Publications

Perchlorate (ClO4−) has been detected widely in groundwater and soils of the southwestern United States. Much of this ClO4− appears to be natural, and it may have accumulated largely through wet and dry atmospheric deposition. This study evaluates the isotopic composition of natural ClO4− indigenous to the southwestern U.S. Stable isotope ratios were measured in ClO4− (δ18O, Δ17O, δ37Cl)...

The proportion of an aquifer with constituent concentrations above a specified threshold (high concentrations) is taken as a nondimensional measure of regional scale water quality. If computed on the basis of area, it can be referred to as the aquifer scale proportion. A spatially unbiased estimate of aquifer scale proportion and a confidence interval for that estimate are obtained...

PDF version of a presentation on assessing water resources given at the 2010 National Water-Quality Monitoring Conference.

Equations have been defined for estimating the depth of water for floods having a 67-, 50-, 20-, 10-, 4-, 2-, and 1-percent chance exceedance on rural streams in Alabama. Multiple regression analyses of streamgage data were used to define the equations. Eight basin and climatic characteristics that were computed by using a geographical information system were evaluated as independent...

In this work, we use stable Zn and Cu isotopes to identify the sources and timing of the deposition of these metals in a sediment core from Lake Ballinger near Seattle, Washington, USA. The base of the Lake Ballinger core predates settlement in the region, while the upper sections record the effects of atmospheric emissions from a nearby smelter and rapid urbanization of the watershed...

All groundwater pumped is balanced by removal of water somewhere, initially from storage in the aquifer and later from capture in the form of increase in recharge and decrease in discharge. Capture that results in a loss of water in streams, rivers, and wetlands now is a concern in many parts of the United States. Hydrologists commonly use analytical and numerical approaches to study...

The Potsdam Sandstone of Cambrian age forms a transboundary aquifer that extends across northern New York and into southern Quebec. The Potsdam Sandstone is a gently dipping sequence of arkose, subarkose, and orthoquartzite that unconformably overlies Precambrian metamorphic bedrock. The Potsdam irregularly grades upward over a thickness of 450 m from a heterogeneous feldspathic and...

The Everglades Depth Estimation Network (EDEN) is an integrated network of real-time water-level gaging stations, ground-elevation models, and watersurface models designed to provide scientists, engineers, and water-resource managers with current (2000-present) water-depth information for the entire freshwater portion of the greater Everglades. The generation of EDEN waterlevel surfaces...

The U.S. Geological Survey requires that each Water Science Center prepare a surface-water quality-assurance plan to describe policies and procedures that ensure high quality surface-water data collection, processing, analysis, computer storage, and publication. The Georgia Water Science Center's standards, policies, and procedures for activities related to the collection, processing...

The United States Geological Survey (USGS) Georgia Water Science Center (WSC) maintains a long-term hydrologic monitoring network of more than 317 real-time streamgages, more than 180 groundwater wells of which 31 are real-time, and 10 lake-level monitoring stations. One of the many benefits of data collected from this monitoring network is that analysis of the data provides an overview...

How groundwater flow varies when long-term external conditions change is little documented. Geochemical evidence shows that sea-level rise at the end of the last glacial period led to a shift in the flow patterns of coastal groundwater beneath Florida.

Approximately 25,000 new households and thousands of new jobs will be established in an area that extends from southwest to northeast of Baltimore, Maryland, as a result of the Federal Base Realignment and Closure (BRAC) process, with consequent new demands on the water resources of the area. The U.S. Geological Survey, in cooperation with the Maryland Department of the Environment, has...