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At least 667 records · Page 37Linked to original sources
USGS1985

Water-level declines in the Amargosa Valley area, Nye County, Nevada, 1962-84

Groundwater flow in the Amargosa Valley area is in Nevada complex and involves a valley fill aquifer and an underlying carbonate rock aquifer. Groundwater development in the area is in the valley fill aquifer, about 10 mi. south-west of Lathrop Wells. Water levels measured in selected wells in the area in 1984 are lower than those measured in 1962, demonstrating that water levels have undergone a net decline since 1962. An implied water level rise and resulting groundwater mound suggested on a map from a U.S. Bureau of Reclamation report appear to be based on the inadvertent misplotting of two wells. Data presented in this report indicate that the implied mound does not exist. (Lantz-PTT)

Water-Resources Investigations Report↗
USGS1987

Comparison of irrigation pumpage and change in water storage of the High Plains Aquifer in Castro and Parmer counties, Texas, 1975-83

An understanding of the relationship between irrigation pumpage and change in ground-water storage was needed to quantify the amount of water returning to the High Plains aquifer as a result of intensive irrigation in Castro and Parmer Counties, Texas. Irrigation pumpage for the 9-year period, 1975-83, was estimated by using the Blaney-Criddle consumptive-use formula adjusted by a factor to account for irrigation demand and field-measured crop applications. Total estimated pumpage for the 9-year period was 11,269,000 acre-feet and 8,914,000 acre-feet. The estimated pumpage was based upon reported crop acreage data and LANDSAT acreage data, respectively. Aquifer storage for the same period was estimated as the product of specific yield, net water-level change, and area. Change in storage was 5,168,000 acre-feet. Many of the areas of the largest change in storage also were the areas of the largest saturated thickness. The only locations that did not experience substantial water-level declines were the northwest and northeast parts of the study area. A comparison was made of water returning to the aquifer by calculating the difference between irrigation pumpage and the change in aquifer storage. Two estimates of this comparison, expressed as a percentage of irrigation pumpage, were obtained on the basis of two different sources of acreage data. This comparison was 54 percent of pumpage based on reported crop acreage data and 42 percent of pumpage based on LANDSAT interpreted acreage data.

Texas↗
USGS1987

US Geological Survey urban-stormwater data base of constituent storm loads; characteristics of rainfall, runoff, and antecedent conditions; and basin characteristics

A data base which consists of constituent storm loads, characteristics of rainfall, runoff, and antecedent conditions, and basin characteristics measured at most of the stations in the U.S. Geological Survey urban-stormwater data-collection network in metropolitan areas throughout the United States has been compiled. Tables of these constituents storm loads and characteristics are presented in this report. The data base also is available on magnetic tape. The data represent 1,144 storms at 97 stations in 21 metropolitan areas. Storm loads for 18 constituents and 15 characteristics of rainfall, runoff, and antecedent conditions are reported. Twenty-eight selected basin characteristics also are reported, including 11 categories of land use. (USGS)

