Mississippian and Pennsylvanian sedimentary rocks and Quaternary sediments in the Michigan Basin form a regional aquifer system of three aquifer units and two intervening confining units. Devonian and Mississippian shales form a low-permeability basal confining unit for the regional groundwater flow system. Mississippian and Pennsylvania sandstones and Quaternary glacial deposits supply approximately 188 million gallons/day to municipalities in the 29,000 sq mi study area. Availability of adequate amounts of potable groundwater is limited in many areas by the presence of saline groundwater (dissolved solids concentration of 1,000 to 100,000 mg/L). Saline water underlies the entire Lower Peninsula of Michigan at various depths. Brine (dissolved-solids concentration > 100,000 mg/L) is found in the deeper parts of the Mississippian and Pennsylvania sandstones in the center of the Michigan Basin. It is possible to simulate the direction of regional groundwater flow toward the Great Lakes and the center of the basin in the three aquifers that underlie the uplands in the north-central and south-central parts of the Lower Peninsula. Computer simulation showed that the proglacial Grand River flowed across the Lower Peninsula and created a topographic and water table depression. Model simulations inferred that these areas are likely to be groundwater discharge regions, because of the presence of saline groundwater near land surface in the lowlands. Steady-state simulations of regional groundwater flow suggest that the presence of saline groundwater in regional discharge areas result from the upwelling of deep saline groundwater within the regional groundwater flow system. (See also W90-08400) (Author's abstract)
RECORD ID: 9008404
F&G CODE: 02f
Publication
Mandle, R.J., and Westjohn, D.B., 1989, Geohydrologic framework and ground-water
flow in the Michigan basin, in Swain, L.A., and Johnson, A.I., eds., Regional
Aquifer Systems of the United States--Aquifers of the Midwestern Area: American
Water Resources Association Monograph Series 13, p. 83-109.
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