J. H. Green 1988 <p>GROUND-WATER ISSUES<br /> Ground-water sources provide about one-half of the water used in Wisconsin, excluding the water used for thermoelectric cooling. Ground-water sources serve about 70 percent of the State's population. All rural-domestic supplies and about 94 percent of the municipalities use ground water. Nearly all irrigation and stock watering are from ground water.</p> <p>Aquifers in Wisconsin are grouped into three principal types the sandstone aquifer, the Silurian-dolomite aquifer, and the sand-and-gravel aquifer. The sandstone aquifer underlies the southern two-thirds of the State and includes numerous rock formations, mostly sandstone and dolomite. Water in this aquifer usually is very hard. The Silurian-dolomite aquifer is found only along the area near Lake Michigan where it underlies the sandandgravel aquifer. Ground water in the Silurian-dolomite aquifer is the hardest of all ground water in Wisconsin and usually can benefit from softening. The sand-and-gravel aquifer is mostly permeable unconsolidated sediments in stream-valley alluvium and glacial deposits. The glacial deposits cover much of the State's land surface. Water from the sand-and-gravel aquifer is acceptable for nearly all uses.</p> <p>Changes in land and water use have caused increasing concerns about water supplies, water quality, water-related environmental conditions, and water management. The major ground-water issues in the State are related to:</p> <p>Availability,</p> <p>Point and nonpoint pollution, and</p> <p>Natural water quality.</p> application/pdf 10.3133/ofr88138 en U.S. Geological Survey, U.S. Geological Survey ground-water studies in Wisconsin reports