The Ohio River alluvium is the best source of groundwater in the county. Many properly constructed drilled wells will produce several hundred gallons per minute from the alluvium. Most wells will produce enough for a domestic supply at depths less than 100 feet. Water is hard or very hard, but otherwise of good quality. In the lower sections of the larger creek valleys, most drilled wells shallower than 100 feet will meet domestic needs. Some wells located in the smaller creek valleys will produce enough water for a domestic supply except during dry weather. In the upland areas of Boone County (approximately 70 percent of the county), most drilled wells will not produce enough water for a dependable domestic supply; some wells along drainage lines may produce enough water, except during dry weather. Groundwater in these areas is hard or very hard and may contain salt or hydrogen sulfide, especially at depths greater than 100 feet.