Research about Minnesota, South Dakota

USGS1997

Hydrogeology and ground-water quality of confined aquifers in buried valleys in Rock County, Minnesota and Minnehaha County, South Dakota

Confined glacial and bedrock aquifers are present within Quaternary and Cretaceous deposits that fill buried valleys incised in the Sioux Quartzite surface in Rock County, in southwestern Minnesota and Minnehaha County, South Dakota. This report describes the areal extent, thickness, water-bearing characteristics, water-supply potential, and water-quality characteristics of confined aquifers within buriedvalley deposits in Rock County. Hydrogeologic units present within buried-valley deposits in Rock County include unconfined and confined drift aquifers, undifferentiated Cretaceous aquifers, the Split Rock Creek aquifer, and interbedded confining units. The undifferentiated Cretaceous aquifers consist of sandstone layers within interbedded claystone and siltstone overlying the Split Rock Creek Formation or Sioux Quartzite. The Split Rock Creek Formation consisting of sand units (comprising the Split Rock Creek aquifer) and interbedded layers of siltstone and claystone, is present in buried valleys incised in the Sioux Quartzite surface in southern and possibly northeastern Rock County, Minnesota. Confined drift aquifers with thicknesses greater than 5 feet were penetrated in 6 of 10 test holes. Thicknesses of the confined drift aquifers in Rock County range from at least 2 to greater than 32 feet. Estimated horizontal hydraulic conductivity for a confined drift aquifer derived from specific-capacity information from one domestic well log was 73 feet per day. No major (thickness greater than 5 feet) undifferentiated Cretaceous aquifers were penetrated in 10 test holes. Thicknesses of the undifferentiated Cretaceous aquifers compiled from the geologic logs for four domestic wells ranged from at least 7 feet to greater than 46 feet. Estimated horizontal hydraulic conductivity for an undifferentiated Cretaceous aquifer derived from specific-capacity information from one domestic well log was 55 feet per day. Cumulative sand thicknesses for the Split Rock Creek aquifer in 10 test holes ranged from zero to 128.5 feet in 2 to 6 layers. The largest cumulative sand thicknesses were penetrated near the southern margin of the Sioux Quartzite high in northern Rock County and in an east-west trending buried valley (Brandon Embayment) entering Rock County from Minnehaha County, South Dakota. These comparatively large cumulative sand thicknesses are probably due to a high-energy depositional environment. Estimated horizontal hydraulic conductivities for the Split Rock Creek aquifer in Rock County derived from analysis of three slug tests were 0.1, 0.2, and 1 foot per day. The corresponding aquifer transmissivities, calculated as the horizontal hydraulic conductivity multiplied by the cumulative sand thickness, were 3, 16, and 130 feet squared per day. The greatest horizontal hydraulic conductivity and transmissivity estimates were for a site near the southern margin of the Sioux Quartzite high. The watersupply potential of the Split Rock Creek aquifer in Rock County is generally limited by the low transmissivity of the aquifer due to the fineness of the aquifer material (generally very fine- to fine-grained sand). Recharge to the Split Rock Creek aquifer is thought to be derived primarily from hydraulic connection to the Sioux Quartzite aquifer as infiltration of precipitation moves through the fractures and joints of the Sioux Quartzite to the Split Rock Creek aquifer. The regional directions of flow in the aquifer are to the south away from the Sioux Quartzite high and to the west in the Brandon Embayment in Minnehaha County and its east-west trending extension into Rock County. The predominant ions in water from two wells screened in confined drift aquifers in Rock County were calcium and bicarbonate and in water from a third well were calcium and sulfate. The predominant ions in water from one well screened in an undifferentiated Cretaceous aquifer in Rock County were calcium and bicarbonate and in water from a second well were calcium and sulfate. The predominant ions in water from two wells screened in the Split Rock Creek aquifer in Rock County were calcium and bicarbonate and in water from a third well were calcium and sulfate.

Minnesota, South Dakota↗

USGS1996

Physical characteristics of stream subbasins in the Hawk Creek-Yellow Medicine River basin, southwestern Minnesota and eastern South Dakota

Data that describe the physical characteristics of stream subbasins upstream from selected sites on streams in the Hawk Creek-Yellow Medicine River Basin, located in southwestern Minnesota and eastern South Dakota are presented in this report. The physical characteristics are the drainage area of the subbasin, the percentage area of the subbasin covered only by lakes, the percentage area of the subbasin covered by both lakes and wetlands, the main-channel length, and the main-channel slope. Stream sites include outlets of subbasins of at least 5 square miles, outlets of sewage treatment plants, and locations of U.S. Geological Survey low-flow, high-flow, and continuous-record gaging stations.

Minnesota, South Dakota↗

USGS1994

Physical characteristics of stream subbasins in the Lac qui Parle River basin, southwestern Minnesota and eastern South Dakota

Data describing the physical characteristics of stream subbasins upstream from selected points on streams in the Lac qui Parle River basin, located in southwestern Minnesota and eastern South Dakota, are presented in this report. The physical charac- teristics are the drainage area of the subbasin, the percentage area of the subbasin covered only by lakes, the percentage area of the subbasin covered by both lakes and wetlands, the main-channel length. and the main-channel slope. The points on the stream include outlets of subbasins of at least 5 square miles, outfalls of sewage treatment plants, and locations of U.S. Geological Survey low-flow, high-flow, and continuous-record gaging stations.

Minnesota, South Dakota↗

USGS1994

Sources and transport of sediment, nutrients, and oxygen-demanding substances in the Minnesota River basin, 1989-92

The Minnesota River, 10 major tributaries, and 21 springs were sampled to determine the sources and transport of sediment, nutrients, and oxygen- demanding substances. The study was part of a four-year assessment of non-point source pollution in the Minnesota River Basin. Runoff from tributary watersheds was identified as the primary source of suspended sediment and nutrients in the Minnesota River mainstem. Suspended-sediment, phosphorus, and nitrate concentrations were elevated in all major tributaries during runoff, but tributaries in the south-central and eastern part of the basin produce the highest annual loading to the mainstem because of higher annual precipitation and runoff in that part of the basin. Particle-size analyses showed that most of the suspended sediment in transport consisted of silt- and clay-size material. Phosphorus enrichment was indicated throughout the mainstem by total phosphorus concentrations that ranged from 0.04 to 0.48 mg/L with a median value of 0.22 mg/L, and an interquartile range of 0.15 to 0.29 mg/L. Nitrate concentrations periodically exceeded drinking water standards in tributaries draining the south-central and eastern part of the basin. Oxygen demand was most elevated during periods of summer low flow. Correlations between levels of biochemical oxygen demand and levels of algal productivity suggest that algal biomass comprises much of the oxygen-demanding material in the mainstem. Transport of sediment, nutrients, and organic carbon within the mainstem was found to be conservative, with nearly all tributary inputs being transported downstream. Uptake and utilization of nitrate and orthophosphorus was indicated during low flow, but at normal and high flow, inputs of these constituents greatly exceeded biological utilization.

Minnesota, South Dakota↗