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At least 1,315 records · Page 73Linked to original sources
USGS2022

Water-quality trends in surface waters of the Jemez River and Middle Rio Grande Basin from Cochiti to Albuquerque, New Mexico, 2004–19

Municipal water supply for Albuquerque, New Mexico, is provided, in part, through diversion of surface water from the Rio Grande by way of the San Juan-Chama Drinking Water Project diversion structure. Changes in surface-water quality along the Rio Grande and its tributaries upstream from the San Juan-Chama Drinking Water Project diversion structure are not well characterized. This study describes the methods and results of an analysis of surface-water-quality trends for selected constituents in the Rio Grande upstream from Albuquerque. Trends were evaluated for differing time periods ranging from 2004 to 2019 by using the Seasonal Kendall Tau (SKT) test and the Weighted Regressions on Time, Discharge, and Season (WRTDS) model. Water-quality data at three long-term sites were used for the trend analyses in this study, with the Cochiti and Alameda sites along the Rio Grande and the Jemez Canyon Dam site along the Jemez River, a tributary of the Rio Grande. The proximity of the Cochiti and Jemez Canyon Dam sites to dams is a drawback to the analysis because it is difficult to differentiate between the influence of dam management and the influence of streamflow on water-quality trends. The data used also did not fully meet desired levels of seasonal sampling density and had shorter periods of record than typically used for trend analysis, and this should be considered in the interpretation of these results. Study results indicate that concentrations, and thereby fluxes, are influenced by changes in streamflow at the Alameda site. Most trends from the WRTDS results, obtained by using flow-normalization, were downward for constituents at the Alameda site. Most constituents that were analyzed for trends by using SKT did not have a significant trend at any of the sites included in this study, indicating either that the water quality in the Middle Rio Grande Basin has been stable during the study period or that not enough samples were collected during different seasons to characterize the range of concentration variability with streamflow. The SKT test results indicate upward trends in concentrations of the following constituents: aluminum and antimony at the Alameda site, nitrate and nitrate plus nitrite at the Cochiti site, and potassium and antimony during the spring season at Jemez Canyon Dam. The SKT test results indicate a downward trend in cobalt at the Cochiti site that is subject to bias in the cobalt concentrations. SKT test results also indicate small, downward trends in Kjeldahl nitrogen at the Alameda and Cochiti sites. Concentrations of water-quality constituents were also compared to Federal and State water-quality standards to provide context and relevance to the results. No concentrations were above the national primary or secondary drinking water standards at the Alameda and Cochiti sites, but the Jemez Canyon Dam site did have concentrations above the U.S. Environmental Protection Agency primary drinking water standard for arsenic and above the national secondary drinking water standards for dissolved solids and aluminum. The Alameda and Cochiti sites are on reaches of the Rio Grande that are listed as impaired for gross alpha particles and the Alameda site is on a reach of the Rio Grande that is listed as impaired for Escherichia coli , but there were no consistent changes in concentrations of these constituents at the impaired locations.

New Mexico↗
USGS2025

Fluvial sediment dynamics in the Shoshone River and tributaries around Willwood Dam, Park County, Wyoming

