Groundwater Availability
 

Alluvium (Qa)
Topography
The alluvium forms broad, flat areas in the Salt River Valley and larger tributaries. Flats are dissected by short, steep-sided gullies near tributaries.

Hydrology
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 Formation (Ob)
Topography
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 streams.

Hydrology
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 (Oaf)
Topography
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.

Hydrology
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 hydrogen sulfide.

Clays Ferry Formation (Okc) and Kope Formation (Ok)
Topography
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.

Hydrology
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 sulfide.

Lexington Limestone (Ol)
Topography
The Lexington has no surface exposure in Spencer County, but underlies the entire area.

Hydrology
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)
Topography
The High Bridge has no surface exposure in Spencer County, but underlies the entire area.

Hydrology
The High Bridge is not likely to yield water of suitable quality. It is not considered an aquifer in this area.

Knox Group (Okx)
Topography
The Knox has no surface exposure in Kentucky, but underlies the entire state at varying depths.

Hydrology
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 County.

You can find out more about the Knox aquifer.

The U.S. Geological Survey's Hydrologic Atlas Series, published cooperatively with the Kentucky Geological Survey, provides hydrologic information for the entire state.

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