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At least 1,351 records · Page 75Linked to original sources

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↗

USGS2016

Generalized sediment budgets of the Lower Missouri River, 1968–2014

Sediment budgets of the Lower Missouri River were developed in a study led by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers. The scope of the study included the development of a long-term (post-impoundment, 1968–2014) average annual sediment budget and selected annual, monthly, and daily sediment budgets for a reach and period that adequate data were available. Included in the analyses were 31 main-stem and tributary stations of the Lower Missouri River and two Mississippi River stations—the Mississippi River below Grafton, Illinois, and the Mississippi River at St. Louis, Missouri. Long-term average annual suspended-sediment loads of Missouri River main-stem stations ranged from 0.33 million tons at the Missouri River at Yankton, South Dakota, station to 71.2 million tons at Missouri River at Hermann, Mo., station. Gaged tributary gains accounted for 9–36 percent of the local reach budgets and cumulative gaged tributary contributions accounted for 84 percent of the long-term average suspended-sediment load of the Missouri River at Hermann, Mo., station. Although the sediment budgets for seven defined main-stem reaches generally were incomplete—missing bedload, reach storage, and ungaged tributary contributions—the budget residuals (net result of sediment inputs and outputs) for six of the seven reaches ranged from -7.0 to 1.7 million tons, or from -9.2 to 4.0 percent of the reach output suspended-sediment load, and were within the 10 percent reported measurement error of annual suspended-sediment loads for large rivers. The remaining reach, downstream from Gavin’s Point Dam, extended from Yankton, S. Dak., to Sioux City, Iowa, and had a budget residual of -9.8 million tons, which was -88 percent of the suspended-sediment load at Sioux City. The Lower Missouri River reach from Omaha, Nebraska, to Nebraska City, Nebr., had periods of concurrent sediment data for each primary budget component with which to analyze and determine a suspended-sediment budget for selected annual, monthly, and daily time increments. The temporal changes in the cumulative annual budget residuals were poorly correlated with the comparatively steady 1968–2011 annual stage trends at the Missouri River at Nebraska City, Nebr., station. An accurate total sediment budget is developed by having concurrent data available for all primary suspended and bedload components for a reach of interest throughout a period. Such a complete budget, with concurrent record for suspended-sediment load and bedload components, is unavailable for any reach and period in the Lower Missouri River. The primary data gaps are in bedload data, and also in suspended-sediment gains and losses including ungaged tributary inputs and sediment storage. Bedload data gaps in the Missouri River Basin are much more prevalent than suspended-sediment data gaps, and the first step in the development of reach bedload budgets is the establishment of a standardized bedload monitoring program at main-stem stations. The temporal changes in flow-adjusted suspended-sediment concentrations analyzed at main-stem Missouri River stations indicated an overall downward change in concentrations between 1968 and 2014. Temporary declines in flow-adjusted suspended-sediment concentrations during and following large floods were evident but generally returned to near pre-flood values within about 6 months. Data uncertainties associated with the development of a sediment budget include uncertainties associated with the collection of suspended-sediment and bedload data and the computation of suspended-sediment loads. These uncertainties vary depending on the frequency of data collection, the variability of conditions being represented by the discrete samples, and the statistical approach to suspended-sediment load computations. The coefficients of variation of suspended-sediment loads of Missouri River tributary stations for 1968–2014 were greater, 75.0 percent, than the main-stem stations, 47.1 percent. The lower coefficient of variation at main-stem stations compared to tributaries, primarily is the result of the lower variability in streamflow and sediment discharge identified at main-stem stations. To obtain similar accuracy between suspended-sediment loads at main-stem and tributary stations, a longer period of record is required of the tributary stations. During 1968–2014, however, the Missouri River main-stem station record was much more complete (87 percent) than the tributary station record (28 percent).

