U.S. Geological Survey Open-File Report 03-47 by Ank Webbers
This report also is available as a pdf (1.7 MB).
Ground water provided about 321 million gallons per day (Mgal/d) of public water supplies in Tennessee during 2000. A total of 256 public water-supply systems provided these supplies to 72 of Tennessee's 95 counties. Ground water provided approximately 36 percent of the total public water supplies used in Tennessee.
The U.S. Geological Survey, in cooperation with the Tennessee Department of Environment and Conservation (TDEC), Division of W ater Supply, has prepared several reports on ground-water use by public water-supply systems in Tennessee (Hutson, 1989, 1991, 1995, and 1998). This report, prepared in cooperation with TDEC, presents ground-water withdrawals by public water-supply systems in Tennessee for 2000 and provides a brief discussion on reported values of ground-water use in Tennessee during previous years.
A total of 256 public water-supply systems provided ground water for drinking water and other purposes to residents in 72 of the 95 Tennessee counties in 2000 (fig. 1). A total of 117 public water-supply systems were located in West Tennessee, 46 systems were located in Middle Tennessee, and 93 systems were located in East Tennessee. Sixty of the 257 systems produced less than 0.02 million gallons per day (Mgal/d). Thirty-eight public water-supply systems withdrew 1 Mgal/d or more of ground water during 2000. Memphis Light, Gas and Water, a public water-supply system located in Shelby County (West Tennessee) reported the largest ground-water withdrawal (about 167 Mgal/d) for a single system. Public water-supply systems in Tennessee reporting ground-water withdrawals of at least 0.02 Mgal/d in 2000 are listed in table 1 with the withdrawal rate, ground-water source (well or spring), principal aquifer, and whether the ground-water supply is supplemented with surface water or purchased water.
Ground water provided 36 percent of Tennessee's public water supplies in 2000 (fig. 2). Ground water was withdrawn from drilled wells and natural springs that flow from aquifer outcrops or exposed rock fractures at land surface. The principal aquifers in Tennessee (fig. 3) are the alluvial aquifer, Tertiary sand aquifers, Cretaceous sand aquifer, Mississippian carbonate aquifer, Ordovician carbonate aquifer, Pennsylvanian sandstone aquifer, Cambrian-Ordovician carbonate aquifer, and crystalline rock aquifer (Bradley and Hollyday, 1985). The Knox aquifer in Middle Tennessee is not currently being used for public water supply because of the aquifer depth and typically high sulfate concentrations, but it is used locally for domestic water supplies (Brahana and Bradley, 1985). Ground-water withdrawals from the principal aquifers during 2000 ranged from less than 1 Mgal/d (0.1 percent) from the Pennsylvanian sandstone aquifer to 188 Mgal/d (about 58 percent) from the Memphis aquifer of the Tertiary sand aquifers (figs. 3 and 4).
In West Tennessee, ground-water supplies are produced from the thick (greater than 2,500 feet) sequence of unconsolidated sands, gravels, and clays of Quaternary alluvium deposits, the Tertiary sand aquifer that includes the Cockfield and Cook Mountain Formations, the Memphis Sand, and the Fort Pillow Sand. The Cretaceous sand aquifer includes the McNairy Sand, Coffee Sand, and Eutaw, Tuscaloosa, and Ripley Formations. To better define ground-water use in West Tennessee and because of their regional importance, the major aquifers in the Tertiary sand aquifers, the Memphis aquifer, and the Fort Pillow aquifer are identified where possible.
Approximately 244 Mgal/d were produced from the Tertiary sand aquifers in 15 counties of West Tennessee in 2000. This quantity represents approximately 75 percent of the total public supply ground-water withdrawals from all aquifers in the State (fig. 4). The combined ground-water withdrawal from the Memphis aquifer and the Fort Pillow aquifer was approximately 192 Mgal/d (fig. 4) with the Memphis aquifer supplying approximately 188 Mgal/d. The Cretaceous and the Quaternary (alluvial deposits) aquifer systems in 2000 provided ground-water supplies of approximately 11 and 2 Mgal/d, respectively (figs. 3 and 4). The largest ground-water withdrawals occurred in Shelby County (188 Mgal/d) and Madison County (15 Mgal/d) from the Tertiary sand aquifer (table 1).
Ground-water withdrawals in Middle and East Tennessee are primarily from natural springs or from wells drilled into Precambrian-, Cambrian-, Ordovician-, Mississippian-, and Pennsylvanian-age rocks. In 2000, public water-supply systems in these two sections of the State withdrew about 63 Mgal/d.
In Middle Tennessee, ground water generally is withdrawn from solution cavities of the Ordovician and Mississippian carbonate aquifers. Well depths commonly range from less than 50 to about 200 feet. Well yields generally vary from about 5 gal/min to greater than 50 gal/min and may exceed 400 gal/min in some areas (Bradley and Hollyday, 1985). During 2000, aquifers in Middle Tennessee supplied 21 counties with approximately 21 Mgal/d. The average ground-water withdrawal for 48 public water-supply systems in Middle T ennessee was less than 1 Mgal/d (0.31 Mgal/d). The largest ground-water withdrawal (4.42 Mgal/d) by one water system in Middle Tennessee occurred in Montgomery County.
In East Tennessee, ground water is present in interconnected fractures and openings of the Pennsylvanian sandstone aquifer of the Cumberland Plateau, in fractures and solution openings in the Cambrian-Ordovician carbonate aquifer and in the fractured crystalline rock aquifer. The Cambrian-Ordovician carbonate aquifer also can be extensively faulted or structurally deformed.
