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The western arm of the Black Rock Desert, Nevada, includes several distinct hydrothermal systems, some of which exceed 150 C and may exceed 200 C at depth, determined on the basis of chemical geothermometry. The cation composition of the thermal water appears to be controlled by aluminosilicate minerals that are...

Sixty-eight percent of the 22.6-square-mile Valley Creek basin is underlain by Cambrian and Ordovician limestone and dolomite. Ground water flows through a network of interconnected secondary openings; primary porosity is virtually nonexistent. Some of these openings have been enlarged by solution. Secondary porosity and permeability exhibit great spatial variability, and...

Five streamflow-gaging stations were installed in the Rock Creek basin north of the Milk River near Hinsdale, Montana. Streamflow was monitored at these stations and at an existing gaging station upstream on Rock Creek from May 1983 through September 1987. The data collected were used to describe the flow characteristics...

Thick, glacial sand and gravel deposits provide most ground-water supplies in Kalamazoo County. These deposits range in thickness from 50 to about 600 feet in areas that overlie buried bedrock valleys. Most domestic wells completed at depths of less than 75 feet in the sands and gravels yield adequate water...

The potential for developing water supplies from the alluvium along the Powder River between Sussex, Wyoming, and Moorehead, Montana, is very limited. The areal extent and saturated thickness of the alluvium are not large. Water in the alluvium primarily is derived from seepage from the river, which goes dry periodically....

Groundwater samples were collected from the shallow unconfined aquifer at the Pueblo Depot Activity (Colorado) landfill and downstream from the landfill. The Pueblo Depot Activity is a U.S. Department of the Army facility in southeastern Colorado about 15 miles east of Pueblo, Colorado. The land-fill is underlain by upland alluvial...

Computer software was written to randomly select sites for a ground-water-quality sampling network. The software uses digital cartographic techniques and subroutines from a proprietary geographic information system. The report presents the approaches, computer software, and sample applications. It is often desirable to collect ground-water-quality samples from various areas in a study...

A major objective of the Gulf Coast Regional Aquifer-System Analysis is to use digital models of regional groundwater flow systems to develop better understanding and to improve management of the resource. Modeling is used to synthesize information about the aquifer systems and to test hypotheses about the relative importance of...

Selected water-quality properties and constituents of stormflow and base flow were compared to determine the relation between the degree of urbanization and the water quality in a drainage basin. Samples were collected during three flow categories (rising stage and falling stage of stormflow and base flow) at 18 sites on...

In Cibola Valley, Arizona, water is pumped from the Colorado River to irrigate crops and to maintain wildlife habitat. Unused water percolates to the water table and, as groundwater, moves downgradient into areas of phreatophytes, into a drainage ditch, out of the flood plain, and back to the river. In...

Unlined hazardous-waste disposal sites at the U.S. Marine Corps Air Station, Cherry Point, North Carolina, are located near drinking-water supply wells that tap the Castle Hayne aquifer. Hydrogeologic and water-quality data were collected near 2 of these sites from 12 monitoring wells installed in May through June 1987. Near the northernmost...

Batch-mixing experiments to evaluate postmining water quality at the Cordero Mine were conducted by the U.S. Geological Survey during 1984 to 1985. Contact of groundwater from the spoil aquifer with fresh spoil material caused only small changes in major-element concentrations and in pH, unless sulfide oxidation or contact with soluble...

Streamflow hydrographs of 309 streamflow stations in Pennsylvania were analyzed by using three computer-assisted empirical methods--local-minimum , fixed-interval, and sliding-interval--to separate the ground-water and surface-runoff components. The 2-, 5-, 10-, and 25-year base-flow-recurrence intervals were determined for each station. The 50- and 100-year recurrence intervals were determined for stations with...

A simple method of weather-type classification, based on a conceptual model of pressure systems that pass through the Philadelphia, Pennsylvania, area, has been developed. The only inputs required for the procedure are daily mean wind direction and cloud cover, which are used to index the relative position of pressure systems...