Sedimentation affects many of the aging reservoirs in the United States. Dams and water diversions from rivers have been central elements of infrastructure supporting agricultural irrigation in the arid and semiarid regions of the Western United States for more than a century. The Willwood Irrigation District diversion dam (hereafter referred to as “Willwood Dam”) in Park County, Wyoming, is approximately 12 miles northeast of Cody, Wyo.; has a structural height of 70 feet; and impounds the Shoshone River for diversion into the Willwood Canal. Willwood Dam is part of a larger irrigation scheme supported by water storage in the much larger Buffalo Bill Dam, which is approximately 20 miles upstream. In October 2016, renovation construction activities at Willwood Dam and the Willwood Canal caused an unplanned evacuation of nearly 96,000 cubic yards of fine sediment. The fine sediment release in 2016 raised concerns that ongoing sediment management at Willwood Dam could impose limits on the long-term health of the aquatic ecosystem and fish populations. The U.S. Geological Survey, in cooperation with Wyoming Department of Environmental Quality and Willwood Work Groups 2 and 3, initiated an investigation of the dynamics of sediment transport in the Shoshone River and selected tributaries between Buffalo Bill Dam and Willwood Dam. The goal of the study was to quantify sediment transport into and out of Willwood Dam on an annual, seasonal, and event basis to better understand the relative quantities of sediment coming from natural sources and human activities on the landscape. The study ran from March 2019 through October 2021 and used observations of streamflow, turbidity, and acoustic backscatter collected at streamgages upstream and downstream from Willwood Dam to quantify suspended-sediment loads into and out of the dam during irrigation and fallow seasons, precipitation-runoff events, and deliberate sediment releases. Each tributary’s relative contribution to the sediment load upstream from Willwood Dam was examined using discrete measurements of suspended-sediment concentration and bedload during irrigation and fallow seasons, precipitation events, and stable conditions. Analysis of daily precipitation and temperature data indicated that conditions in the study area during the 2019 agricultural year were wetter and colder than period of record normal, and drier and near normal temperatures for the 2020 and 2021 agricultural years. Not all sediment load records between 2019 and 2021 are complete because of rejected observations (outliers), instrument failures or fouling, and instrument removal for calibrations. Statistical modeling of suspended-sediment concentration using paired values of turbidity and acoustic backscatter produced four models that, after refinement, had coefficients of determination indicating that more than 84 percent of the variance was explained by either turbidity or acoustic backscatter. A system of rules was developed to select the model predictions based on the seasonal operations of Willwood Dam, assumptions about the grain sizes mobilized during these operations, and assumed accuracy of the models at the downstream streamgage (Shoshone River below Willwood Dam, near Ralston, Wyo. [streamgage 06284010]) under different operational conditions. The sediment budget between upstream and downstream estimates of loads was interpreted using the mean predicted values bound by their respective model prediction intervals. When mean predicted loads of one streamgage were contained in the prediction intervals of the other streamgage, and vice-versa, difference in the sediment budget were interpreted as “indeterminate.” Modeled sediment load balances demonstrated the depositional and erosional behaviors expected from the conceptual model of dam operations whereby sediment tends to accumulate during irrigation seasons when the dam is spilling over the top, and sediment tends to evacuate during the fallow seasons when it is flowing through the sluice gates at the base of the dam. The sediment load calculations using the rules-based model criteria indicated that between 14,200 and 380,000 tons of suspended sediment moved through the Shoshone River around Willwood Dam during the irrigation seasons of 2019, 2020, and 2021; 380,000 tons of suspended sediment were transported during the cool, wet year of 2019, and 14,200 tons of suspended sediment were transported in 2020, which was relatively dry. During fallow seasons 2019, 2020, and 2021, which had fewer complete records, between 1,140 and 106,000 tons of suspended sediment was estimated to have moved through the river. For all seasons except fallow season 2022, the models estimated that more sediment was released from the dam than entered the dam, but the modeled mean loads at each streamgage were nearly always within the prediction intervals of each other, making the sediment balance indeterminant. Examination of suspended-sediment loads during irrigation seasons indicated that between 65 and 85 percent of fine sediment was transported during annual high flows and storm events, with the remainder transported during steady, lower streamflows. Examination of suspended loads during fallow seasons indicated that deliberate sediment releases through Willwood Dam accounted for between 39 and 67 percent of the total sediment moved during the fallow seasons. Deliberate sediment releases from Willwood Dam had estimated net exports of between 1,360 and 22,400 tons. Between August 2017 and July 2023, suspended-sediment concentration and bedload sediment samples were collected from 9 tributaries to the Shoshone River during 137 sampling events, including stable and precipitation-runoff conditions. During irrigation season precipitation events, the mean total sediment yields ranged from 0.33 to 9.51 tons per day per square mile; during fallow season precipitation events, the mean total yields ranged from 0.04 to 0.95 ton per day per square mile. The mean total sediment yield per unit area across all samples at each tributary site ranged from 0.26 to 3.08 tons per day per square mile. Bedload was a minor fraction of the total load, constituting a mean of 4 percent across all samples; 3 and 6 percent for events and nonevents, respectively, during irrigation season; and 3 and 1 percent for events and nonevents, respectively, during the fallow season. With the exception of one tributary, Dry Creek, these mean yield values were within the range of watershed-scale background sediment yield values estimated from reservoir surveys and previous suspended-sediment studies. Imagery from irrigation seasons 2012, 2015, 2017, 2019, and 2022 was used to determine the planimetric backwater extent of the pool area in the Shoshone River behind Willwood Dam to identify any changes in sediment storage. Active river channel widths in the Shoshone River upstream from Willwood Dam were all similar between years except 2015, which was determined to be statistically different from all other years. Bathymetric data taken in the pool behind Willwood Dam during three different surveys between November 2017 and April 2022 indicated no statistically significant differences in bed elevations between the years. Results from the planimetric and bathymetric survey data provide multiple lines of evidence indicating that sediment did not accumulate behind the dam within the error of the methods used. Examination of how precipitation affects sediment transport in the Shoshone River upstream from Willwood Dam indicated that accumulated rainfall from the natural runoff events captured during the study period varied from a trace to as much as 4.26 inches, with associated predicted suspended-sediment loads varying from 112 to 232,000 tons of suspended sediment. The behavior of the sediment loads relative to accumulated precipitation did not appear to change depending on irrigation or fallow season. A model of suspended-sediment concentrations relative to the 2-day accumulated precipitation indicated that suspended-sediment concentrations in the Shoshone River upstream from Willwood Dam increased exponentially for accumulations of 0.3 inch or more; such storms accounted for 10 percent or less of precipitation events observed during the 1981 to 2018 period of record. The gaps in records, precision of the instrumentation, and large variation in grain sizes in suspended-sediment mixtures downstream from the dam made closing the sediment budgets for most seasons unattainable. The biggest recent change in sediment storage measured using the planimetric area of deposits behind Willwood Dam took place between 2015 and 2017. The main event between these two measurements was the installation of new Willwood Canal gates in October 2016, which resulted in the large unplanned sediment release. Because the sediment budgets were nearly always indeterminate and the planimetric and bathymetric data indicated little change in the bed and bank material, it is likely that the change in sediment storage behind the dam during the study period was small relative to the precision of the statistical models and other uncertainties. This body of evidence suggests that, averaged during the 3-year study period, no major changes in storage took place, and that the current operations may be keeping storage at near-equilibrium. This condition could have been initiated because the middle sluice gate has now been operational since 2014, and the sediment release in October 2016 evacuated a large amount of legacy sediment from storage. Although the uncertainties are large, sluicing events allow for controlled releases of sediment that contributed to the near equilibrium conditions observed over an annual basis during this study.

Wyoming↗
USGS2026

Water-budget simulations for selected watersheds in Cameron County, Texas, 2022–23

The U.S. Geological Survey, in cooperation with the City of Brownsville, Texas, configured and calibrated a set of hydrologic models for a 217-square-mile study area in Cameron County in south Texas during 2022–23. The models were used for estimating runoff and quantities of water diverted from the Rio Grande/Rio Bravo del Norte (hereinafter referred to as the “Rio Grande”) to maintain water-surface elevations in the canals and resacas (former distributary channels cut off from the main channel of the Rio Grande). Resacas provide habitat to aquatic species and help reduce the effects of flooding. Because of the large size of the study area and diversity of hydrologic conditions, the study area was divided into 11 watersheds, and separate hydrologic models were developed for 9 of the watersheds. Six of the nine modeled watersheds are drained mostly by canals (canal watersheds), and three of the modeled watersheds drain to resacas (resaca watersheds). The Hydrological Simulation Program—FORTRAN was selected for modeling the study area watersheds because it is flexible in simulating a wide variety of watershed conditions. The models were calibrated with streamflow data collected during 2022–23. The calibrated models were used to simulate water budgets (streamflow, evapotranspiration, water-storage volumes, and water diversions and withdrawals) during 2022–23. Model simulations showed that the resaca watersheds required more diversions from the Rio Grande and released less runoff than did the canal watersheds. Management practices maintaining resaca water levels constrained their runoff.

