The alluvium forms broad, flat areas in the Salt River Valley and larger
tributaries. Flats are dissected by short, steep-sided gullies near
The alluvium yields 100 to 500 gallons per day to wells, and may yield more
than 500 gallons per day where
gravel is present. Water is hard.
Drakes Formation (Saluda Dolomite, Bardstown, Rowland Members) (Od)
and Bull Fork
These formations provide moderately dissected upland areas, with moderately
steep slopes where shale predominates and less-steep slopes where limestone
predominates. The Drakes and Bull Fork Formations create steep slopes
along large streams and cliffs, many dotted with weathered limestone
slabs. Solutional features are evident where thick limestone beds underlie
These formations yield 100 to 500 gallons per day to wells in large
stream valleys, and more where thick limestone is present. They yield
almost no water to wells on hillsides and ridges, except in broad ridges
in the upper part of the formation. They do yield water to small springs.
Water is hard and may contain salt in valley bottoms but is generally
of good quality.
Grant Lake Limestone, Fairview Formation, Calloway Creek Limestone
These formations create gently to moderately rolling uplands away from
major streams. They are more highly dissected where shale content increases,
and have small sinkholes, minor underground drainage, and broad, flat
valleys where limestone predominates. The lower part forms broad, flat
ridges between steep-sided valleys cut into underlying shale of the
Kope or Clays Ferry Formations.
These formations yield 100 to 500 gallons per day to drilled wells in
broad valleys and along streams in uplands. More than 500 gallons per
day is yielded from thick limestone beds in the broad valley bottoms,
but almost no water to drilled wells on hillsides or ridgetops. These
formations do yield water to small springs and seeps. A limestone bed
15 feet thick in the lower part of the Grant Lake yields as much as
30 gallons per minute to springs. The sandy zone near the base yields
little water. Water is hard and in valley bottoms may contain salt or
Clays Ferry Formation (Okc) and Kope Formation (Ok)
These formations create rugged topography of narrow, steep-sided ridges
with narrow V-shaped valleys of dendritic drainage. Shales on steep
slopes erode easily and are covered with thin limestone slabs in many
places. The contrast with the less-rugged surface of the adjacent areas
is marked except near major streams. In the lower part of the formation,
upland topography becomes more gently to moderately rolling, with small
sinkholes and some underground drainage where limestone predominates.
These formations yields 100 to 500 gallons per day to drilled wells
in large valley bottoms along streams, but almost no water to drilled
wells on hillsides or ridgetops. They do yield water to small springs
and seeps. Water is hard in valley bottoms may contain salt or hydrogen
Lexington Limestone (Ol)
The Lexington has no surface exposure in Spencer County, but underlies
the entire area.
The Lexington is not likely to yield usable amounts for any purpose.
It is not considered an aquifer in this area.
High Bridge Group (Ohb)
The High Bridge has no surface exposure in Spencer County, but underlies
the entire area.
The High Bridge is not likely to yield water of suitable quality. It
is not considered an aquifer in this area.
Knox Group (Okx)
The Knox has no surface exposure in Kentucky, but underlies the entire
state at varying depths.
In central Kentucky, fresh water has been found in the upper 100 to
250 feet of this largely untested dolomite-rich aquifer. Wells often
exceed 750 feet in total depth, and have high concentrations of dissolved
solids in many areas. Average reported yields range in the 10 to 20
gallon per minute range but can be as high as 75 gallons per minute.
The Knox is not likely to yield water of suitable quality in Spencer
You can find out more about the Knox
The U.S. Geological Survey's Hydrologic
Atlas Series, published cooperatively with the Kentucky Geological
Survey, provides hydrologic information for the entire state.
to "Groundwater Resources in Kentucky"