Ground-water resources and geology of Washington and Ozaukee Counties, Wisconsin

Population growth is placing increased demands on water supplies in Washington and Ozaukee Counties. Water from three principal aquifers supplies most municipal, industrial, irrigation, residential, and farm water needs in these counties. These are the sand-and-gravel, Niagara, and sandstone aquifers. As much as 15 gallons per minute can be obtained from wells almost everywhere in these counties. Yields of 500 to 1,000 gallons per minute are available from the sand-and-gravel aquifer in parts of Washington County. The Niagara aquifer underlies most of the area and can yield as much as 500 gallons per minute in most of Ozaukee and eastern Washington Counties. It yields less than 100 gallons per minute in some areas, notably eastern Mequon in Ozaukee County and parts of western Washington County. The sandstone aquifer underlies the entire area and generally can yield more than 1,000 gallons per minute to wells. However, yields of less than 500 gallons per minute are common in southwestern Washington County, where the aquifer is thinnest.