USGS

Altitude of Potentiometric Surface, Fall 1985, and Historic Water-Level Changes in the Fort Pillow Aquifer in Western Tennessee

U.S. Geological Survey, Water-Resources Investigations Report 89-4048

by W.S. Parks and J.K. Carmichael

This report is available as a pdf below


Abstract

Recharge to the Fort Pillow aquifer of Tertiary age is from precipitation on the outcrop, which forms a narrow belt across western Tennessee, and by downward infiltration of water from the overlying fluvial deposits of Tertiary(?) and Quaternary age and alluvium of Quaternary age or, where the upper confining unit is absent, from the overlying Memphis aquifer of Tertiary age. The potentiometric surface in the Fort Pillow aquifer slopes gently westward from the outcrop-recharge area, and the water moves slowly in that direction. A depression in the potentiometric surface in the Memphis area is the result of past pumping at Memphis Light, Gas and Water Division well fields (1924-74), past and present pumping at an industrial well field at Memphis, and the municipal well field at West Memphis, Ark. Withdrawals from the Fort Pillow aquifer in western Tennessee in 1985 averaged about 12 million gallons per day.

Water-level data from four observation wells, all in areas affected by pumping, indicate that water levels have declined at average rates ranging from about 0.4 to 0.9footperyearduring the past 40years (1945-85). The greatest rate of decline was as much as 4.0 feet per year between 1945 and 1954 in an observation well in a well field of Memphis Light, Gas and Water Division at Memphis. In 1971, Memphis Light, Gas and Water Division ceased pumping from the Fort Pillow aquifer at this well field, and between 1971 and 1976, water levels rose about 28 feet in this well.

Water levels in the Fort Pillow aquifer in large areas of western Tennessee away from the effects of pumping have fluctuated only in response to long-term variations in precipitation on the outcrop-recharge belt. Long-term changes in water levels in these areas have been small.

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U.S. Department of the Interior, U.S. Geological Survey
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