Water-Resources Investigations Report↗
USGS1996

Prediction of traveltime and longitudinal dispersion in rivers and streams

The possibility of a contaminant being accidentally or intentionally spilled upstream from a water supply is a constant concern to those diverting and using water from streams and rivers. Although many excellent models are available to estimate traveltime and dispersion, none can be used with confidence before calibration and verification to the particular river reach in question. Therefore, the availability of reliable input information is usually the weakest link in the chain of events needed to predict the rate of movement, dilution, and mixing of contaminants in rivers and streams. Measured tracer-response curves produced from the injection of a known quantity of soluble tracer provide an efficient method of obtaining the necessary data. The purpose of this report is to use previously presented concepts along with extensive data collected on time of travel and dispersion to provide guidance to water-resources managers and planners in responding to spills. This is done by providing methods to estimate (1) the rate of movement of a contaminant through a river reach, (2) the rate of attenuation of the peak concentration of a conservative contaminant with time, and (3) the length of time required for the contaminant plume to pass a point in the river. Although the accuracy of the predictions can be greatly increased by performing time-oftravel studies on the river reach in question, the emphasis of this report is on providing methods for making estimates where few data are available. Results from rivers of all sizes can be combined by defining the unit concentration as that concentration of a conservative pollutant that would result from injecting a unit of mass into a unit of flow. Unit-peak concentrations are compiled for more than 60 different rivers representing a wide range of sizes, slopes, and geomorphic types. Analyses of these data indicate that the unitpeak concentration is well correlated with the time required for a pollutant cloud to reach a specific point in the river. The variance among different rivers is, of course, larger than for a specific river reach. Other river characteristics that were compiled and included in the correlation included the drainage area, the reach slope, the mean annual discharge, and the discharge at the time of the measurement. The most significant other variable in the correlation was the ratio of the river discharge to mean annual discharge. The prediction of the traveltime is more difficult than the prediction of unit-peak concentration; but the logarithm of stream velocity can be assumed to be linearly correlated with the logarithm of discharge. More than 980 subreaches for about 90 different rivers were analyzed and prediction equations were developed based on the drainage area, the reach slope, the mean annual discharge, and the discharge at the time of the measurement. The highest probable velocity, which will result in the highest concentration, is usually of concern after an accidental spill. Therefore, an envelope curve for which more than 99 percent of the velocities were smaller was developed to address this concern. The time of arrival of the leading edge of the pollutant indicates when a problem will first exist and defines the overall shape of the tracer-response function. The traveltime of the leading edge is generally about 89 percent of the traveltime to the peak concentration. The area under a tracer-response function (a known value when unit concentrations are used) can be closely approximated as the area under a triangle with a height of the peak concentration and a base extending from the leading edge to a point where the concentration has reduced to 1C percent of the peak. Knowing the time of the leading edge and the peak, the peak concentration, and the time when the response function has reduced to 10 percent of its peak value allows the complete response function to be sketched with fair accuracy. Four example applications are included to illustrate how the prediction equations developed in this report can be used either to calibrate a mathematical model or to make predictions directly.

Water-Resources Investigations Report↗
USGS2007

Mercury and methylmercury in water and bottom sediments of wetlands at Lostwood National Wildlife Refuge, North Dakota, 2003-04

Certain ecosystem types, particularly wetlands, have environmental characteristics that can make them particularly sensitive to mercury inputs and that can result in large mercury concentrations in fish or other aquatic biota. To provide information needed to make effective management decisions to decrease human and wildlife exposure to methylmercury in northern prairie pothole wetlands, the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, conducted a study to assess mercury and methylmercury concentrations in wetlands at the Lostwood National Wildlife Refuge (the Refuge) in northwest North Dakota. In April 2003 and 2004, water and bottom-sediment samples were collected from 44 individual wetlands that were classified as one of four wetland types. Many factors that may affect methylmercury production were considered in the study. The prairie pothole wetlands at the Refuge had large ranges in major environmental characteristics. Hydrologic differences, most notably semiannual wetting and drying cycles, that are intrinsic to prairie pothole wetlands affected methylmercury concentrations. This likely resulted from the stimulation of anaerobic microbial activity following reflooding of soils, particularly soils containing substantial organic carbon. Among the four wetland types considered for this study, seasonal and semipermanent wetlands generally had the largest methylmercury concentrations. Regardless of wetland type, however, methylmercury concentrations at the Refuge are large in relation to reported concentrations for natural aquatic systems.

North Dakota↗
USGS2008

Preliminary Volcano-Hazard Assessment for Gareloi Volcano, Gareloi Island, Alaska

Gareloi Volcano (178.794 degrees W and 51.790 degrees N) is located on Gareloi Island in the Delarof Islands group of the Aleutian Islands, about 2,000 kilometers west-southwest of Anchorage and about 150 kilometers west of Adak, the westernmost community in Alaska. This small (about 8x10 kilometer) volcano has been one of the most active in the Aleutians since its discovery by the Bering expedition in the 1740s, though because of its remote location, observations have been scant and many smaller eruptions may have gone unrecorded. Eruptions of Gareloi commonly produce ash clouds and lava flows. Scars on the flanks of the volcano and debris-avalanche deposits on the adjacent seafloor indicate that the volcano has produced large landslides in the past, possibly causing tsunamis. Such events are infrequent, occurring at most every few thousand years. The primary hazard from Gareloi is airborne clouds of ash that could affect aircraft. In this report, we summarize and describe the major volcanic hazards associated with Gareloi.