Texas↗
USGS2011

User's manual for the National Water-Quality Assessment Program Invertebrate Data Analysis System (IDAS) software, version 5

The Invertebrate Data Analysis System (IDAS) software was developed to provide an accurate, consistent, and efficient mechanism for analyzing invertebrate data collected as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. The IDAS software is a stand-alone program for personal computers that run Microsoft Windows(Registered). It allows users to read data downloaded from the NAWQA Program Biological Transactional Database (Bio-TDB) or to import data from other sources either as Microsoft Excel(Registered) or Microsoft Access(Registered) files. The program consists of five modules: Edit Data, Data Preparation, Calculate Community Metrics, Calculate Diversities and Similarities, and Data Export. The Edit Data module allows the user to subset data on the basis of taxonomy or sample type, extract a random subsample of data, combine or delete data, summarize distributions, resolve ambiguous taxa (see glossary) and conditional/provisional taxa, import non-NAWQA data, and maintain and create files of invertebrate attributes that are used in the calculation of invertebrate metrics. The Data Preparation module allows the user to select the type(s) of sample(s) to process, calculate densities, delete taxa on the basis of laboratory processing notes, delete pupae or terrestrial adults, combine lifestages or keep them separate, select a lowest taxonomic level for analysis, delete rare taxa on the basis of the number of sites where a taxon occurs and (or) the abundance of a taxon in a sample, and resolve taxonomic ambiguities by one of four methods. The Calculate Community Metrics module allows the user to calculate 184 community metrics, including metrics based on organism tolerances, functional feeding groups, and behavior. The Calculate Diversities and Similarities module allows the user to calculate nine diversity and eight similarity indices. The Data Export module allows the user to export data to other software packages (CANOCO, Primer, PC-ORD, MVSP) and produce tables of community data that can be imported into spreadsheet, database, graphics, statistics, and word-processing programs. The IDAS program facilitates the documentation of analyses by keeping a log of the data that are processed, the files that are generated, and the program settings used to process the data. Though the IDAS program was developed to process NAWQA Program invertebrate data downloaded from Bio-TDB, the Edit Data module includes tools that can be used to convert non-NAWQA data into Bio-TDB format. Consequently, the data manipulation, analysis, and export procedures provided by the IDAS program can be used to process data generated outside of the NAWQA Program.

Techniques and Methods↗
USGS2001

Use of a precipitation-runoff model to simulate natural streamflow conditions in the Methow River basin, Washington

Management of the water resources of the Methow River Basin is changing in response to the listing of three species of fish under the Endangered Species Act and the Washington State-legislated watershed-planning process. Management options must be considered that minimize adverse effects on people but meet instream flow needs for fish. This report describes the construction and calibration of the Methow River Basin watershed model and evaluates the accuracy of the model as a predictive tool for assessing the natural instream flow conditions. The term ?natural? instream flow is stressed because surface water within the Basin is used for agricultural irrigation through an extensive system of diversions. The USGS Modular Modeling System was used for the watershed modeling component of the Methow River Basin study. The Geographic Information System Weasel characterized the physical properties of the basin, and the Precipitation-Runoff Modeling System simulated the natural streamflow. Natural streamflow conditions in the Basin were difficult to calibrate because six of the seven streamflow gaging stations are located below irrigation diversions and few streamflow measurements exist for the study area before the diversions were present. Therefore, limited records of natural streamflow conditions were available and estimations concerning some physical processes could not be quantified. Streamflow was simulated for water years 1992-99 to calibrate the model to measured streamflows. Simulated and measured streamflow generally showed close agreement, especially during spring runoff from snowmelt. Low-flow periods, most restrictive to fish habitation, were simulated reasonably well, yet possessed the most uncertainty. Simulations of the total annual runoff as a percentage of measured annual runoff for the 8-year calibration period at seven gaging stations ranged from -33.7 to +30.5 percent with 70 percent of the simulated values within 16 percent. Simulation of water years 1959-99 demonstrated great variability in monthly streamflow statistics. The simulated mean monthly flows for the seven streamflow-gaging stations were an average of 11.5 percent higher for the calibration period (1992-99) than for the entire simulation period (1959-99).

Water-Resources Investigations Report↗
USGS2006

Comprehensive water quality of the Boulder Creek Watershed, Colorado, during high-flow and low-flow conditions, 2000

