USGS Science⌕ Search

Geology topics

Research about Dakota County, Minnesota

Source-linked reports with geographic coverage including Dakota County, Minnesota.

6 recordsLinked to original sources
USGS1995

Hydrology and relation of selected water-quality constituents to selected physical factors in Dakota County, Minnesota, 1990-91

Selected water-quality constituents were determined in water from 5 surface-water sites and 29 wells in Dakota County, Minnesota, to search for possible relations to selected physical factors, including waste-water discharge, agricultural land, Quaternary deposits, bedrock, soil-leaching potential, and water-table depth. All surface-water samples were from the Vermillion River Basin, whose hydrologic setting was studied to determine its relation to the ground-water flow in the surrounding surficial sand aquifer. Each site was sampled from 1 to 12 times during 1990- 91. A total of 198 samples were collected; selected samples were analyzed for major inorganic ions, nutrients, and triazine content. Physical factors within the area of land assumed to be contributing water to each sampling site were determined from existing mapped or digitized sources. Nitrate concentrations in ground water were related to agricultural land and soil-leaching potential. Nitrate concentrations were large (median 13.2 milligrams per liter as nitrogen) where the percentage of agricultural land in the contributing area was large (equal to or greater than 75 percent) and where the soils had a large soil-leaching potential. Nitrate concentrations were small (median 3.2 milligrams per liter as nitrogen) where the soils had a small soil-leaching potential, despite a large percentage of agricultural land. The statistical relation was not particularly strong, however: the null hypothesis that sites with different soil-leaching potentials had the same nitrate concentrations in ground water was rejected by the Kruskal-Wallis test at only the probability P = 0.15 level. Water-table depth was not an important factor in the relation between nitrate concentrations in ground water and agricultural land. Discharge from a waste-water treatment plant provided most of the downstream loading of nitrate into the Vermillion River mainstem. Triazines were found in small concentrations (less than 2 micrograms per liter) in the Vermillion River and its tributaries. No relation was apparent between selected water-quality constituents and either Quaternary deposits or bedrock.

Minnesota↗
USGS1991

Relation of nitrate concentrations in water to agricultural land use and soil type in Dakota County, Minnesota, 1990

The quality of surface and ground water can be related to various physical factors such as land use, soil type, geology, and depth to water table. Land use in Dakota County, Minnesota, is changing: urbanization and industrialization in the north and increasing irrigation and application of agricultural chemicals in the central part of the county. The U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources, the Legislative Commission on Minnesota Resources, and the Dakota County Soil and Water Conservation District, is studying the relations between some physical factors and the quality of surface-and ground-water in Dakota County. The findings of the study can be used by local officials involved in land-use planning and management. Nitrate is commonly found in ground water in agricultural areas throughout the Midwest. The emphasis of this report is to relate differences in nitrate concentrations in ground water to agricultural land use and soil type. In addition, nitrate concentrations in streams, shallow ground water near the water table, and deeper ground water from 10 to 30 feet below the water table are tabulated for selected sites in Dakota County.

Minnesota↗
USGS1980

Baseline water quality of Schmidt, Hornbeam, and Horseshoe Lakes, Dakota County, Minnesota

Three lakes in Dakota County were sampled five times during an 18-month period to determine baseline water quality prior to construction of an interstate highway. Results of physical measurements and chemical analyses showed that the lakes were shallow, nonstratified, and nutrient enriched. Considerable seasonal variations in dissolved solids, nutrient, and dissolved-oxygen concentrations were observed. Oxygen depletion and high nutrient concentrations were characteristics of conditions under an ice cover. Blue-green algal blooms typically were established soon after ice breakup and persisted until late fall. Data from the study will be supplemented with data--collected during and after construction of the highway to assess the impact of highway construction s \d drainage on water quality of the lakes.

Minnesota↗
USGS1980

Water quality of Rogers Lake, Dakota County, Minnesota

Construction of an interstate highway is planned near Rogers Lake in Dakota County, Minn. Samples of water and bed material were collected at six sites during March 1976 to April 1978 to determine selected physical, chemical, and biological characteristics before construction. Samples were collected at least twice during each season of the year. Data derived from these samples will provide baseline information to aid in assessing the impact of highway construction on the water quality of the lake. Rogers Lake is separated into an upper and lower lake by a culvert; both were eutrophic and dominated by blue-green algae year around. Analyses of water from Rogers Lake suggest that sodium and chloride concentrations were higher than in ground water or in water in some surrounding lakes . Sodium ranged from 7.2 to 55 milligrams per liter, and chloride ranged from 15 to 30 milligrams per liter. Concentrations were highest in March 1978, when most of the lake water was frozen. Much of the sodium and chloride may have been derived from road salts used for deicing.

Minnesota↗