Publications

We present an application of an equilibrium-based solute transport model to a pH-modification experiment conducted on the Snake River, an acidic, metal-rich stream located in the Rocky Mountains of Colorado. During the experiment, instream pH decreased from 4.2 to 3.2, causing a marked increase in dissolved iron concentrations. Model application requires specification of several...

Water, bed sediment, and biota were sampled in streams from Butte to below Missoula as part of a program to characterize aquatic resources in the upper Clark Fork basin of western Montana. Sampling stations were located on the Clark Fork and major tributaries. Water-quality data were obtained periodically at 16 stations during October 1994 through September 1995 (water year 1995). Data...

Groundwater age dating through the combination of transient tracer methods (chlorofluorocarbons (CFCs) and tritium/helium 3 (3H/3He)) and groundwater flow path analysis is useful for investigating groundwater travel times, flow patterns, and recharge rates, as demonstrated by this study of the homogeneous shallow, unconfined Kirkwood-Cohansey aquifer system in the southern New Jersey...

1. The relationships between three habitat scales and lotic invertebrate species composition were investigated for the 15 540 km2 Yakima River basin in south-central Washington, U.S.A. 2. The three spatial scales were sample (the sampled riffle), reach (a length of ten–twenty stream widths) and segment (a length of stream of nearly uniform slope and valley form having no change in stream...

A geographic information system (GIS) procedure was developed to compile low-altitude aerial photography, digitized data, and land-use data from U.S. Department of Agriculture Consolidated Farm Service Agency (CFSA) offices into a high-resolution (approximately 5 meters) land-use GIS data set. The aerial photography consisted of 35-mm slides which were scanned into tagged information...

No abstract available.

This data set consists of digital aquifer boundaries for the High Plains aquifer in the central United States. The High Plains aquifer extends from south of 32 degrees to almost 45 degrees north latitude and from 96 degrees 30 minutes to almost 104 degrees west longitude. The area covers 174,000 square miles and is present in Texas, Oklahoma, New Mexico, Kansas, Colorado, Nebraska...

Ground water in terrace deposits of the South Platte River alluvial aquifer near Greeley, Colorado, USA, had a median nitrate concentration of 1857 μmol l−1. Median nitrate concentrations in ground water from adjacent floodplain deposits (468 μmol l−1) and riverbed sediments (461 μmol l−1), both of which are downgradient from the terrace deposits, were lower than the median concentration...

Irrigated agriculture has a long history in the Western United States, beginning with Native American Indians. After passage of the Reclamation Act of 1902, the United States Government began building and subsidizing irrigation projects to foster settlement and development of the arid and semi-arid areas of the Western United States (National Research Council, 1989). Precipitation in the

Improvements in the field sampling, preservation, and determination of trace metals in natural waters have made many analyses more reliable and less affected by contamination. The speciation of trace metals, however, remains controversial. Chemical model speciation calculations do not necessarily agree with voltammetric, ion exchange, potentiometric, or other analytical speciation...

Ground-water withdrawal from a confined or semiconfined aquifer causes three-dimensional deformation in the pumped aquifer and in adjacent layers (overlying and underlying aquifers and aquitards). In response to the deformation, hydraulic head in the adjacent layers could rise or fall almost immediately after the start of pumping. This deformation-induced effect suggest that an adjacent...

Nonlinear regression is useful in ground-water flow parameter estimation, but problems of parameter insensitivity and correlation often exist given commonly available hydraulic-head and head-dependent flow (for example, stream and lake gain or loss) observations. To address this problem, advective-transport observations are added to the ground-water flow, parameter-estimation model...