Scientific Investigations Report↗
USGS2011

Summary of the Georgia Agricultural Water Conservation and Metering Program and evaluation of methods used to collect and analyze irrigation data in the middle and lower Chattahoochee and Flint River basins, 2004-2010

Since receiving jurisdiction from the State Legislature in June 2003 to implement the Georgia Agricultural Water Conservation and Metering Program, the Georgia Soil and Water Conservation Commission (Commission) by year-end 2010 installed more than 10,000 annually read water meters and nearly 200 daily reporting, satellite-transmitted, telemetry sites on irrigation systems located primarily in southern Georgia. More than 3,000 annually reported meters and 50 telemetry sites were installed during 2010 alone. The Commission monitored rates and volumes of agricultural irrigation supplied by groundwater, surface-water, and well-to-pond sources to inform water managers on the patterns and amounts of such water use and to determine effective and efficient resource utilization. Summary analyses of 4 complete years of irrigation data collected from annually read water meters in the middle and lower Chattahoochee and Flint River basins during 2007-2010 indicated that groundwater-supplied fields received slightly more irrigation depth per acre than surface-water-supplied fields. Year 2007 yielded the largest disparity between irrigation depth supplied by groundwater and surface-water sources as farmers responded to severe-to-exceptional drought conditions with increased irrigation. Groundwater sources (wells and well-to-pond systems) outnumbered surface-water sources by a factor of five; each groundwater source applied a third more irrigation volume than surface water; and, total irrigation volume from groundwater exceeded that of surface water by a factor of 6.7. Metered irrigation volume indicated a pattern of low-to-high water use from northwest to southeast that could point to relations between agricultural water use, water-resource potential and availability, soil type, and crop patterns. Normalizing metered irrigation-volume data by factoring out irrigated acres allowed irrigation water use to be expressed as an irrigation depth and nearly eliminated the disparity between volumes of applied irrigation derived from groundwater and surface water. Analysis of per-acre irrigation depths provided a commonality for comparing irrigation practices across the entire range of field sizes in southern Georgia and indicated underreporting of irrigated acres for some systems. Well-to-pond systems supplied irrigation at depths similar to groundwater and can be combined with groundwater irrigation data for subsequent analyses. Average irrigation depths during 2010 indicated an increase from average irrigation depths during 2008 and 2009, most likely the result of relatively dry conditions during 2010 compared to conditions in 2008 and 2009. Geostatistical models facilitated estimation of irrigation water use for unmetered systems and demonstrated usefulness in redesigning the telemetry network. Geospatial analysis evaluated the ability of the telemetry network to represent annually reported water-meter data and presented an objective, unbiased method for revising the network.