Missouri River Basin↗

USGS1983

Uncertainties in records of annual mean discharge in Maine

This report documents the results of rating analyses of flow during periods of ice-cover at 33 stations on selected rivers in Maine. Results were obtained through linear multiple regression. It also presents functions relating uncertainties in records to the number of discharge measurements made at these and 21 other stations. The application is unusual in that it includes analysis of the uncertainty of discharge as affected by backwater from ice. Total uncertainty consists of errors incurred during measurement and during data processing. An average of 46.8 percent of the total variance for the 21 stations not affected by backwater was due to measurement variance, and 53.2 percent was due to process variance. Data from the remaining 33 stations were divided into summer (open-water) periods and the winter (backwater) periods. An average of 49.3 percent of the total variance for the summer-period stations was due to measurements variance; 50.7 percent was due to process variance. An average of 25.2 percent of the total variance for the winter-period stations was due to measurement variance; 74.8 percent was due to process variance. Results of the seasonal division of average variance suggest that the process and measurement variances are essentially equal during open-water periods and that process variance is considerably greater than the measurement variance during backwater periods. The errors in winter discharge records significantly increased average uncertainty in the records of annual mean discharge. (USGS)

Water-Resources Investigations Report↗

USGS2020

Observed and modeled mercury and dissolved organic carbon concentrations and loads at control structure S-12D, Florida Everglades, 2013–17

Mercury (Hg) has been a contaminant of concern for several decades in South Florida, particularly in the Florida Everglades. The transport and bioavailability of Hg in aquatic systems is intimately linked to dissolved organic carbon (DOC). In aquatic systems, Hg can be converted to methylmercury (MeHg), which is the form of Hg that bioaccumulates in food webs. The bioaccumulation of MeHg poses significant health risks to wildlife and humans. Fish consumption advisories triggered by elevated Hg levels first appeared in the 1980s in South Florida. Multiple structures regulate freshwater distribution to Everglades National Park, including S-12D. This report summarizes seasonal and annual concentration and load data from late September 2013 to April 2017 for the total of (1) filter-passing total mercury (FTHg), (2) filter-passing methylmercury (FMeHg), (3) particulate total mercury (PTHg), (4) particulate methylmercury (PMeHg) and, (5) DOC discharged through control structure S-12D. The loads of Hg fractions and DOC at control structure S-12D were determined by pairing discharge data with constituent concentrations estimated by empirical models based on surrogate in situ water-quality measurements. Calculated concentrations of DOC ranged from 12.8 milligrams per liter (mg/L) to 27.9 mg/L with a mean of 18.8 mg/L during the study period. Annual loads of DOC ranged from 3,950 tons in 2015 to 10,900 tons in 2016. DOC loads increased linearly with an increase in flow, and the highest monthly DOC load of 1,630 tons was observed in February 2016. Calculated concentrations of FTHg ranged from 0.35 to 1.55 nanograms per liter (ng/L) with a mean of 0.85 ng/L during the study period. Calculated concentrations of FMeHg ranged from 0.06 ng/L to 0.24 ng/L with a mean of 0.14 ng/L during the study period. Generally, FTHg and FMeHg concentrations were lower during periods of decreased flow and higher during periods of increased flow. Calculated PTHg concentrations ranged from 0.09 ng/L to 4.19 ng/L with a mean of 0.58 ng/L during the study period. Calculated PMeHg concentrations ranged from below the limit of detection <0.01 ng/L to 0.29 ng/L with a mean of 0.03 ng/L during the study period. Loads of Hg were often zero or lowest from November to May, owing to the lack of flow or low-flow conditions. FTHg and FMeHg loads increased linearly with an increase in flow and typically were highest from June to October. During periods of increasing flow or following changes in gate operations, PTHg and PMeHg constituted a greater percentage of the total Hg load. Annual loads of total Hg (filter-passing and particulate) ranged from 254 grams in 2015 to 658 grams in 2016. FTHg was the predominant contributor to the total Hg load. Information presented herein provides the first assessment of DOC and Hg loads to Everglades National Park through control structure S-12D using continuous in situ measurements of discharge and constituent surrogates and compares the surrogate model approach to loads calculated from monthly sampling. Analysis of calculated and observed loads demonstrates the significance of flow data on calculating constituent loads.