Executive Summary The Boulder Creek Watershed, Colorado, is 1160 square kilometers in area and ranges in elevation from 1480 to 4120 meters above sea level. Streamflow originates primarily as snowmelt near the Continental Divide, and thus discharge varies seasonally and annually (Chapter 1). Most of the water in Boulder Creek is diverted for domestic, agricultural, and industrial use. Some diverted water is returned to the creek as wastewater effluent and by ditch returns, and additional water enters as groundwater and by transbasin diversions. These diversions and returns lead to complex temporal and spatial variations in discharge. The variations in discharge, along with natural factors such as geology and climate, and anthropogenic factors such as wastewater treatment, agriculture, mining, and urbanization, can affect water chemistry. As with many watersheds in the American West, dependable water quality and sufficient water supply are issues facing local water managers and users. Detailed water-quality and sediment sampling allows the identification of sources and sinks of chemical constituents and an understanding of the processes at work in a river system. This study, the most comprehensive water-quality analysis performed for Boulder Creek to date, was a cooperative effort of the U.S. Geological Survey (USGS) and the city of Boulder. Geographic information systems and modeling programs were used to delineate watershed boundaries, land cover, and geology (Chapter 2). During high-flow (June 2000) and low-flow (October 2000) conditions, researchers evaluated 226 water-quality variables, including basic water-quality indicators (Chapter 3), major ions and trace elements (Chapter 4), wastewater-derived organic compounds (Chapter 5), and pesticides (Chapter 6). Discharge (Chapter 1) and bed-sediment particle size and mineralogy (Chapter 7) were also evaluated. This cooperative study was facilitated by the Boulder Area Sustainability Information Network (BASIN), which provides public access to environmental information about the Boulder Creek Watershed on a website, www.basin.org. In addition to the USGS and city of Boulder data, researchers at the Institute of Arctic and Alpine Research at the University of Colorado provided water chemistry data for the headwaters of North Boulder Creek, upstream of the reach of the USGS/city of Boulder sampling sites (Chapter 8). Snowmelt produces high flows in Boulder Creek in late spring to early summer (Chapter 1). Because precipitation falling in the headwaters is very dilute (specific conductance about 5 microsiemens per centimeter), most chemical constituents are present in lower concentrations during high flows (Chapters 3, 4, 5, 6, and 8). However, concentrations of some constituents, such as total suspended solids (Chapter 3) and organic carbon (Chapter 5), increase during the spring snowmelt flush. The upper basin, which consists of alpine, subalpine, montane, and foothills regions west of the mouth of Boulder Canyon, is underlain by Precambrian igneous and metamorphic rocks (Chapter 1). Major dissolved inorganic constituents in headwater sites were found to be enriched by factors of 10 to 20 relative to precipitation; this is consistent with minor weathering of the local crystalline bedrock (Chapter 4). Some anthropogenic input is observed in the headwaters; precipitation introduces nitrogen derived from fossil fuel combustion and agricultural activities (Chapter 8). The lower basin, which consists of the plains region east of the mouth of Boulder Canyon, is underlain by Mesozoic sedimentary rock and Quaternary alluvium, and has substantially more anthropogenic sources. Concentrations of most dissolved inorganic constituents increased in the lower basin. Differentiation between natural and anthropogenic sources of some dissolved constituents is difficult because both sources contribute to the water composition in this region. The increase of most major constituents (bicarbonate, calcium, chloride, magnesium, sodium, and sulfate) is consistent with weathering of the underlying sedimentary bedrock (Chapter 4). It is likely that anthropogenic loading of constituents in this reach occurs during storm events. Fecal coliform concentrations were variable and in some cases exceeded state standards, primarily during low-flow conditions (Chapter 3). Effluent from Boulder’s 75th Street Wastewater Treatment Plant (WWTP) has a substantial impact on the water chemistry of lower Boulder Creek. The WWTP increases the concentrations of nutrients such as nitrogen and phosphorus (Chapter 3), major ions and trace metals (Chapter 4), and organic carbon (Chapter 5) in Boulder Creek. The effluent contained a spike in gadolinium, a rare earth element that is ingested for magnetic resonance imaging as a contrasting agent and then excreted to the urban wastewater system. The effluent also contained trace organic compounds such as surfactants, pharmaceuticals, hormones (Chapter 5), and pesticides (Chapter 6), which also were detected at downstream Boulder Creek sites. Water chemistry of Boulder Creek downstream of the WWTP is largely controlled by the degree of dilution of the wastewater effluent, which varies depending on the baseflow of Boulder Creek, the volume of wastewater effluent, and depletion by agricultural diversions. Coal Creek, a tributary of Boulder Creek, contains wastewater effluent from four additional WWTPs, and increases the load of many constituents in Boulder Creek. In addition to the impact from wastewater effluent, lower Boulder Creek is affected by agricultural land use. Eleven of 84 analyzed pesticides were detected in Boulder Creek or its inflows, primarily in the eastern section of the watershed (Chapter 6). This collaborative study provides an in-depth evaluation of the hydrology, water chemistry, and sediment mineralogy of North Boulder Creek, Middle Boulder Creek, Boulder Creek, and major inflows. The detailed sampling and analysis in this report provide a baseline for future reference, as well as information on the effect of land use and geology on water chemistry.

Colorado↗
USGS2003

Patterns and sources of fecal coliform bacteria in three streams in Virginia, 1999-2000

Surface-water impairment by fecal coliform bacteria is a water-quality issue of national scope and importance. In Virginia, more than 175 stream segments are on the Commonwealth's 1998 303(d) list of impaired waters because of elevated concentrations of fecal coliform bacteria. These fecal coliform-impaired stream segments require the development of total maximum daily load (TMDL) and associated implementation plans, but accurate information on the sources contributing these bacteria usually is lacking. The development of defendable fecal coliform TMDLs and management plans can benefit from reliable information on the bacteria sources that are responsible for the impairment. Bacterial source tracking (BST) recently has emerged as a powerful tool for identifying the sources of fecal coliform bacteria that impair surface waters. In a demonstration of BST technology, three watersheds on Virginia's 1998 303(d) list with diverse land-use practices (and potentially diverse bacteria sources) were studied. Accotink Creek is dominated by urban land uses, Christians Creek by agricultural land uses, and Blacks Run is affected by both urban and agricultural land uses. During the 20-month field study (March 1999?October 2000), water samples were collected from each stream during a range of flow conditions and seasons. For each sample, specific conductance, dissolved oxygen concentration, pH, turbidity, flow, and water temperature were measured. Fecal coliform concentrations of each water sample were determined using the membrane filtration technique. Next, Escherichia coli (E. coli) were isolated from the fecal coliform bacteria and their sources were identified using ribotyping (a method of 'genetic fingerprinting'). Study results provide enhanced understanding of the concentrations and sources of fecal coliform bacteria in these three watersheds. Continuum sampling (sampling along the length of the streams) indicated that elevated concentrations of fecal coliform bacteria (maximum observed concentration of 290,000 colonies/100 milliliters (col/100mL) could occur along the entire length of each stream, and that the samples collected at the downstream monitoring station of each stream were generally representative of the entire upstream reach. Seasonal patterns were observed in the base-flow fecal coliform concentrations of all streams; concentrations were typically highest in the summer and lowest in the winter. Fecal coliform concentrations were lowest during periods of base flow (typically 200?2,000 col/100mL) and increased by 3?4 orders of magnitude during storm events (as high as 700,000 col/100mL). Multiple linear regression models were developed to predict fecal coliform concentrations as a function of streamflow and other water-quality parameters. The source tracking technique provided identification of bacteria contributions from diverse sources that included (but were not limited to) humans, cattle, poultry, horses, dogs, cats, geese, ducks, raccoons, and deer. Seasonal patterns were observed in the contributions of cattle and poultry sources. There were relations between the identified sources of fecal coliform bacteria and the land-use practices within each watershed. There were only minor differences in the distribution of bacteria sources between low-flow periods and high-flow periods. A coupled approach that utilized both a large available source library and a smaller, location-specific source library provided the most success in identifying the unknown E. coli isolates. BST data should provide valuable support and guidance for producing more defendable and scientifically rigorous watershed models. Incorporation of these bacteria-source data into watershed management strategies also should result in the selection of more efficient source-reduction scenarios for improving water quality.