Georgia↗
USGS2016

Effects of water-supply reservoirs on streamflow in Massachusetts

State and local water-resource managers need modeling tools to help them manage and protect water-supply resources for both human consumption and ecological needs. The U.S. Geological Survey, in cooperation with the Massachusetts Department of Environmental Protection, has developed a decision-support tool to estimate the effects of reservoirs on natural streamflow. The Massachusetts Reservoir Simulation Tool is a model that simulates the daily water balance of a reservoir. The reservoir simulation tool provides estimates of daily outflows from reservoirs and compares the frequency, duration, and magnitude of the volume of outflows from reservoirs with estimates of the unaltered streamflow that would occur if no dam were present. This tool will help environmental managers understand the complex interactions and tradeoffs between water withdrawals, reservoir operational practices, and reservoir outflows needed for aquatic habitats. A sensitivity analysis of the daily water balance equation was performed to identify physical and operational features of reservoirs that could have the greatest effect on reservoir outflows. For the purpose of this report, uncontrolled releases of water (spills or spillage) over the reservoir spillway were considered to be a proxy for reservoir outflows directly below the dam. The ratio of average withdrawals to the average inflows had the largest effect on spillage patterns, with the highest withdrawals leading to the lowest spillage. The size of the surface area relative to the drainage area of the reservoir also had an effect on spillage; reservoirs with large surface areas have high evaporation rates during the summer, which can contribute to frequent and long periods without spillage, even in the absence of water withdrawals. Other reservoir characteristics, such as variability of inflows, groundwater interactions, and seasonal demand patterns, had low to moderate effects on the frequency, duration, and magnitude of spillage. The reservoir simulation tool was used to simulate 35 single- and multiple-reservoir systems in Massachusetts over a 44-year period (water years 1961 to 2004) under two water-use scenarios. The no-pumping scenario assumes no water withdrawal pumping, and the pumping scenario incorporates average annual pumping rates from 2000 to 2004. By comparing the results of the two scenarios, the total streamflow alteration can be parsed into the portion of streamflow alteration caused by the presence of a reservoir and the additional streamflow alteration caused by the level of water use of the system. For each reservoir system, the following metrics were computed to characterize the frequency, duration, and magnitude of reservoir outflow volumes compared with unaltered streamflow conditions: (1) the median number of days per year in which the reservoir did not spill, (2) the median duration of the longest consecutive period of no-spill days per year, and (3) the lowest annual flow duration exceedance probability at which the outflows are significantly different from estimated unaltered streamflow at the 95-percent confidence level. Most reservoirs in the study do not spill during the summer months even under no-pumping conditions. The median number of days during which there was no spillage was less than 365 for all reservoirs in the study, indicating that, even under reported pumping conditions, the reservoirs refill to full volume and spill at least once during nondrought years, typically in the spring. Thirteen multiple-reservoir systems consisting of two or three hydrologically connected reservoirs were included in the study. Because operating rules used to manage multiple-reservoir systems are not available, these systems were simulated under two pumping scenarios, one in which water transfers between reservoirs are minimal and one in which reservoirs continually transferred water to intermediate or terminal reservoirs. These two scenarios provided upper and lower estimates of spillage under average pumping conditions from 2000 to 2004. For sites with insufficient data to simulate daily water balances, a proxy method to estimate the three spillage metrics was developed. A series of 4,000 Monte Carlo simulations of the reservoir water balance were run. In each simulation, streamflow, physical reservoir characteristics, and daily climate inputs were randomly varied. Tobit regression equations that quantify the relation between streamflow alteration and physical and operational characteristics of reservoirs were developed from the results of the Monte Carlo simulations and can be used to estimate each of the three spillage metrics using only the withdrawal ratio and the ratio of the surface area to the drainage area, which are available statewide for all reservoirs. A graphical user-interface for the Massachusetts Reservoir Simulation Tool was developed in a Microsoft Access environment. The simulation tool contains information for 70 reservoirs in Massachusetts and allows for simulation of additional scenarios than the ones considered in this report, including controlled releases, dam seepage and leakage, demand management plans, and alternative water withdrawal and transfer rules.

Massachusetts↗
USGS2026

Streamflow characterization and effects of Interstate 26 highway construction on water-quality and channel morphology conditions of the French Broad River in Buncombe and Henderson Counties, North Carolina, 2019–22

