reservoir like Lago El Guineo, were found when transferring the field-collected data into the geographic information system data base 1:20,000 U.S. Geological Survey Jayuya, Puerto Rico quadrangle. After verification and validation of field data, the Lago El Guineo shoreline was rectified using digital aerial photographs and differential global positioning data.

Water-Resources Investigations Report↗

USGS2003

Peak-flow characteristics of Wyoming streams

Peak-flow characteristics for unregulated streams in Wyoming are described in this report. Frequency relations for annual peak flows through water year 2000 at 364 streamflow-gaging stations in and near Wyoming were evaluated and revised or updated as needed. Analyses of historical floods, temporal trends, and generalized skew were included in the evaluation. Physical and climatic basin characteristics were determined for each gaging station using a geographic information system. Gaging stations with similar peak-flow and basin characteristics were grouped into six hydrologic regions. Regional statistical relations between peak-flow and basin characteristics were explored using multiple-regression techniques. Generalized least squares regression equations for estimating magnitudes of annual peak flows with selected recurrence intervals from 1.5 to 500 years were developed for each region. Average standard errors of estimate range from 34 to 131 percent. Average standard errors of prediction range from 35 to 135 percent. Several statistics for evaluating and comparing the errors in these estimates are described. Limitations of the equations are described. Methods for applying the regional equations for various circumstances are listed and examples are given.

Wyoming↗