Publications

The high demand for water, the recent multiyear drought (1999-2007), and projections of global warming have raised questions about the long-term sustainability of water supply in the southwestern United States. In this study, the potential effects of specific levels of atmospheric warming on water-year streamflow in the Colorado River basin are evaluated using a water-balance model, and...

Water-resource managers need to forecast streamflow in the Lower Colorado River Basin to plan for water-resource projects and to operate reservoirs for water supply. Statistical forecasts of streamflow based on historical records of streamflow can be useful, but statistical assumptions, such as stationarity of flows, need to be evaluated. This study evaluated the relation between...

The International Bedload-Surrogate Monitoring Workshop (http://www.nced.umn.edu/BRIC_2007.html), organized by the Bedload Research International Cooperative (BRIC; www.bedloadresearch.org), was held to assess and abet progress in continuous, semiautomated, or fully automated (surrogate) technologies for monitoring bed load discharge in gravel-, sand-, and mixed gravel-sand-bedded rivers...

Regulatory agencies are often charged with the task of setting site-specific numeric water quality standards for impaired streams. This task is particularly difficult for streams draining highly mineralized watersheds with past mining activity. Baseline water quality data obtained prior to mining are often non-existent and application of generic water quality standards developed for...

Current-use pesticides (CUPs) and banned organochlorine compounds (OCCs) were measured in precipitation (snowpack and rain) and lake sediments from two national parks in the Western United States to determine their occurrence and distribution in high-elevation environments. CUPs frequently detected in snow were endosulfan, dacthal, and chlorothalonil in concentrations ranging from 0.07...

Advanced borehole-geophysical methods were used to assess the geohydrology of fractured crystalline bedrock in 31 of 64 boreholes on the southern part of Manhattan Island, NY in preparation of the construction of a new water tunnel. The study area is located in a highly urbanized part of New York City. The boreholes penetrated gneiss, schist, and other crystalline bedrock that has an...

Although the pelagic fish community of the upper San Francisco Estuary historically has shown substantial variability, a recent collapse has captured the attention of resource managers, scientists, legislators, and the general public. The ecological and management consequences of the decline are most serious for delta smelt (Hypomesus transpacificus), a threatened species whose narrow...

We examined potential sources and the temporal dynamics of arsenic (As) in the slightly alkaline waters of the Wallkill River, northwestern New Jersey, where violations of water-quality standards have occurred. The study design included synoptic sampling of stream water and bed sediments in tributaries and the mainstem, hyporheic-zone/ground water on the mainstem, and seasonal and...

This report documents the Conduit Flow Process (CFP) for the modular finite-difference ground-water flow model, MODFLOW-2005. The CFP has the ability to simulate turbulent ground-water flow conditions by: (1) coupling the traditional ground-water flow equation with formulations for a discrete network of cylindrical pipes (Mode 1), (2) inserting a high-conductivity flow layer that can...

The U.S. Geological Survey, in cooperation with the San Antonio Water System, conducted a 4-year study during 2002?06 to identify major flow paths in the Edwards aquifer in northeastern Bexar and southern Comal Counties (study area). In the study area, faulting directs ground water into three hypothesized flow paths that move water, generally, from the southwest to the northeast. These...

Water availability became a concern in Rhode Island during a drought in 1999, and further investigation was needed to assess the current demands on the hydrologic system from withdrawals during periods of little to no precipitation. The low ground-water levels and streamflows measured in Rhode Island prompted initiation of a series of studies on water use and availability in each major...

During the summers of 2005 and 2006 the U.S. Geological Survey, in cooperation with the Texas Commission on Environmental Quality, evaluated nutrient and biological conditions in small streams in parts of the Edwards Plateau of Central Texas. Land-cover analysis was used to select 15 small streams that represented a gradient of conditions with the potential to affect nutrient...