Publications

In 1991, the U.S. Geological Survey (USGS), Department of the Interior, began a National Water-Quality Assessment (NAWQA) Program. The long-term goals of the NAWQA Program are to describe the status of and trends in the quality of a large, representative part of the Nation's surface- and ground-water resources and to identify the major natural and human factors that affect the quality of these res

No abstract available.

Annual ground-water withdrawals in Arizona were 2.9, 3.3, 3.6, and 3.4 million acre-feet for calendar years 1987. 1988, 1989, and 1990. The average annual ground-water withdrawal for Arizona from 1980-89 was 3.7 million acre-feet, which was the lowest average annual withdrawal for any decade since the 1940' s. Since 1947, annual ground-water withdrawals in Arizona were at the lowest rate in 1983 a

A map showing ground-water levels in Buckingham and Wrightstown Townships, Bucks County, Pennsylvania, was constructed from water levels measured in 251 wells and from 3 reported elevations of quarry sumps from June 1992 through January 1993. Observed water-level altitudes range from 459 feet above sea level along Burnt House Hill Road, south- west of Mechanicsville, to 10 feet above sea level alo

The geologic units in the vicinity of a hazardous- waste landfill near Pinewood, S.C., were divided into hydrogeologic units on the basis of lithologic and hydrologic characteristics. A quasi-3- dimensional finite-difference ground-water-flow model was constructed to represent the hydrogeologic flamework. The simulation results indicate that if non-reactive constituents were released to the Lang S

The average recharge rate in the Portland Basin, in northwestern Oregon and southwestern Washington, is estimated to be about 22.0 inches per year. Of that amount, precipitation accounts for about 20.8 inches per year, runoff into drywells 0.9 inches per year, and on-site waste disposal about 0.4 inches per year. Recharge is highest, about 49 inches per year, in the Cascade Range. Recharge is lowe

Vadnais Lake is located in northern Ramsey County, Minnesota. The lake is managed by the St. Paul Water Utility for storage of municipal water supplies that are provided to residents of St. Paul and surrounding communities. In recent years, algal blooms in Vadnais Lake have caused taste and odor problems in St. Paul's municipal water supply. This problem has potentially been exacerbated by phospho

The Precipitation-Runoff Modeling System (PRMS) model of the U.S. Geological Survey was used to simulate the hydrologic effects of timber management in 11 small, upland drainage basins of the Coast Range in Oregon. The coefficients of determination for observed and simulated daily flow during the calibration periods ranged from 0.92 for the Flynn Creek Basin to 0.68 for the Priorli Creek Basin; pe

Ground-water capture zone boundaries for individual pumped wells in a confined aquffer were delineated by using groundwater models. Both analytical and numerical (semi-analytical) models that more accurately represent the $round-water-flow system were used. All models delineated 2-dimensional boundaries (capture zones) that represent the areal extent of groundwater contribution to a pumped well. T

Nutrient and organic compound data from the U.S. Geological Survey and the U.S. Environmental Protection Agency STORET data bases provided information for development of a preliminary conceptual model of spatial and temporal ground-water quality in the upper Snake River Basin. Nitrite plus nitrate (as nitrogen; hereafter referred to as nitrate) concentrations exceeded the Federal drinking-water re

Computerized Geographic Information Systems (GIS) have become viable and valuable tools for managing,analyzing, creating, and displaying data for three-dimensional finite-difference ground-water flow models. Three GIS applications demonstrated in this study are: (1) regridding of data arrays from an existing large-area, low resolution ground-water model to a smaller, high resolution grid; (2) use

Samples of ground water and tertiary-treated water were evaluated to determine the distribution of injected water and trihalomethane compounds in the Hueco bolson aquifer near El Paso, Texas. Chloride and nitrate concentrations and oxygen-18/oxygen-16 (δ18O) values were used with end-member mixing analysis to estimate the fractional contributions of injected water, irrigation-affected water, salin