Water-Resources Investigations Report↗
USGS2003

Conjunctive-use optimization model of the Mississippi River Valley alluvial aquifer of northeastern Arkansas

The Mississippi River Valley alluvial aquifer is a water-bearing assemblage of gravels and sands that underlies about 32,000 square miles of Missouri, Kentucky, Tennessee, Mississippi, Louisiana, and Arkansas. Because of the heavy demands placed on the aquifer, several large cones of depression over 100 feet deep have formed in the potentiometric surface, resulting in lower well yields and degraded water quality in some areas. A ground-water flow model of the alluvial aquifer was previously developed for an area covering 14,104 square miles, extending northeast from the Arkansas River into the northeast corner of Arkansas and parts of southeastern Missouri. The flow model showed that continued ground-water withdrawals at rates commensurate with those of 1997 could not be sustained indefinitely without causing water levels to decline below half the original saturated thickness of the aquifer. To develop estimates of withdrawal rates that could be sustained in compliance with the constraints of critical ground-water area designation, conjunctive-use optimization modeling was applied to the flow model of the alluvial aquifer in northeastern Arkansas. Ground-water withdrawal rates form the basis for estimates of sustainable yield from the alluvial aquifer and from rivers specified within the alluvial aquifer model. A management problem was formulated as one of maximizing the sustainable yield from all ground-water and surface-water withdrawal cells within limits imposed by plausible withdrawal rates, and within specified constraints involving hydraulic head and streamflow. Steady-state flow conditions were selected because the maximized withdrawals are intended to represent sustainable yield of the system (a rate that can be maintained indefinitely). Within the optimization model, 11 rivers are specified. Surface-water diversion rates that occurred in 2000 were subtracted from specified overland flow at the appropriate river cells. Included in these diversions were the planned diversions of 63,339,248 ft3/d for the Bayou Meto project area and 55,078,367 ft3/d for the Grand Prairie project area, which factor in an additional 30 and 40 percent transmission loss, respectively. Streamflow constraints were specified at all 1,165 river cells based on average 7-day minimum flows for 10 years. Sustainable yield for all rivers ranged from 0 (Current, Little Red, and Bayou Meto Rivers) to almost 5 billion cubic feet per day for the Arkansas River. Total sustainable yield from all rivers combined was 12.8 billion cubic feet per day, which represents a substantial source for supplementing ground water to meet the total water demand. Sustainable-yield estimates are affected by the allowable upper limit on withdrawals from wells specified in the optimization model. Ground-water withdrawal rates were allowed to vary as much as 200 percent of the withdrawal rate in 1997. As the overall upper limit on withdrawals is increased, the sustainable yield generally increases. Tests with the optimization model show that without limits on pumping, wells adjacent to sources of water would have optimized withdrawal rates that were orders of magnitude larger than rates corresponding to those of 1997. The sustainable yield from ground water for the entire study area while setting the maximum upper limit as the amount withdrawn in 1997 is 360 million cubic feet per day, which is only about 57 percent of the amount withdrawn in 1997 (635.6 million cubic feet per day). Optimal sustainable yields from within the Bayou Meto irrigation project area and within the Grand Prairie irrigation project area are 18.1 and 9.1 million cubic feet per day, respectively, assuming a maximum allowable withdrawal rate equal to 1997 rates. These values of sustainable yield represent 35 and 30 percent respectively of the amount pumped from these project areas in 1997. Unmet demand (defined as the difference between the optimized withdrawal rate or sustainable yield, and the anticipated demand) was calculated using different demand rates based on multiples of the 1997 withdrawal rate. Assuming that demand is the 1997 withdrawal rate, and that sustainable-yield estimates are those obtained using upper limits of withdrawal rates of 100-, 150-, and 200-percent of 1997 withdrawal rates, then the resulting unmet demand for the entire model area is 275.5, 190.9, and 110 million cubic feet per day, respectively. Whereas, if the demand is specified as 100-, 150-, and 200-percent of the 1997 withdrawal rate, and the sustainable-yield estimates remain the same, then the resulting unmet demand for the entire model area is 275.5, 508.8, and 745.8 million cubic feet per day, respectively. These unmet demands for ground water could be obtained from large sustainable surface-water withdrawals.

Arkansas↗
USGS1974

Characteristics of streamflow and ground-water conditions in the Boise River Valley, Idaho

The quantity, quality, and distribution in time of streamflow in Boise River below Lucky Peak Lake are drastically affected by storage reservoirs, diversions for irrigation, and by domestic, industrial, and agricultural wastes. Reservoirs usually fill during the nonirrigation season, and streamflow for several miles below Lucky Peak Lake is very low, sometimes less than 10 cubic feet per second (0.28 cubic meters per second). On November 18-19, 1971, when the gates at Lucky Peak Dam were closed, inflow to the Boise River in the study reach totaled 1010 ft 3 /s. Practically all inflow was discharged ground water. During the growing season, several thousands of ft 3 /s are released from Lucky Peak Lake, but diversions reduce the flows to near zero below some large diversion points in the study reach. Characteristics of streamflow are described by duration curves, duration hydrographs, and low-flow and high-flow frequency curves. Water released from Lucky Peak Lake is of excellent quality. Dissolved solids are usually less than 80 milligrams per liter. Discharged ground water increases the dissolved solids in the river downstream to 400 milligrams per liter or more when dilution from Lucky Peak Lake is slight. Other measures of water quality likewise show the deterioration in a downstream direction in the study reach.

Idaho↗
USGS1976

Analysis of selected benthic communities in Florida Everglades with reference to their physical and chemical environment

Species diversity and numbers of benthic macroinvertebrates were determined at 12 sites, both canals and marshes, in the Everglades of south Florida. The values calculated are used to indicate long-term trends in water quality and variations between study areas. Species diversity at all sites was generally in a range indicative of degraded water quality. The number of organisms per square metre of bottom surface was highly variable ranging from 43 to 8,200 organisms. Chemical analysis of water and bottom material indicated no gross contamination from sewage or agricultural runoff in any of the canals where benthic organisms were collected. Other physical factors such as depth, velocity of flow, substrate type, and water-level fluctuation were responsible for the low species diversities and variable numbers of organisms, rather than contamination from urban or agricultural areas.

