The increasing need for water of good Quality in Columbia County, caused by a steadily increasing population, can be met from the sand-and-gravel and sandstone aquifers. As much as 15 gallons per minute can be obtained from wells almost everywhere. Yields of more than 1,000 gallons per minute are available from drift where it contains a sufficient thickness of saturated sand and gravel (the sand-and-gravel aquifer). The sandstone aquifer underlies nearly all the county except for areas west of the Wisconsin River and northwest of Pardeeville. It is more than 700 feet thick in the south-central part. The sandstone aquifer includes all bedrock younger than Precambrian age and is capable of yielding more than 1,000 gallons per minute to wells in about three-fourths of the county. It is the principal source of municipal-water supply.

The chemical quality of water from the two aquifers is similar. It is very hard (mean concentration of about 300 milligrams per liter as calcium carbonate), and much of it contains excessive amounts of iron and manganese. Concentrations of dissolved solids and chloride are higher in areas underlain by bedrock of Ordovician age than elsewhere.

About 5.0 million gallons per day of water was pumped in the county in 1974, 90 percent from the sandstone aQuifer. About 45 percent of the total water pumped was for industrial and commercial purposes~ 37 percent was for residential use, 16 percent for municipal use, and 2 percent for irrigation.