The North Carolina Department of Transportation began a series of highway construction projects to upgrade Interstate 26 (I–26) in Buncombe and Henderson Counties, North Carolina, starting in early 2020. The North Carolina Department of Transportation and the U.S. Geological Survey partnered in 2019 to monitor and assess water-quality and geomorphic conditions throughout the French Broad River corridor in areas near Interstate 26 highway construction activities. This report summarizes findings from multi-year water-quality and channel morphology monitoring from 2019 through 2022 in the French Broad River corridor near ongoing highway construction activities. Dissolved oxygen, pH, specific conductance, turbidity, and water temperature were monitored at six gaging locations, three of which were near highway sections undergoing construction during the study period from June 1, 2019, through December 31, 2022. Water quality was compared across three monitoring locations before and during construction using Brunner-Dette-Munk statistical tests, a nonparametric form of analysis of variance used for unbalanced datasets. Most Brunner-Dette-Munk test results detected insignificant effects of highway construction on water-quality conditions when controlling for monitoring location, except for the test of daily maximum specific conductance values. However, the effects of highway construction could not be isolated from other external factors that may have affected specific conductance, including an extended period of low streamflow and possible road salt application after winter storms. Additional Brunner-Dette-Munk tests, controlling for flow magnitude (streamflow quantiles) or hydrograph position (“rising limb,” “falling limb,” or “base flow”), did not suggest that highway construction affected water-quality conditions in the study area. Geomorphic surveys of the streambed and streambanks were performed in a 1-kilometer reach from 2019 through 2022 to assess geomorphic changes during the reconstruction of a bridge spanning the French Broad River. Bathymetric surveys of the streambed and light detection and ranging (lidar) scans of the streambanks were collected from a canoe using motion-compensated, real-time positioning solutions. Initial geomorphic surveys were used as a baseline to which subsequent repeat surveys were compared using geomorphic change detection analysis. Detectable elevation changes were determined using statistically robust thresholds, ensuring only changes exceeding measurement uncertainty were considered for interpretive analyses. Change detection results identified that 16.4 percent of the reach experienced detectable geomorphic change during the study period, with inter-survey changes ranging from 3.5 to 12.4 percent of the total reach. Most detectable change is attributed to the installation and reconfiguration of temporary construction pads; other changes are attributed to enlargement of a scour hole and upstream deposition near the bridge. Although anthropogenic activities and changes in streamflow regime contributed to these observations, the approach used in this study provides confidence that reported values reflect real geomorphic changes and not noise.

North Carolina↗
USGS2001

General field and office procedures for indirect discharge measurements

The discharge of streams is usually measured by the current-meter method. During flood periods, however, it is frequently impossible or impractical to measure the discharges by this method when they occur. Consequently, many peak discharges must be determined after the passage of the flood by indirect methods, such as slope-area, contracted-opening, flow-over-dam, and flow-through-culvert, rather than by direct current-meter measurement. Indirect methods of determining peak discharge are based on hydraulic equations which relate the discharge to the water-surface profile and the geometry of the channel. A field survey is made after the flood to determine the location and elevation of high-water marks and the characteristics of the channel. Detailed descriptions of the general procedures used in collecting the field data and in computing the discharge are given in this report. Each of the methods requires special procedures described in subsequent chapters.

Techniques of Water-Resources Investigations↗
USGS2001

Steady-state flow distribution and monthly flow duration in selected branches of St. Clair and Detroit rivers within the Great Lakes waterway

St. Clair and Detroit Rivers are connecting channels between Lake Huron and Lake Erie in the Great Lakes waterway, and form part of the boundary between the United States and Canada. St. Clair River, the upper connecting channel, drains 222,400 square miles and has an average flow of about 182,000 cubic feet per second. Water from St. Clair River combines with local inflows and discharges into Lake St. Clair before flowing into Detroit River. In some reaches of St. Clair and Detroit Rivers, islands and dikes split the flow into two to four branches. Even when the flow in a reach is known, proportions of flows within individual branches of a reach are uncertain. Simple linear regression equations, subject to a flow continuity constraint, are developed to provide estimators of these proportions and flows. The equations are based on 533 paired measurements of flow in 13 reaches forming 31 branches. The equations provide a means for computing the expected values and uncertainties of steady-state flows on the basis of flow conditions specified at the upstream boundaries of the waterway. In 7 upstream reaches, flow is considered fixed because it can be determined on the basis of flows specified at waterway boundaries and flow continuity. In these reaches, the uncertainties of flow proportions indicated by the regression equations can be used directly to determine the uncertainties of the corresponding flows. In the remaining 6 downstream reaches, flow is considered uncertain because these reaches do not receive flow from all the branches of an upstream reach, or they receive flow from some branches of more than one upstream reach. Monte Carlo simulation analysis is used to quantify this increase in uncertainty associated with the propagation of uncertainties from upstream reaches to downstream reaches. To eliminate the need for Monte Carlo simulations for routine calculations, polynomial regression equations are developed to approximate the variation in uncertainties as a function of flow at the headwaters of St. Clair River. Finally, monthly flow-duration data on the main channels of St. Clair and Detroit Rivers are used with the equations developed in this report to estimate the steady-state flow-duration characteristics of selected branches.