Florida↗

USGS2025

Estimating flood discharges at selected annual exceedance probabilities for unregulated, rural streams in Vermont, 2023

This report provides estimates of flood discharge at selected annual exceedance probabilities (AEPs) for streamgages in and adjacent to Vermont and equations for estimating flood discharges at AEPs of 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent (recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, and 500-years, respectively) for ungaged, unregulated, rural streams in Vermont with drainage areas between 0.47 and 851 square miles. The equations were developed using generalized least-squares regression and flood-frequency and drainage-basin characteristics from 156 streamgages. Flood-frequency analyses were completed using data through the 2023 water year. The drainage-basin characteristics used as explanatory variables in the regression equations are drainage area, percentage of wetland area, and basin-wide mean of the average annual precipitation. The average standard errors of prediction used to estimate flood discharges at the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEP with these equations are 34.9, 37.1, 38.2, 41.6, 43.8, 46.0, 49.1, and 53.2 percent, respectively. Flood discharges at selected AEPs for streamgages were computed using the Expected Moments Algorithm. Techniques used to adjust an AEP discharge computed from a streamgage record with results from the regression equations and to estimate flood discharge at a selected AEP for an ungaged site upstream or downstream from a streamgage using a drainage-area adjustment are both described. The final regression equations and the flood-discharge frequency data used in this study will be available in StreamStats. StreamStats is an internet-based application that provides automated regression-equation solutions for user-selected sites on streams.

Vermont↗

USGS2011

Gas shale/oil shale

The production of natural gas from shales continues to increase in North America, and shale gas exploration is on the rise in other parts of the world since the previous report by this committee was published by American Association of Petroleum Geologists, Energy Minerals Division (2009). For the United States, the volume of proved reserves of natural gas increased 11% from 2008 to 2009, the increase driven largely by shale gas development (Energy Information Administration 2010c). Furthermore, shales have increasingly become targets of exploration for oil and condensate as well as gas, which has served to greatly expand their significance as ‘‘unconventional’’ petroleum reservoirs. This report provides information about specific shales across North America and Europe from which gas (biogenic or thermogenic), oil, or natural gas liquids are produced or is actively being explored. The intent is to reflect the recently expanded mission of the Energy Minerals Division (EMD) Gas Shales Committee to serve as a single point of access to technical information on shales regardless of the type of hydrocarbon produced from them. The contents of this report were drawn largely from contributions by numerous members of the EMD Gas Shales Advisory Committee, with much of the data being available from public websites such as state or provincial geological surveys or other public institutions. Shales from which gas or oil is being produced in the United States are listed in alphabetical order by shale name. Information for Canada is presented by province, whereas for Europe, it is presented by country.

Natural Resources Research↗

USGS2026

Improving estimates of spatially distributed agricultural land use using pesticide data

Accurate, spatially resolved agricultural land-use data are essential for estimating water demand, evaluating agricultural production, and understanding long-term changes in managed landscapes. However, existing land-use datasets are often temporally discontinuous, particularly for historical periods, and remotely sensed classifications face persistent challenges distinguishing spectrally similar crop types, capturing sub-annual rotations, and separating active from abandoned plantings. We developed the California Pesticide Use Reporting Land-Use Estimator (CalPUR-LUE), which converts grower-reported pesticide-application records into annual estimates of land use by crop class and cropped acreage at approximately 1-square-mile resolution across California. CalPUR-LUE performance was evaluated for 2018 using complementary spatial, categorical, and quantitative comparisons with California Department of Water Resources (CADWR) remotely sensed land-use data and county-level agricultural economic reports. At the county-meridian-township-range-section (COMTRS) scale, CalPUR-LUE and CADWR acreage estimates showed substantial proportional agreement (log-transformed Lin’s concordance correlation coefficient = 0.77) with a mean proportional bias of −15%. Crop-class agreement was high when CalPUR-LUE identified agricultural activity, with user’s accuracy exceeding 83% for all evaluated crop classes. Overall categorical agreement was 67% (Cohen’s kappa = 0.56). Grain crop underestimation contributed substantially to disagreement; however, there is evidence of CADWR systematic overestimation of grain during 2016–2019. County-level agricultural reports further corroborated CalPUR-LUE estimates and, in several cases, aligned more closely with CalPUR-LUE than with CADWR. These results demonstrate that pesticide-use reporting provides an independent and complementary source of agricultural land-use information that can corroborate contemporary estimates and reconstruct annual spatially distributed land use where historical data are limited.

