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Publication Date

1989

Keywords

Water quality; Water-supply; Aquifers

Abstract

ABSTRACT-The Twin Cities aquifer system in Minnesota contains five aquife~s and fou: confining units that together consist of fourteen geologic units. Unconsolidated sand and gravel aqmfers overlie bedrock sandstone and carbonate aquifers. Between 1880 and 1980, groundwater wi_thdrawals have c_aused long-term wate~ level declines of as much as 90 feet in the Prairie du Chien-Jordan aquifer and 240 feet m the deeper Mount S~monHinckley aquifer-the two major sources of groundwater supplies in the ar~a .. The estimated max1mu1:1 continuous withdrawal rate from the aquifer system is about 650 Mgal/d (million gallons per day). This compares with an average daily groundwater use on an annual basis of a~out 20~ Mgal/d from the l_ate 1970s through 1986, the last year of normal precipitation. Increas~d costs of w1t?drawmg ground water, mcreased risks of decreased groundwater quality, and increased conflicts between s1multaneo~s ~sers of gr_oundwater resources are associated with increased rates of groundwater with~rawal. The prmc1p~l physical factors affecting water-supply potential are those that control the rate at which water may be withdrawn from the Mississippi River and the Twin Cities aquifer system.

First Page

38

Last Page

47

Included in

Hydrology Commons

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