Detroit River, St. Clair River↗
USGS2001

Ground-water discharge determined from estimates of evapotranspiration, Death Valley regional flow system, Nevada and California

The Death Valley regional flow system (DVRFS) is one of the larger ground-water flow systems in the southwestern United States and includes much of southern Nevada and the Death Valley region of eastern California. Centrally located within the ground-water flow system is the Nevada Test Site (NTS). The NTS, a large tract covering about 1,375 square miles, historically has been used for testing nuclear devices and currently is being studied as a potential repository for the long-term storage of high-level nuclear waste generated in the United States. The U.S. Department of Energy, as mandated by Federal and State regulators, is evaluating the risk associated with contaminants that have been or may be introduced into the subsurface as a consequence of any past or future activities at the NTS. Because subsurface contaminants can be transported away from the NTS by ground water, components of the ground-water budget are of great interest. One such component is regional ground-water discharge. Most of the ground water leaving the DVRFS is limited to local areas where geologic and hydrologic conditions force ground water upward toward the surface to discharge at springs and seeps. Available estimates of ground-water discharge are based primarily on early work done as part of regional reconnaissance studies. These early efforts covered large, geologically complex areas and often applied substantially different techniques to estimate ground-water discharge. This report describes the results of a study that provides more consistent, accurate, and scientifically defensible measures of regional ground-water losses from each of the major discharge areas of the DVRFS. Estimates of ground-water discharge presented in this report are based on a rigorous quantification of local evapotranspiration (ET). The study identifies areas of ongoing ground-water ET, delineates different ET areas based on similarities in vegetation and soil-moisture conditions, and determines an ET rate for each delineated area. Each area, referred to as an ET unit, generally consists of one or more assemblages of local phreatophytes or a unique moist soil environment. Ten ET units are identified throughout the DVRFS based on differences in spectral-reflectance characteristics. Spectral differences are determined from satellite imagery acquired June 21, 1989, and June 13, 1992. The units identified include areas of open playa, moist bare soils, sparse to dense vegetation, and open water. ET rates estimated for each ET unit range from a few tenths of a foot per year for open playa to nearly 9 feet per year for open water. Mean annual ET estimates are computed for each discharge area by summing estimates of annual ET from each ET unit within a discharge area. The estimate of annual ET from each ET unit is computed as the product of an ET unit's acreage and estimated ET rate. Estimates of mean annual ET range from 450 acre-feet in the Franklin Well area to 30,000 acre-feet in Sarcobatus Flat. Ground-water discharge is estimated as annual ET minus that part of ET attributed to local precipitation. Mean annual ground-water discharge estimates range from 350 acre-feet in the Franklin Well area to 18,000 acre-feet in Ash Meadows. Generally, these estimates are greater for the northern discharge areas (Sarcobatus Flat and Oasis Valley) and less for the southern discharge areas (Franklin Lake, Shoshone area, and Tecopa/ California Valley area) than those previously reported.

California, Nevada↗
USGS2003

Estimating the magnitude of peak flows for streams in Kentucky for selected recurrence intervals