California↗

USGS2005

Water, ice, and meteorological measurements at South Cascade glacier, Washington, balance year 2003

Winter snow accumulation and summer snow and ice ablation were measured at South Cascade Glacier, Washington, to estimate glacier mass-balance quantities for balance year 2003. The 2003 glacier-average maximum winter snow balance was 2.66 meters water equivalent, which was about equal to the average of such balances for the glacier since balance year 1959. The 2003 glacier summer balance (-4.76 meters water equivalent) was the most negative reported for the glacier, and the 2003 net balance (-2.10 meters water equivalent), was the second-most negative reported. The glacier 2003 annual (water year) balance was -1.89 meters water equivalent. The area of the glacier near the end of the balance year was 1.89 square kilometers, a decrease of 0.03 square kilometer from the previous year. The equilibrium-line altitude was higher than any part of the glacier; however, because snow remained along part of one side of the upper glacier, the accumulation-area ratio was 0.07. During September 13, 2002-September 13, 2003, the glacier terminus retreated at a rate of about 15 meters per year. Average speed of surface ice, computed using a series of vertical aerial photographs dating back to 2001, ranged from 2.2 to 21.8 meters per year. Runoff from the subbasin containing the glacier and from an adjacent non-glacierized basin was gaged during part of water year 2003. Air temperature, precipitation, atmospheric water-vapor pressure, wind speed, and incoming solar radiation were measured at selected locations on and near the glacier. Summer 2003 at the glacier was among the warmest for which data are available.

Scientific Investigations Report↗

USGS2003

Rocky Mountain snowpack chemistry at selected sites for 2001

Because regional-scale atmospheric deposition data in the Rocky Mountains are sparse, a program was designed by the U.S. Geological Survey, in cooperation with the National Park Service, U.S. Department of Agriculture Forest Service, and other agencies, to more thoroughly determine the chemical composition of precipitation and to identify sources of atmospherically deposited contaminants in a network of high-elevation sites. Samples of seasonal snowpacks at 57 geographically distributed sites, in a regional network from New Mexico to Montana, were collected and analyzed for major ions (including ammonium, nitrate, and sulfate), alkalinity, and dissolved organic carbon during 2001. Sites selected in this report have been sampled annually since 1993, enabling identification of increases or decreases in chemical concentrations from year to year. Spatial patterns in snowpack-chemical data for concentrations of ammonium, nitrate, and sulfate indicate that concentrations of these acid precursors in less developed areas of the region are lower than concentrations in the heavily developed areas. Results for the 2001 snowpack-chemistry analyses, however, indicate increases in concentrations of ammonium and nitrate in particular at sites where past concentrations typically were lower. Since 1993, concentrations of nitrate and sulfate were highest from snowpack samples in northern Colorado that were collected from sites adjacent to the Denver metropolitan area to the east and the coal-fired powerplants to the west. In 2001, relatively high concentrations of nitrate (12.3 to 23.0 microequivalents per liter (µeq/L) and sulfate (7.7 to 12.5 µeq/L) were detected in Montana and Wyoming. Ammonium concentrations were highest in north-central Colorado (14.5 to 16.9 µeq/L) and southwestern Montana (12.8 to 14.2 µeq/L).