Florida↗
USGS1977

Artificial recharge experiments on the Ship Creek alluvial fan, Anchorage, Alaska

During the summers of 1973 and 1974, water from Ship Creek was diverted at an average rate of approximately 6 cubic feet per second to an 11-acre recharge basin. Maximum sustained unit recharge for the basin was approximately 1.4 feet per day. Dur-ing 1975 a second basin of 8 acres was also used for recharge, and the total diversion rate was increased to as much as 30 cubic feet per second. The second basin was never completely filled, but the unit recharge rate was estimated to be at least four times as great as that in the first basin. During 1973 and 1974, when only one recharge basin was in operation, a maximum rise of 18 feet was observed in the ground-water table near the basin. In 1975, when both basins were being used, the maximum rise was 30 feet in the same area. During 1973 and 1974, the water-level rise was 12 and 8 feet in the unconfined and confined systems, respectively, at a point 4.400 feet downgradient from the basins; in 1975 the rise at the same point was 31 and 16 feet, respectively. It was originally believed that because of the location of the recharge ponds within the natural recharge zone of the area's confined aquifer system, the source of the major portion of Anchorage's public water supply, most of the artificially recharged water would enter that system. However, water-level data and changes in saturation conditions interpreted from borehole geophysical logs indicate that most of the recharged water remained in the unconfined aquifer. In addition, the potentiometric rise that was achieved in the confined aquifer during summer operation of the recharge basins was quickly dissipated when diversion stopped and the basins drained. Thus the benefits of recharge would not persist into late winter, the critical period of water availability in Anchorage, unless diversion to the basins could be continued until January or February.

Alaska↗
USGS1979

Hydrologic effects of annually diverting 131,000 acre-feet of water from Dillon Reservoir, central Colorado

Because of the increased demands for water in eastern Colorado, principally in the urbanizing Denver metropolitan area, increased diversions of water from Dillon Reservoir are planned. Estimates of end-of-month storage in Dillon Reservoir, assuming the reservoir was in place and 131,000 acre-feet of water were diverted from the reservoir each year, were reconstructed by mass balance for the 1931-77 water years. Based on the analysis, the annual maximum end-of-month drawdown below the elevation at full storage would have averaged 54 feet. The maximum end-of-month drawdown below the elevation at full storage would have been 171 feet. The mean-annual discharge-weighted dissolved-solids concentrations in the Colorado River near Glenwood Springs and Cameo, Colo., and Cisco, Utah, for the 1942-77 water years, were computed assuming an annual diversion of 131,000 acre-feet of water from Dillon Reservoir. The average increases in the dissolved-solids concentrations with the 131 ,000-acre-foot diversion were 15 to 16 milligrams per liter at the three sites. (Woodard-USGS)

Water-Resources Investigations Report↗
USGS1979

Probable hydrologic effects of a hypothetical failure of Mackay Dam on the Big Lost River Valley from Mackay, Idaho to the Idaho National Engineering Laboratory

Mackay Dam is an irrigation reservoir on the Big Lost River, Idaho, approximately 7.2 kilometers northwest of Mackay, Idaho. Consequences of possible rupture of the dam have long concerned the residents of the river valley. The presence of reactors and of a management complex for nuclear wastes on the reservation of the Idaho National Engineering Laboratory (INEL), near the river , give additional cause for concern over the consequences of a rupture of Mackay Dam. The objective of this report is to calculate and route the flood wave resulting from the hypothetical failure of Mackay Dam downstream to the INEL. Both a full and a 50 percent partial breach of this dam are investigated. Two techniques are used to develop the dam-break model. The method of characteristics is used to propagate the shock wave after the dam fails. The linear implicit finite-difference solution is used to route the flood wave after the shock wave has dissipated. The time of travel of the flood wave, duration of flooding, and magnitude of the flood are determined for eight selected sites from Mackay Dam, Idaho, through the INEL diversion. At 4.2 kilometers above the INEL diversion, peak discharges of 1,550.2 and 1,275 cubic meters per second and peak flood elevations of 1,550.3 and 1,550.2 meters were calculated for the full and partial breach, respectively. Flood discharges and flood peaks were not compared for the area downstream of the diversion because of the lack of detailed flood plain geometry. (Kosco-USGS)

Idaho↗
USGS1983

Reservoir-development impacts on surface-water quantity and quality in the Yampa River basin, Colorado and Wyoming

Development of coal resources and associated economy is accelerating in the Yampa River basin in northwestern Colorado and south-central Wyoming. Increased use of the water resources of the area will have a direct impact on their quantity and quality. As part of 18 surface-water projects, 35 reservoirs have been proposed with a combined total storage of 2.18 million acre-feet, 41% greater than the mean annual outflow from the basin. Three computer models were used to demonstrate methods of evaluating future impacts of reservoir development in the Yampa River basin. Four different reservoir configurations were used to simulate the effects of different degrees of proposed reservoir development. A multireservoir-flow model included both within-basin and transmountain diversions. Simulations indicated that in many cases diversion amounts would not be available for either type of diversion. A corresponding frequency analysis of reservoir storage levels indicated that most reservoirs would be operating with small percentages of total capacities and generally with less than 20% of conservation-pool volumes. Simulations using a dissolved-solids model indicated that extensive reservoir development could increase average annual concentrations at most locations. Simulations using a single-reservoir model indicated no significant occurrence of water-temperature stratification in most reservoirs due to limited reservoir storage. (USGS)

Water-Resources Investigations Report↗
USGS1986

Simulation of streamflow temperatures in the Yakima River basin, Washington, April-October 1981

The effects of storage, diversion, return flow, and meteorological variables on water temperature in the Yakima River, in Washington State, were simulated, and the changes in water temperature that could be expected under four alternative-management scenarios were examined for improvement in anadromous fish environment. A streamflow routing model and Lagrangian streamflow temperature model were used to simulate water discharge and temperature in the river. The estimated model errors were 12% for daily discharge and 1.7 C for daily temperature. Sensitivity analysis of the simulation of water temperatures showed that the effect of reservoir outflow temperatures diminishes in a downstream direction. A 4 C increase in outflow temperatures results in a 1.0 C increase in mean irrigation season water temperature at Umtanum in the upper Yakima River basin, but only a 0.01C increase at Prosser in the lower basin. The influence of air temperature on water temperature increases in a downstream direction and is the dominant influence in the lower basin. A 4 C increase in air temperature over the entire basin resulted in a 2.34 C increase in river temperatures at Prosser in the lower basin and 1.46 C at Umtanum in the upper basin. Changes in wind speed and model wind-function parameters had little effect on the model predicted water temperature. Of four alternative management scenarios suggested by the U.S. Bureau of Indian Affairs and the Yakima Indian Nation, the 1981 reservoir releases maintained without diversions or return flow in the river basin produced water temperatures nearest those considered as preferable for salmon and steelhead trout habitat. The alternative management scenario for no reservoir storage and no diversions or return flows in the river basin (estimate of natural conditions) produced conditions that were the least like those considered as preferable for salmon and steelhead trout habitat. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1987

