Fresh water can be found in Cambrian and Ordovician carbonate rocks of the Knox Group in central Kentucky. The top of the aquifer is as much as 300 ft above mean sea level (m.s.l.) on the crest of the Cincinnati Arch, but descends off the flanks of the arch. Water is normally found in the upper 100 to 250 ft of the Knox, primarily in secondary porosity apparently associated with the unconformity at the top of the unit. Knox wells commonly exceed 750 ft in total depth, but because the aquifer is artesian, water rises to an elevation of about 500 ft above m.s.l. in most wells in central Kentucky. Some wells near the crest of the Cincinnati Arch produce water with relatively low concentrations of dissolved solids (500 to 3,000 milligrams per liter [mg/L]). Concentrations of dissolved solids commonly exceed 10,000 mg/L away from the crest of the arch. The Knox aquifer provides modest quantities of water (normally on the order of 10 to 20 gallons per minute) with less than 1,000 mg/L of dissolved solids to several wells in the Inner Blue Grass Region. As a result, it is a potential source of water for rural domestic supplies in central Kentucky.
Report of Investigations 12
Digital Object Identifier (DOI)
Kipp, James A., "Fresh-Water Aquifer in the Knox Group (Cambrian–Ordovician) of Central Kentucky" (1997). Kentucky Geological Survey Report of Investigations. 52.