Rocky Mountains↗

USGS1925

Variation in annual run-off in the Rocky Mountain region: Chapter A in Contributions to the hydrology of the United States, 1923-1924

Records of run-off in the Rocky Mountain States since the nineties and for a few stations since the eighties afford a means of studying the variation in the annual run-off in this region. The data presented in this report show that the variation in annual run-off differs in different areas in the Rocky Mountain region, owing to the differences in the sources of the precipitation in these areas. Except in the drainage basins of streams in northern Montana the year of lowest run-off shown by the records was 1902, when the run-ff at one station was only 36 per cent of the mean run-ff for the periods covered by the several records available. The percentage variation of run-ff for streams in different parts of Colorado is less for any one year than that for streams in the mountain region as a whole, and for streams in the same major drainage basin the annual variation is markedly similar. The influence of topography upon variation in annual run-ff for streams in Colorado is marked, the streams that rise in the central mountain region having a smaller range in variation than the streams that rise on the eastern or western edges of the central mountain mass. The streams that rise on the plains just east of the mountains have a greater variation than those of any of the mountain groups. The ratio of any 10-year mean to the mean for the entire period covered by the records ranges from 72 to 133 per cent. For the South Platte, Arkansas, and Rio Grande the run-off during the nineties was below the normal, but since about 1903 it has been above normal. For the Cache la Poudre low-water periods occurred during the eighties and from 1905 to 1922, but during the nineties the run-off was above the normal.

Colorado;Montana;Wyoming↗

USGS2023

Estimating peak-flow quantiles for selected annual exceedance probabilities in Illinois

This report presents the methods, results, and applications of an updated flood-frequency study for the State of Illinois. This study, which uses data through September 2017, updates two previous studies that used data through 1999 and 2009, respectively. Flood-frequency estimates are used for a variety of land-use planning and infrastructure design purposes, including for the hydraulic design of bridges. The flood frequencies presented are the stream discharges (or quantiles) that are exceeded each year with a given probability, called the annual exceedance probability (AEP). Estimates are provided for eight AEPs: 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002. The basic data used are the annual maximum discharges (peak flows) at streamgages in and near Illinois and the measurable physical properties (basin characteristics) of the basins upstream from those streamgages. The logarithms of the peak flow records at qualifying streamgages were fit to the Pearson Type 3 distribution using federally recommended methods, providing one of the two primary products of the study, which is the set of peak-flow quantiles at the streamgages and their uncertainties. The other primary product is sets of equations, determined by least-squares regression, that relate the peak-flow quantiles and the basin characteristics. There is one set of equations for each of Illinois’ seven hydrologic regions, and, for each region, one equation for each AEP. These regional equations allow the estimation of peak-flow quantiles at ungaged locations throughout the state and their uncertainties. A set of illustrative example applications is provided, and tables of all results at all study streamgages and regions are provided in associated data releases. The study results are also being made available in a web application, StreamStats.

Illinios↗

USGS2004

Proceedings of the twentieth annual meeting of the Society for Organic Petrology

The Society for Organic Petrology (TSOP; pronounced "Tee'-sop") was established in 1984 to consolidate and foster the organizational activities of scientists and engineers involved with coal petrology, kerogen petrology, organic geochemistry, and related disciplines. The following report, "Proceedings of the Twentieth Annual Meeting of The Society for Organic Petrology" (ISSN 1060-7250), features technical talks, poster presentations, business meetings, short courses, and field trips from the Fall 2003 annual meeting held in Washington, D.C.

Open-File Report↗

USGS2014

Flow‐duration characteristics of Illinois streams

The paper entitled “An investigation of the flow‐duration characteristics of North Carolina streams,” by Thorndlke Saville and John Dargan Watson, which was published by the American Geophysical Union in its report of the Fourteenth Annual Meeting in 1933 (pp. 406–425), stimulated the writer, who is familiar with the streams discussed, having been assigned for several years to the United States Geological Survey offices that collected the base data. Knowing that there is a marked similarity in runoff‐characteristics of the western North Carolina streams and also that fairly good similarity is shown by New England streams within reasonable zones, he felt it would be desirable to carry the investigation to a part of the country where stream‐flow characteristics are diverse. The present investigation was therefore made to cover all the long‐time records in Illinois on streams of definite drainage‐area, particular attention being paid to comparisons of records from the same stream. The record on the Rock River at Afton, Wisconsin, was also included. The streams studied are listed in Table 1.