Effect of urbanization on the water resources of eastern Chester County, Pennsylvania

The effects of human activity on the water resources of a 207-square-mile area of eastern Chester County was evaluated. The most serious consequence of urbanization is the contamination of ground water by volatile organic compounds, which were detected in 39 percent of the 70 wells sampled. As many as nine compounds were found in one water sample, and the concentration of total volatile organic compounds was as high as 17,400 ug/L (micrograms per liter). In the Chester Valley, volatile organic compounds are moving down the hydraulic gradient caused by quarry dewatering. Movement through the quarries reduces concentrations of these compounds and removes most of them. Phenol was detected in 28 percent of 54 wells sampled, with concentrations up to 7 ug/L. Metals, except for iron and manganese, and other trace constituents generally are not a water-quality problem. However, ground water in an area in Chester Valley has been contaminated by concentrations of boron as high as 20,000 ug/L and lithium as high as 13,000 ug/L. The ground water discharges to Valley Creek, where concentrations of boron are as high as 130 ug/L and lithium as high as 800 ug/L. Concentrations of chloride as high as 2,100 mg/L (milligrams per liter) were found in a well at a former highway salt storage site. Wells completed in carbonate rock downgradient from the Pennsylvania Turnpike had chloride concentrations as high as 350 mg/L. The base-neutral organic compounds bis(2-ethylhexyl) phthalate, di-n-butyl phthalate, and 1,2-dichlorobenzene, and the pesticides alachlor, aldrian, diazanon, DDD, DDT, dieldrin, methyl parathion, picloram, and 2,4-D were detected in a few water samples in low concentrations, However, these organic compounds do not present a widespread water-quality problem. Neither acid organic compounds nor polychlorinated napthalenes (PCN) were detected in ground water. The growth of public water and sewer systems has resulted in a significant interbasin transfer of water. Estimates for 1984 range from a net loss of 630 million gallons in the Valley Creek basin to a net gain of 783 million gallons in the Chester Creek basin. The quantity of wastewater discharged from treatment plants generally correlates well with the altitude of the water table and poorly with water use or precipitation, indicating substantial ground-water infiltration. Estimated ground-water infiltration to the West Goshen treatment plant for 1980-84 was 0.8 cubic feet per square mile, or 10 percent of the long-term average flow of Chester Creek. Estimated ground-water infiltration to the Valley Forge sewer system was as high as 4.9 million gallons per day. Dewatering operations at two active quarries in Chester Valley have lowered water levels locally and increased the range of the fluctuation of the local water table. The spread of the cones of depression caused by quarry pumping is limited by geologic and hydrologic controls. Pumping of high-capacity wells in Chester Valley has caused small local cones of depression and may have caused some reaches of Valley Creek or its tributaries to lose water. One of the greatest effects of human activity on the surface-water system has been the accumulation of organic compounds, particularly PCB and pesticides, on stream-bottom material. PCB, DDE, and dieldrin were found in bottom material from all eight streams sampled. Land-use changes in 10 selected subbasins were quantified and related to stream-benthic invertebrate diversity index. from 1970-80, the diversity index increased at all sites. Subbasins that had a greater change in land use had a greater increase in diversity index. The increase may be due to the banning of certain pesticides such as DDT, a decreasing use of pesticides in urbanizing subbasins, or flushing or burial of older pesticide-contaminated sediment.

Pennsylvania↗
USGS1996

Initial effects of Stagecoach Reservoir on discharge, water-quality characteristics, and suspended-sediment loads in the Yampa River, northwestern Colorado

The construction and filling of Stagecoach Reservoir on the Yampa River during 1988-91 were done to enhance water management and to use local water resources. To assess the initial effects of the reservoir on the hydrology of the upper Yampa River, physical, chemical, and biological data were collected at a site upstream (YR-1) during water years 1989-92 and a site downstream (YR-2) from the reservoir during water years 1985-92 and at two sites in the reservoir during 1990-92. Annual suspended-sediment loads were determined for the Yampa River for water years 1985-92, and sediment retention in Stagecoach Reservoir was estimated. The initial filling of the 33,275-acre-foot reservoir proceeded slower than expected because inflow from the Yampa River was about 50 to 73 percent of average during water years 1989-91. Secchi-disk measurements in Stagecoach Reservoir ranged from 2.5 to 18 feet. Algal growth and sediment transport during stormy weather decreased water clarity, and possible algal grazing by zooplankton and sediment deposition improved water clarity. Water temperature in the reservoir ranged from 0 to 22 degrees Celsius, and thermal stratification was maintained during summer. Values of pH ranged from 7.2 in the hypolimnion to 8.9 in the epilimnion. Changes in pH were related to photosynthesis and respiration. Concentrations of dissolved oxygen in the reservoir ranged from 0 milligram per liter in the hypolimnion to 13 milligrams per liter in the epilimnion. Average 5-day biochemical-oxygen-demand rates ranged from 0.33 to 0.46 milligram per liter per day. Oxygen production from photosynthesis was greatest in the epilimnion; oxygen depletion from respiration was characteristic in the hypolimnion. Near or above average inflow might decrease the incidence of anaerobic conditions. Specific conductance in the reservoir ranged from 414 to 520 microsiemens per centimeter at 25 degrees Celsius, depending on the specific conductance of inflow from the Yampa River. The water was a very hard, calcium bicarbonate type. Nitrogen input to the reservoir was mostly as organic nitrogen that ranged in concentration from less than 0.18 to about 1.0 milligram per liter. Concentrations of dissolved phosphorus in the inflow of the Yampa River ranged from less than 0.01 to 0.06 milligram per liter. Decomposition of organic material and release of nutrients from sediments under reducing conditions were probable causes for dissolved-ammonia concentrations near the reservoir bottom to increase to maximum values of 0.9 to 1.6 milligrams per liter as nitrogen during thermal stratification in summer. Dissolved phosphorus also increased in the same conditions to a range of 0.32 to 0.35 milligram per liter. Except for concentrations of total recoverable manganese that ranged from 210 to 440 micrograms per liter near the reservoir bottom, most concentrations of 20 trace constituents were measured at or near analytical detection limits. A total of 119 phytoplankton from 7 phyla was identified in Stagecoach Reservoir during 1990-92. Cyanophyta (blue-green algae) accounted for most of the cell counts. Cyanophyta blooms of Aphanizomenon and Aphanocapsa developed during 1990-92, and photosynthesis caused concentrations of dissolved oxygen to exceed 150-percent saturation in the epilimnion. Diversity index values for phytoplankton ranged from 0.05 to 3.06. Values of diversity index during the summer of 1992 indicated that the community diversity of algae could be greatest in spring and least in fall. All colony counts of fecal coliform bacteria in the reservoir during 1990-92 were less than criteria limits set by the State of Colorado. During water years 1985-88 (preconstruction period), at a site on the Yampa River downstream from the proposed damsite, and water years 1989-92 (post-construction period), at a site upstream from the dam, annual loads of suspended sediment ranged from 2,480 to 22,650 tons. The average annual suspended-sediment load for th