This report gives estimates of, and presents techniques for estimating, the magnitude of peak flows for streams in Kentucky for recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years. A flowchart in this report guides the user to the appropriate estimates and (or) estimating techniques for a site on a specific stream. Estimates of peak flows are given for 222 U.S. Geological Survey streamflow-gaging stations in Kentucky. In the development of the peak-flow estimates at gaging stations, a new generalized skew coefficient was calculated for the State. This single statewide value of 0.011 (with a standard error of prediction of 0.520) is more appropriate for Kentucky than the national skew isoline map in Bulletin 17B of the Interagency Advisory Committee on Water Data. Regression equations are presented for estimating the peak flows on ungaged, unregulated streams in rural drainage basins. The equations were developed by use of generalized-least-squares regression procedures at 187 U.S. Geological Survey gaging stations in Kentucky and 51 stations in surrounding States. Kentucky was divided into seven flood regions. Total drainage area is used in the final regression equations as the sole explanatory variable, except in Regions 1 and 4 where main-channel slope also was used. The smallest average standard errors of prediction were in Region 3 (from -13.1 to +15.0 percent) and the largest average standard errors of prediction were in Region 5 (from -37.6 to +60.3 percent). One section of this report describes techniques for estimating peak flows for ungaged sites on gaged, unregulated streams in rural drainage basins. Another section references two previous U.S. Geological Survey reports for peak-flow estimates on ungaged, unregulated, urban streams. Estimating peak flows at ungaged sites on regulated streams is beyond the scope of this report, because peak flows on regulated streams are dependent upon variable human activities.

Kentucky↗
USGS1979

River mileages and drainage areas for Illinois streams—Volume 1, Illinois except Illinois River basin

River mileages are presented for points of interest on Illinois streams draining 10 square miles or more. Points of interest include bridges, dams, gaging stations, county lines, hydrologic unit boundaries, and major tributaries. Drainage areas are presented for selected sites, including total drainage area for any stream draining at least 100 square miles. The report is contained in two volumes. This volume (Volume I) includes Illinois except Illinois River basin.

Illinois↗
USGS1984

Maps to estimate average streamflow and headwater limits for streams in U.S. Army Corps of Engineers, Mobile District, Alabama and adjacent states

U.S. Army Corps of Engineers permits are required for discharges of dredged or fill-material downstream from the ' headwaters ' of specified streams. The term ' headwaters ' is defined as the point of a freshwater (non-tidal) stream above which the average flow is less than 5 cu ft/s. Maps of the Mobile District area showing (1) lines of equal average streamflow, and (2) lines of equal drainage areas required to produce an average flow of 5 cu ft/s are contained in this report. These maps are for use by the Corps of Engineers in their permitting program. (USGS)

Water-Resources Investigations Report↗
USGS1991

Bibliography of Regional Aquifer-System Analysis Program of the US Geological Survey, 1978-91

The Regional Aquifer-System Analysis (RASA) Program of the U.S. Geological Survey was initiated in 1978. The purpose of this program is to define the regional geohydrology and establish a framework of background information on geology, hydrology, and geochemistry of the Nation's important aquifer systems. This information is critically needed to develop an understanding of the Nation's major ground-water flow systems and to support better management of ground-water resources. As of May 1991, 28 of the Nation's major aquifer systems have been identified for study under this program. Of these, 17 regional aquifer-system studies have been completed, and 8 studies are ongoing. Starting in 1988, the program devoted part of its resources to compilation of a Nationwide ground-water atlas that presents a comprehensive summary of the Nation's major ground-water resources. The atlas, which is designed in a graphical format supported by descriptive text, will serve as a basic reference for the location, geography, geology, and hydrologic characteristics of the major aquifers in the Nation. This bibliography lists the published 876 reports resulting from various studies of the program, from 1978 through May 1991. The list of reports for each study is placed after a brief description of that study.

Water-Resources Investigations Report↗
USGS1996

Magnitude and frequency of floods in Alabama

Methods of estimating flood magnitudes for recurrence intervals of 2, 5, 10, 25, 50,100, 200, and 500 years are described for rural streams in Alabama that are not affected by regulation or urbanization. Flood-frequency characteristics are presented for 198 gaging stations in Alabama having 10 or more years of record through September 1991, that are used in the regional analysis. Regression relations were developed using generalized least-squares regression techniques to estimate flood magnitude and frequency on ungaged streams as a function of the drainage area of a basin. Sites on gaged streams should be weighted with gaging station data that are presented in the report Graphical relations of peak discharges to drainage areas are also presented for siter along the Alabama, Black Warrior, Cahaba, Choctawhatchee, Conecuh, and Tombigbee Rivers. Equations for estimating flood magnitudes on ungaged urban streams (taken from a previous report) that use drainage area and percentage of impervious cover as independent variables also are given.

Alabama↗