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The study of agricultural chemicals is one of five national priority topics being addressed by the National Water-Quality Assessment (NAWQA) Program in its second decade of studies, which began in 2001. Seven watersheds across the Nation were selected for the NAWQA agricultural-chemical topical study. The watersheds selected represent a range...

Areas contributing recharge and sources of water to a production well field in the Village of Harrisville and to a production well field in the Town of Richmond were delineated on the basis of calibrated, steady-state ground-water-flow models representing average hydrologic conditions. The study sites represent contrasting glacial valley-fill settings....

Atmospheric mercury is thought to be an important source of mercury present in fish, resulting in numerous local, statewide, tribal, and province-wide fish consumption advisories in the United States and Canada (U.S. Environmental Protection Agency, 2007a). To understand how mercury occurs in the atmosphere and its potential to be transferred...

This report presents the results of a study by the U.S. Geological Survey, done in cooperation with the Oregon Department of Environmental Quality and Deschutes County, to develop a better understanding of the effects of nitrogen from on-site wastewater disposal systems on the quality of ground water near La Pine...

No abstract available....

Time-lapse geophysical tomography can provide valuable qualitative insights into hydrologic transport phenomena associated with aquifer dynamics, tracer experiments, and engineered remediation. Increasingly, tomograms are used to infer the spatial and/or temporal moments of solute plumes; these moments provide quantitative information about transport processes (e.g., advection, dispersion, and rate-limited mass transfer)...

This report presents an assessment of land-use and land-cover (LU/LC) change in the Southern California Mountains ecoregion for the period 1973-2001. The Southern California Mountains is one of 84 Level-III ecoregions as defined by the U.S. Environmental Protection Agency (EPA). Ecoregions have served as a spatial framework for environmental resource...

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...

Heavy water use from the Cretaceous Middendorf aquifer in South Carolina has created a large, regional cone of depression in the potentiometric surface of the Middendorf aquifer in Charleston and Berkeley Counties, South Carolina. Water-level declines of up to 249 feet have been observed in wells over the past 125...

The Everglades Depth Estimation Network (EDEN) offers a consistent and documented dataset that can be used to guide large-scale field operations, to integrate hydrologic and ecological responses, and to support biological and ecological assessments that measure ecosystem responses to the Comprehensive Everglades Restoration Plan (Telis, 2006). Ground elevation data for...

This report describes a monthly water-balance model driven by a graphical user interface, referred to as the Thornthwaite monthly water-balance program. Computations of monthly water-balance components of the hydrologic cycle are made for a specified location. The program can be used as a research tool, an assessment tool, and a...

Global inputs of NOx are dominated by fossil fuel combustion from both stationary and vehicular sources and far exceed natural NOx sources. However, elucidating NOx sources to any given location remains a difficult challenge, despite the need for this information to develop sound regulatory and mitigation strategies. We present results from a regional-scale...

Samples of street mud, suspended and bottom sediment in canals discharging to Lake Ponchartrain, and suspended and bottom sediment in the lake were collected and analyzed for chemical constituents to help evaluate the effects of Hurricanes Katrina and Rita and the subsequent unwatering of New Orleans, Louisiana. The approach used...

This report documents Luca (Let us calibrate), a multiple-objective, stepwise, automated procedure for hydrologic model calibration and the associated graphical user interface (GUI). Luca is a wizard-style user-friendly GUI that provides an easy systematic way of building and executing a calibration procedure. The calibration procedure uses the Shuffled Complex Evolution...

In March 2006, the U.S. Geological Survey (USGS) held the first Scientific Information Management (SIM) Workshop in Reston, Virginia. The workshop brought together more than 150 SIM professionals from across the organization to discuss the range and importance of SIM problems, identify common challenges and solutions, and investigate the use...

This report presents environmental and quality-control data from analyses of 15 pharmaceutical and 31 antibiotic compounds in water samples from streams and wells in south-central Pennsylvania. The analyses are part of a study by the U.S. Geological Survey (USGS) in cooperation with the Pennsylvania Department of Environmental Protection (PADEP) to...

The timely warning of a flood is crucial to the protection of lives and property. One has only to recall the floods of August 2, 1973, September 16 and 17, 1999, and April 16, 2007, in Somerset County, New Jersey, in which lives were lost and major property damage occurred,...

Equations that relate drainage area to bankfull discharge and channel characteristics (width, depth, and cross-sectional area) at gaged sites are needed to define bankfull-discharge and channel characteristics at ungaged sites and to provide information for watershed assessments, stream-channel classification, and design of stream-restoration projects. Such equations are most accurate if...

The U.S. Geological Survey has completed an extensive environmental study of the effects of historical mining on water and sediment quality and aquatic and riparian habitat in the Animas River watershed upstream from Silverton, Colorado. Results from this study are being used by Federal and State agencies and by the...

A study of the Hillsborough River watershed was conducted between October 1999 through September 2003 to characterize the hydrology, water quality, and interaction between the surface and ground water in the highly karstic uppermost part of the watershed. Information such as locations of ground-water recharge and discharge, depth of the...

Many agricultural and forested areas in proximity to National Wildlife Refuges (NWR) are under increasing economic pressure to develop lands for commercial or residential development. The upper portion of the Little Blackwater River watershed - a 27 square mile area within largely low-lying Dorchester County, Maryland, on the eastern shore...

Many agricultural and forested areas in proximity to National Wildlife Refuges (NWR) are under increasing economic pressure for commercial or residential development. The upper portion of the Little Blackwater River watershed - a 27 square mile area within largely low-lying Dorchester County, Maryland, on the eastern shore of the Chesapeake...

Results of the hydrologic model, flood-frequency, hydraulic model, and flood-hazard analysis of the Blackberry Creek watershed in Kendall County, Illinois, indicate that the 100-year and 500-year flood plains cover approximately 3,699 and 3,762 acres of land, respectively. On the basis of land-cover data for 2003, most of the land in...

DEET (N,N-diethyl-m-toluamide) is the active ingredient of most commercial insect repellents. This compound has commonly been detected in aquatic water samples from around the world indicating that DEET is both mobile and persistent, despite earlier assumptions that DEET was unlikely to enter aquatic ecosystems. DEET's registration category does not require...

Highly saline produced water was released from multiple sources during oil field operations from 1913 to 1973 at the USGS research Site A on Skiatook Lake in northeastern Oklahoma. Two pits, designed to hold produced water and oil, were major sources for release...