Illinois↗

USGS2017

Maintenance of influenza A viruses and antibody response in mallards (Anas platyrhynchos) sampled during the non-breeding season in Alaska

Prevalence of influenza A virus (IAV) infections in northern-breeding waterfowl has previously been reported to reach an annual peak during late summer or autumn; however, little is known about IAV infection dynamics in waterfowl populations persisting at high-latitude regions such as Alaska, during winter. We captured mallards ( Anas platyrhynchos ) throughout the non-breeding season (August–April) of 2012–2015 in Fairbanks and Anchorage, the two largest cities in Alaska, to assess patterns of IAV infection and antibody production using molecular methods and a standard serologic assay. In addition, we used virus isolation, genetic sequencing, and a virus microneutralization assay to characterize viral subtypes and to evaluate the immune response of mallards captured on multiple occasions through time. We captured 923 mallards during three successive sampling years: Fairbanks in 2012/13 and 2013/14, and Anchorage in 2014/15. Prevalence varied by age, season, and year/site with high and relatively stable estimates throughout the non-breeding season. Infected birds were detected in all locations/seasons except early-winter in Fairbanks during 2013/14. IAVs with 17 combinations of hemagglutinin (H1–5, H7–9, H11, H12) and neuraminidase (N1–6, N8, N9) subtypes were isolated. Antibodies to IAVs were detected throughout autumn and winter for all sampling locations and years, however, seroprevalence was higher among adults and varied among years. Mallards exhibited individual heterogeneity with regard to immune response, providing instances of both seroconversion and seroreversion to detected viral subtypes. The probability that an individual transitioned from one serostatus to another varied by age, with juvenile mallards having higher rates of seroconversion and seroreversion than adults. Our study provides evidence that a diversity of IAVs circulate in populations of mallards wintering at urban locations in Alaska, and we suggest waterfowl wintering at high-latitudes may play an important role in maintenance of viruses across breeding seasons.

Alaska↗

USGS1981

Hydrology of area 4, Eastern Coal Province, Pennsylvania, Ohio, and West Virginia

Area 4 (one of the 24 hydrologic areas defining the Eastern Coal Province) is located at the northern end of the Eastern Coal Province in eastern Ohio, northern West Virginia, and western Pennsylvania. It is part of the upper Ohio River basin, which includes the Beaver, Mahoning, and Shenango Rivers. The area is underlain by rocks of the Pottsville, Allegheny, Conemaugh, Monongahela Groups (or Formations) and Dunkard Group. Area 4 has a temperate climate with an annual average rainfall of 38 to 42 inches, most of its area is covered by forest. The soils have a high erosion potential where the vegetation cover is removed. In response to Public Law 95-87, 132 sites were added to the existing surface-water data-collection network in area 4. At these added sites, collected data includes discharge, water quality, sediment, and biology. The data are available from computer storage through the National Water Data Exchange (NAWDEX) or the published annual Water Resources Data reports for Ohio, Pennsylvania, and West Virginia. Hydrologic problems related to mining are: (1) Erosion and increased sedimentation, and (2) degradation of water quality. Erosion and sedimentation are associated chiefly with surface mining. Sediment yields increase drastically when vegetation is removed from the highly erosive soils. Degradation of water quality can be caused by acid-mine drainage from underground and surface mining. More than half the acid-mine drainage effluent in area 4 comes from underground mines. The rest seeps from abandoned surface mines. Usually in reclaimed surface mines the overburden is replaced in such a short time after the coal is taken out that oxidation of acid-forming minerals, commonly pyrite or marcasite, is not complete or is neutralized by the buffering action of calcareous minerals in the soils. (USGS)

Open-File Report↗

USGS1982

Development of ground-water resources in Orange County, Texas, and adjacent areas in Texas and Louisiana, 1971-80

