GROUND-WATER ISSUES
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.
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.
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:
Availability,
Point and nonpoint pollution, and
Natural water quality.
