Ground water is obtained mostly from limestone and dolomite aquifers along the Sequatchie anticline and Murphrees Valley anticline and. from sandstone aquifers in Sand Mountain and Blount Mountain synclinal areas. Wells tapping some limestone and dolomite aquifers produce as much as 1.4 mgd (million gallons per day). Wells completed in sandstone of the Pottsville Formation underlying lower topographic areas may produce as much as 0.3 mgd, but those completed in sandstone underlying higher topographic areas produce lesser quantities.
Surface-water resources were appraised by use of average flow and 7-day Q2 (median annual 7-day minimum flow).An average flow of about 640 mgd or about 1 mgd per square mile originates in the county. Streamflow during low flow conditions is small; only three streams have 7-day Q2's that exceed 2 mgd. Estimates of storage requirements are provided for sustained draft rates of 25 to 50 percent of the average flow.
Water from aquifers and streams in Blount County is generally of suitable chemical quality for most uses. Water from the Pottsville Formation generally contains iron in excess of 0.3 mg/l (milligrams per liter) and water from limestone and dolomite aquifers and from some streams during low flows is moderately hard to hard and may need treatment for certain uses.
Water use in the county was about 3.2 mgd in 1968 and 46 mgd was diverted for use outside the county.