Appraisal of water from surficial-outwash aquifers in Todd County and parts of Cass and Morrison counties, central Minnesota

Water-Resources Investigations Report 83-4156

Prepared in cooperation with Todd, Cass, and Morrison Counties Steering Committee and the Minnesota Department of Natural Resources



Outwash deposits consisting of medium to very coarse sand constitute a major aquifer in Todd County and in parts of Cass and Morrison Counties. The outwash ranges in thickness from 0 to 150 feet. Depth to water is generally less than 15 feet, and annual water-level fluctuations are less than 5 feet. Aquifer-test results indicate that transmissivities range from 4,600 to 18,500 feet squared per day and storage coefficients range from 0.10 to 0.25. Yields of more than 2,000 gallons per minute can be obtained locally from properly constructed wells.

Average annual precipitation is 25.93 inches, and average annual recharge to the aquifer is estimated to be 8 inches. Base-flow measurements of the Long Prairie River between Long Prairie and Motley during October 1978 and October 1979 indicate average net gains of 0.85 and 1.3 cubic feet per second per river mile.

The water is a calcium bicarbonate type and is generally suitable for most uses. However, elevated concentrations of selected chemicals in local areas may require treatment of the water for specialized uses. The water is hard to very hard with dissolved-solids concentrations ranging from about 200 to 400 milligrams per liter. Locally, nitrate concentrations are as much as 6.4 milligrams per liter. Residuals of pesticides are present but do not exceed recommended limits as established by the U.S. Environmental Protection Agency for domestic consumption.

Results from numerical modeling experiments indicate that, with proper development, the ground-water system can accommodate additional withdrawals. One experiment indicated that reduction in recharge from 8 to 4 inches annually over 4 years, and anticipated increases in pumping from 2.1 million gallons per day (1978 pumpage) to 7.7 million gallons per day, would cause water levels to decline regionally only about 9 feet and ground-water discharge to streams to decline only about 20 percent.

Study Area

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Appraisal of water from surficial-outwash aquifers in Todd County and parts of Cass and Morrison counties, central Minnesota
Series title:
Water-Resources Investigations Report
Series number:
Year Published:
U.S. Geological Survey
Publisher location:
St. Paul, MN
Contributing office(s):
Minnesota Water Science Center
Document: v, 43 p.; 6 Plates: 29.82 x 30.77 inches or smaller
United States
Cass County, Morrison County, Todd County
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