Water resources of Deuel and Hamlin counties, South Dakota

An estimated 8.5 million acre-feet of water is stored in three major and several minor aquifers in the glacial drift in Deuel and Hamlin Counties, SD. The Big Sioux aquifer, underlying the valley of the Big Sioux River and some of its tributaries, contains an estimated 0.5 million acre-feet of water in storage, but is, along with other small surficial aquifers, the most easily developed source of good-quality groundwater. These aquifers can yield enough to supply large capacity wells in many areas. The Big Sioux, and other surficial aquifers, are hydraulically connected with the Big Sioux River or other streams and some lakes in the area, so that these aquifers can receive recharge from or discharge water to those streams and lakes. The other two major aquifers in the drift are the Prairie Coteau aquifers, buried beneath 3 to 364 feet of till, and the Altamont aquifers, buried beneath 150 to 820 feet of till and commonly overlying the bedrock surface. The only known aquifer in the bedrock is the sandstone of the Dakota Formation, which contains an estimated 5 million acre-feet of saline water. (USGS)