Robert J. Faust | USGS Science

USGS1975

Geology and water availability of Cullman County, Alabama

The Pottsville Formation of Pennsylvanian age underlies most of Cullaman County in northern Alabama. It consists mostly of interbedded sandstones and shales that dip southward about 40 feet per mile. The Bangor Limestone of Mississippian age underlies the Pottsville and crops out in a few valleys along the northern boundary of the county. The principal source of ground water in the county is the Pottsville Formation. Sandstones of the Pottsville Formation underlying low topographic areas will yield as Much as 200 gpm (gallons per minute) to individual wells 200 feet deep or less in the southeastern part of the the county and 25-100 gpm in other parts. Those underlying high topographic areas generally yield less than 5 gpm. The average flow of streams in and adjoining Cullman County is about 1,500 mgd (million gallons per day) which includes about 780 mgd that originates in the county. Discharge from ground-water storage is small, and most streams cease to flow during extended dry periods. Sipsey Fork and Mulberry Fork are the only streams in and adjoining Cullman County that have median annual 7-day low flows that exceed 2 mgd.

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USGS1975

Water availability of Blount County, Alabama

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.

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