Water-Resources Investigations Report↗
USGS1996

Influences of environmental settings on aquatic ecosystems in the Apalachicola-Chattahoochee-Flint River basin

The watershed boundary of the Apalachicola-Chattahoochee-Flint (ACF) River basin defines an aquatic ecosystem whose water quality is the result of complex interactions of natural and human influences on land and water resources. Topics relating to the basin's environmental setting-its physical, biological, and cultural characteristics-are summarized to provide an understanding of factors that influence water quality and the health of aquatic ecosystems. The ACF River basin lies partly in southwestern Georgia, southeastern Alabama, and northwestern Florida and covers 19,800 square miles in the Blue Ridge, the Piedmont, and the Coastal Plain Provinces. The basin includes the drainages of the Chattahoochee River and the Flint River, which meet to form the Apalachicola River. The Apalachicola River flows into the Gulf of Mexico at Apalachicola Bay. Basin hydrology and water quality are influenced by 16 mainstem reservoirs, 13 of which are on the Chattahoochee River. Ground water in the basin is contained in six aquifers-the surficial aquifer system, the Floridan aquifer system, the Claiborne aquifer, the Clayton aquifer, the Providence aquifer, and the crystalline-rock aquifer. Physiography, climate, and hydrology of the ACF River basin provide natural conditions that support a rich and abundant diversity of plants and animals. Although most of the ACF River basin has been altered by human activities, the basin's environment is noteworthy for its remaining biological diversity and the role it plays in sustaining biological productivity in Apalachicola Bay. The Bay produces 90 percent of Florida's and 13 percent of the Nation's oyster harvest; and functions as a nursery for penaeid shrimp, blue crabs, and a variety of fin fish. The diversity of the basin's aquatic fauna is noteworthy because the basin is home to (1) the largest number of fish species among Gulf Coast drainages east of the Mississippi River, (2) the largest assemblage of freshwater fish in Florida, (3) the largest number of mollusc species among western Florida drainages, and (4) the highest species density of amphibians and reptiles on the continent north of Mexico. Population of the ACF River basin in 1990 was estimated at 2.6 million. Nearly 90 percent of the total population lived in Georgia, and nearly 60 percent lived in the Metropolitan Atlanta area. The 1990 basin population is projected to increase by 15 percent to 3.0 million by the year 2000, and by 30 percent to 3.4 million by 2010. The largest increases in populations are projected for the Metropolitan Atlanta area. In 1972-76, approximately 59 percent of the basin was covered by forest, 29 percent was agricultural, 5 percent was wetland, 4 percent was urban, and 3 percent was water or barren land. Most of the original land cover of the basin has been transformed by human activity. Timber is the basin's largest cash crop and most forests consist of second-growth stands or large acreages of planted pine. The dominant agricultural land use in the Piedmont Province is pasture and confined feeding for dairy, livestock, and poultry production. Row-crop agriculture, orchards, and silviculture are most common in the Coastal Plain Province. The top five crops in order from most to least acres harvested in 1990 were peanuts, corn, soybeans, wheat, and cotton. The water in the basin is used for public and industrial supply, irrigation, power generation, navigation, and recreation. Although most public-supply withdrawals in the Blue Ridge and Piedmont Provinces are from surface-water sources, with the exception of counties near or immediately below the Fall Line, all publicly supplied water in the Coastal Plain is withdrawn from ground-water sources. Ground water supplied 18 percent of the basin's population served by public supply. Total water withdrawn in the ACF River basin in 1990 was 2,098 million gallons per day (Mgal/d), of which Georgia withdrew 82 percent and Florida and Alabama each withdrew 9 percent. Power generation is the single largest water use. Sixteen of the basin's 22 power generating plants are located along the mainstem of the Chattahoochee River. The U.S. Army Corps of Engineers maintains a navigation channel from the mouth of the Apalachicola River to Columbus, Ga., on the Chattahoochee River and to Bainbridge, Ga., on the Flint River. Water quality in the basin is influenced by the operation of 137 municipal wastewater-treatment facilities. In 1990, 354 Mgal/d of municipal wastewater was discharged within the ACF River basin. Eighty-eight percent of the wastewater was discharged into the Chattahoochee River basin, 10.6 percent into the Flint River basin, and 1.4 percent into the Apalachicola River basin. Two-thirds of the 938 stream miles in the Georgia portion of the ACF River basin having water quality that does not meet or only partially meets the designated-use criteria in the Chattahoochee River basin. The Chattahoochee River is the most heavily-used water resource both in the ACF River basin and in Georgia. Urban runoff or unknown nonpoint sources are cited as the causes of water-quality regulations in 72 percent of violations. The remaining causes primarily are combined sewer overflows in the Atlanta area, and discharges from municipal or industrial treatment facilities with inadequate treatment capabilities or operational deficiencies.

Alabama, Florida, Georgia↗