Ground water in Minnesota

Ground water is the major source of water supply in Minnesota. The quantity, quality, and availability vary greatly throughout the State. This study describes the State's ground-water resources as found in each of seven major drainage basins.

Water is obtained from Quaternary glacial deposits and bedrock aquifers. Most supplies are from the drift except in the southeastern and extreme northeastern parts of the State. In the southeastern part, large quantities of water are withdrawn from sedimentary bedrock aquifers. In the northeastern part, Precambrian igneous and metamorphic rocks underlie the drift and ground-water availability is poor.

Large quantities of water are available from surficial outwash, particularly in the central part of the State. Buried outwash aquifers are difficult to locate, delineate, and evaluate. Accordingly, few have been mapped.

Water quality in much of the State is suitable for most uses. Ground water is typically hard and high in iron, Water from deep drift and bedrock in the western part of the State is highly mineralized. It may contain excessive amounts of some constituents, such as sodium, chloride, sulfate, boron, and iron.

Most ground-water use is centered around cities, the largest amounts being withdrawn in the Minneapolis-St. Paul metropolitan area. Increasing amounts are being used for irrigation, most being obtained from shallow wells in the surficial outwash deposits.

Although Minnesota is generally rich in ground-water resources, it is not without associated problems. In the western part of the State, ground-water quality is often a problem, especially in deep aquifers. Throughout the State, few buried outwash aquifers have been delineated or evaluated as to their water-yielding capabilities. Some aquifers are highly susceptible to pollution. Planned development and monitoring of water levels and water quality would be beneficial.