Public Water-Supply Systems and Associated Water Use in Tennessee, 1995

Table 2. Aquifer and well characteristics in Tennessee (modified from Hollyday and Bradley, 1985) 

[ft, foot; gal/min, gallon per minute]

Aquifer name and description1                       Well characteristics                                                 Remarks
                                           Depth (ft)                           Yield (gal/min)
                                  _______________________________    ________________________________
                                   Common range        May exceed     Common range         May exceed

Alluvial: Sand, gravel,             10 - 75               100           20 - 50               1,500            High iron concentrations
  and clay. Unconfined.                                                                                          in some areas.

Tertiary sand: Multi-aquifer       100 - 1,300          1,500          200 - 1,000            2,000            Includes Memphis Sand of
  unit of sand, clay, silt,                                                                                      Claiborne Group and
  and some gravel and lignite.                                                                                   Fort Pillow Sand of
  Confined; unconfined                                                                                           Wilcox Group. Problems
  in the outcrop area.                                                                                           with high iron concen-
                                                                                                                 trations in some places.

Cretaceous sand: Multi-aquifer     100 - 1,500          2,500           50 - 500              1,000            Includes McNairy and 
  unit of interbedded sand,                                                                                      Coffee Sands, and 
  clay, marl, and gravel.                                                                                        Tuscaloosa Formation.
  Confined; unconfined                                                                                           Water withdrawn 
  in the outcrop area.                                                                                           primary in the outcrop

Pennsylvanian sandstone: Multi-    100 - 200              250            5 - 50                 200            Permeability is from
  aquifer unit, primarily                                                                                        fractures, faults, and
  sandstone and conglomerate,                                                                                    bedding-plane openings.
  interbedded shale and some                                                                                     Principal water-bearing
  coal. Unconfined near land                                                                                     units are Rockcastle  
  surface; confined at depth.                                                                                    and Sewanee Conglomerates.
                                                                                                                 High iron concentrations 
                                                                                                                 are a problem.

Mississippian carbonate rock:       50 - 200              250            5 - 50                 400            Water occurs in solution and
  Multi-aquifer unit of                                                                                          bedding-plane openings.
  limestone, dolomite, and                                                                                       Principal water-bearing 
  some shale. Unconfined or                                                                                      units are Ste.Genevieve
  partly confined near land                                                                                      (Monteagle), St. Louis
  surface; may be confined                                                                                       and Warsaw Limestones and
  at depth.                                                                                                      Fort Payne Formation. 
                                                                                                                 Water generally hard; 
                                                                                                                 high iron, sulfide, or 
                                                                                                                 sulfate concentrations 
                                                                                                                 are a problem in some 

Ordovician carbonate rock:          50 - 150              200            5 - 20                 300            Principal water-bearing 
  Multi-aquifer unit of                                                                                          units are Bigby, Carters,
  limestone, dolomite, and                                                                                       Ridley, and Murfreesboro
  shale. Partly confined to                                                                                      Limestones. Water gen-
  unconfined near land surface;                                                                                  erally hard; some high
  confined at depth.                                                                                             sulfide or sulfate 
                                                                                                                 concentrations in places.

Knox: Primarily dolomite, some     700 - 1,200          1,400            1 - 10                  20            Deep aquifer; occurs under
  limestone; confined. Does not                                                                                  most of central and
  have the structural complexity                                                                                 western Tennessee. Away
  of the Cambrian-Ordovician                                                                                     from Central Basin, water
  carbonate aquifer.                                                                                             generally has high 
                                                                                                                 concentrations of 
                                                                                                                 dissolved solids.
Cambrian-Ordovician carbonate      100 - 300              400            5 - 200              2,000            Principal water-bearing 
  rock: Extremely faulted multi-                                                                                 units are carbonate rocks
  aquifer unit of limestone,                                                                                     in Chickamauga Limestone,
  dolomite, sandstone, and                                                                                       Knox Group, and Honaker
  shale; structurally complex.                                                                                   Dolomite. Water is 
  Unconfined; confined at depth.                                                                                 generally hard. Brine is
                                                                                                                 present below 3,000 feet.
Crystalline rock: Multi-aquifer     50 - 150              200            5 - 50               1,000            High yields occur primarily
  unit of dolomite, granite                                                                                       in dolomite or deep
  gneiss, phyllite, and                                                                                           colluvium and alluvium.
  metasedimentary rocks                                                                                           Shady Dolomite is a 
  overlain by thick regolith;                                                                                     principal aquifer. Low pH
  alluvium and colluvium                                                                                          and high iron concentra-
  in some valleys. Generally                                                                                      tions may be problems in
  unconfined.                                                                                                     some areas.

1Refer to figure 1 for location map.
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