In the Kentucky River Valley, most drilled wells will produce enough water for a domestic supply at depths of less than 100 feet. In the larger creek valleys throughout the county, some wells will produce enough water for a domestic supply except during dry weather. In the upland areas of Estill County (70 percent of the county), most drilled wells will not produce enough water for a dependable domestic supply unless they are drilled along drainage lines, in which case they may produce enough water except during dry weather. Throughout the county, groundwater is hard or very hard and may contain salt or hydrogen sulfide, especially at depths greater than 100 feet. A few springs supply sufficient quantities of water for domestic use.