Timothy K Cowdery (Former Employee)

A combination of chemical and dissolved gas analyses, chlorofluorocarbon age dating, and hydrologic measurements were used to determine the degree to which biogeochemical processes in a riparian wetland were responsible for removing NO3−from groundwaters discharging to the Otter Tail River in west central Minnesota. An analysis of river chemistry and flow data revealed that NO3−...

This evaluation of the water resources on the Prairie Island Indian Reservation includes data collected from 8 surface-water sites and 22 wells during 1994–97 and historical data. The Mississippi River and the lakes and wetlands connected to it are separated from the Vermillion River and the lakes and wetlands connected to it by the surficial aquifer on Prairie Island and by Lock and Dam...

A mass-balance budget of N cycling was developed for an intensive agricultural area in west-central Minnesota to better understand NO3/- contamination of ground water in the Otter Tail outwash aquifer. Fertilizer, biological fixation, atmospheric deposition, and animal feed were the N sources, and crop harvests, animal product exports, volatilization from fertilizer and manure, and...

The Mille Lacs Lake study area is a 960 mi2 area containing the ground-water and surface-water drainages to both Mille Lacs Lake and the first 12 miles of the Rum River. Within this study area, available ground water occurs in saturated, overlapping, discontinuous, partially-connected, glacially-deposited (hereinafter, glacial) aquifers and in bedrock aquifers. No extensive glacial...

Surveys of water quality in surficial, buried glacial, and Cretaceous aquifers in the Red River of the North Basin during 1991-95 showed that some major-ion, nutrient, pesticide, and radioactive-element concentrations differed by physiographic area and differed among these aquifer types. Waters in surficial aquifers in the Drift Prairie (west) and Lake Plain (central) physiographic areas...

This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the River River of the North basin study unit and to relate these findings to water-quality issues of regional and national concern. The information in primarily intended for those who are involved in water-resource management. Yet the information contained here may...

During 1993-95, the agriculture on two sandy, surficial aquifers in the Red River of the North Basin affected the quality of shallow ground water in each aquifer differently. The Sheyenne Delta aquifer, in the western part of the basin, had land-use, hydrogeological, and rainfall characteristics that allowed few agricultural chemicals to reach or remain in the shallow ground water. The...

A relatively new method for age dating recent ground water along with other investigative tools improve our understanding of land-use effects on the water quality in a surficial aquifer and adjacent streams in the Red River of the North Basin: Ground water commonly takes more than 20 years to reach depths in the surficial aquifer where it is withdrawn for use. Water withdrawn from most...

The U.S. Geological Survey has studied the ground-water quality within two areas of the Red River of the North Basin in southeastern North Dakota and west-central Minnesota. Although both areas are underlain by sandy surficial aquifers over which intensive irrigated agriculture dominates the land use, their ground-water quality differs. Ground water from the eastern study area has...

No abstract available.