Drilled wells range from less than 50 to 350 feet deep (Brahana, Macy, and others, 1986), and well yields ranged from 5 gal/min to about 50 gal/min in the Pennsylvanian sandstone and crystalline rock aquifers, and to about 200 gal/min in the Cambrian-Ordovician carbonate aquifer. Wells completed in large interconnected solution openings of the Cambrian-Ordovician carbonate aquifer may yield more than 2,000 gal/min (Bradley and Hollyday, 1985). The aquifer systems of East Tennessee supplied approximately 44 Mgal/d of ground water to 93 public water-supply systems in 31 counties. The highest ground-water withdrawals for public supply were in Hamilton County, 10.44 Mgal/d, and Carter County, 7.52 Mgal/d (fig. 1).
Springs were used as water sources by 46 public water-supply systems in 28 counties of Middle and East Tennessee during 2000 (fig. 1). The springs provided about 40 Mgal/d, approximately 12 percent of the total ground-water withdrawals for Tennessee in 2000 (fig. 2). Most of the spring use by public water-supply systems was in East Tennessee where about 27 Mgal/d were produced from the Cambrian-Ordovician carbonate aquifer. The largest use of spring water for public water supply, by county, occurred in Montgomery County (4.42 Mgal/d), Carter County (6.29 Mgal/d), Washington County (3.72 Mgal/d), and Bradley County (2.56 Mgal/d).
The population of Tennessee increased from 3.29 million in 1950 to 5.68 million in 2000 (U.S. Census Bureau, 2002). In 1950, ground-water withdrawals for public water supply in Tennessee were 85 Mgal/d (MacKichan, 1957), and by 1980 withdrawals had reached 210 Mgal/d (fig. 5). From 1985 to 1988, ground-water withdrawals by public water-supply systems increased from 243 to 262 Mgal/d (Hutson, 1990; Hutson and Morris, 1992), and by 1995 withdrawals reached 279 Mgal/d (Hutson, 1999). However, the ratio of ground water to surface water use by public systems had begun to decrease slightly in 1985, and in 2000, ground water provided only 36 percent of public water supplies in Tennessee.
The number of public water-supply systems providing ground water in the State has also increased from 181 systems in 1985 (Hutson, 1989) to 256 systems in 2000. In addition, the data for 2000 indicate more public water-supply systems used ground water (256 systems) than surface water (142 systems) as their primary source of water. The use of ground water by public water-supply systems as a primary source is mainly in West Tennessee where ground-water withdrawals have increased approximately 40 percent, from about 185 Mgal/d in 1985 to 257 Mgal/d in 2000. In Middle and East Tennessee public water-supply systems supplement customer demands with surface water or may not use ground water.
Bradley, M.W., and Hollyday, E.F., 1985, Tennessee ground-water resources, in National Water Summary 1984—Hydrologic events, selected water-quality trends, and ground-water resources: U.S. Geological Survey Water-Supply Paper 2275, p. 391-396.
Brahana, J.V., and Bradley, M.W., 1985, Delineation and description of the regional aquifers of Tennessee—the Knox aquifer in Central and West Tennessee: U.S. Geological Survey Water-Resources Investigations Report 83-4012, 32 p.
Brahana, J.V., Macy, J.A., Mulderink, Dolores, and Zemo, Dawn, 1986, Preliminary delineation and description of the regional aquifers of Tennessee—Cumberland Plateau aquifer system: U.S. Geological Survey Water-Resources Investigations Report 82-338, 24 p.
Brahana, J.V., Mulderink, Dolores, Macy, J.A., and Bradley, M.W., 1986, Preliminary delineation and description of the regional aquifers of Tennessee—The East Tennessee aquifer system: U.S. Geological Survey Water-Resources Investigations Report 82-4091, 30 p.
Hutson, S.S., 1989, Ground-water use by public-supply systems in Tennessee in 1985: U.S. Geological Survey Water-Resources Investigations Report 89-4092, 1 sheet.
Hutson, S.S., 1990, Tennessee water supply and use, in National Water Summary 1987—Hydrologic events and water supply and use: U.S. Geological Survey Water-Supply Paper 2350, p. 467-474.
Hutson, S.S., 1991, Ground-water use by public-supply systems in Tennessee in 1988: U.S. Geological Survey Open-File Report 91-176, 1 sheet.
Hutson, S.S., 1995, Ground-water use by public-supply systems in Tennessee, 1990: U.S. Geological Survey Water-Resources Investigations Report 94-483, 1 sheet.
Hutson, S.S., 1998, Ground-water use by public-supply systems in Tennessee, 1995: U.S. Geological Survey Open-File Report 98-85, 1 sheet.
Hutson, S.S., 1999, Public water-supply systems and associated water use in Tennessee, 1995: U.S. Geological Survey Water-Resources Investigations Report 99-4052, 91 p .
Hutson, S.S., and Morris, A.J., 1992, Public water-supply systems and water use in Tennessee, 1988: U.S. Geological Survey Water-Resources Investigations Report 91-4195, 74 p .
MacKichan, K.A., 1957, Estimated use of water in the United States, 1955: U.S. Geological Survey Circular 398, 18 p .
U.S. Census Bureau, 2002, State and county quickfacts—Tennessee, accessed August 9, 2002 at http://quickfacts.census.gov/qfd/states/47000.html
___________________________________________________________________________________
Multiply By To obtain
___________________________________________________________________________________
gallon (gal) 3.785 liter (L)
gallon (gal) 0.003785 cubic meter (m3)
million gallons (Mgal) 3,785 cubic meter (m3)
cubic foot (ft3) 0.02832 cubic meter (m3)
acre-foot (acre-ft) 1,233 cubic meter (m3) gallon per minute (gal/min) 0.06309 liter per second (L/s) ___________________________________________________________________________________
Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27).