Pumpage in Orange County from the lower unit of the Chicot aquifer averaged 21.2 million gallons per day (0.93 cubic meter per second) and pumpage from the upper unit of the Chicot averaged about 2 million gallons per day (0.088 cubic meter per second) from 1971-79. Annual pumpage increased in municipal areas and decreased in industrial areas with little net change in total annual pumpage during the report period. The major water-bearing unit in the study area is the Chicot aquifer, which overlies the Evangeline aquifer. The Evangeline aquifer is undeveloped in Orange County, but is developed at Evadale in Jasper County, Texas, and at Silsbee in Hardin County, Texas. Both aquifers consist of unconsolidated and discontinuous layers of sand and clay that gently dip toward the Gulf of Mexico. Water levels in Orange County tended to stabilize or rise in areas where ground-water withdrawals decreased. Elsewhere in Orange County, most water levels continued to decline, generally at a slower rate than before 1971. Bench-mark elevations determined during 1973 show regional land-surface subsidence from 1918-73, generally attributed to ground-water development, to be less than 0.5 foot (0.15 meter). Locally, subsidence due to production of oil, gas, saltwater, or sulfur was about 15 feet (4.6 meters) at Spindletop Dome, Jefferson County, Texas, and as much as 3 feet (1.0 meter) near Port Acres gas field, Jefferson County, Texas. Although saltwater encroachment is evident in parts of southern Orange County, the encroachment is not expected to be detrimental if the ground-water pumping remains stable and the projected increase in demands for water is met with surface-water supplies.

Louisiana, Texas↗

USGS2002

Measuring streamflow in Virginia (2002 revision)

The U.S. Geological Survey (USGS), U.S. Department of the Interior, is the Nation's largest Earth-science information agency. Among its many responsibilities, such as map making and providing information on earthquakes and other natural hazards, the USGS provides information on the Nation's water resources. The USGS has collected and analyzed hydrologic (water-related) information for more than 100 years. In 1889, the first streamflow-gaging station (a site where regular observations of streamflow data are collected) operated in the United States by the USGS was established on the Rio Grande near Embudo, New Mexico. As the need for streamflow data increased, the USGS's streamflow-gaging program has grown to include more than 7,000 continuous-record streamflow-gaging stations. More than 90 percent of these stations are operated with at least partial support from State, local, or other Federal agencies In Virginia, the Department of Environmental Quality (DEQ) is a major cooperator in the streamflow-gaging program, which consists of 161 continuous-record streamflow-gaging stations located throughout the State (fig. 1). The USGS and DEQ cooperate to publish the annual USGS State data report, 'Water Resources Data-Virginia'; this two-volume publication includes streamflow data collected at the 161 streamflow-gaging stations, chemical data collected at 19 streamflow-gaging stations, and ground-water data collected from more than 250 wells located in Virginia.

Virginia↗

USGS1999

Measuring streamflow in Virginia (1999 revision)

The U.S. Geological Survey (USGS), U.S. Department of the Interior, is the Nation's largest Earth-science information agency. Among its many responsibilities, such as map making and providing information on earthquakes and other natural hazards, the USGS provides information on the Nation's water resources. The USGS has collected and analyzed hydrologic (water-related) information for more than 100 years. In 1889, the first streamflow-gaging station (a site where regular observations of streamflow data are collected) operated in the United States by the USGS was established on the Rio Grande near Embudo, New Mexico. As the need for streamflow data increased, the USGS's streamflow-gaging program has grown to include more than 7,000 continuous-record streamflow-gaging stations. More than 90 percent of these stations are operated with at least partial support from State, local, and other Federal agencies. In Virginia, the Department of Environmental Quality (DEQ) is a major cooperator in the streamflow-gaging program, which consists of 152 continuous-record streamflow-gaging stations located throughout the State (fig. 1). The USGS and DEQ cooperate to publish the annual USGS State data report, "Water Resources Data-Virginia;" this two-volume publication includes streamflow data collected at the 152 streamflow-gaging stations, chemical data collected at more than 24 streamflow-gaging stations, and ground-water data collected from more than 338 wells.

Virginia↗