Kansas Geological Survey, Public Information Circular (PIC) 7
Prev. Page--Well Yields
Kansas Geological Survey, Public Information Circular (PIC) 7
Prev. Page--Well Yields
Ground-water availability and levels of salinity in the Dakota aquifer are highly variable because of the different sources of fresh and saltwater recharge to the aquifer and the flow of ground water through the aquifer system. In general, the Dakota is a good source of freshwater where the aquifer is encountered at shallow depths in southwestern, west-central, and central Kansas. In these areas, the aquifer is closer to sources of freshwater recharge and most of the salinity has been removed by the flow of ground water acting over millions of years.
The aquifer is suitable for most uses throughout its extent in Kansas except for areas of high salinity in the northwest and north-central parts of the state. The major limitations on its use depend on the cost of producing the water, aquifer thickness, and the necessity of additional treatment to remove salinity.
The cost of producing water from the Dakota is directly related to factors that include the energy and other costs associated with well installation and pumping. These factors are significant in determining whether taking water from the Dakota is economical, particularly where the depth to the top of the Dakota exceeds 1,000 feet (305 m) near the northwest corner of the state.
Well yields in the Dakota are generally not as great as in the High Plains aquifer. As a result, the Dakota should not be considered a replacement source of water for the High Plains aquifer. Nevertheless, if it is managed properly, the Dakota will be an important source of water for Kansans in the future.
Additional information on the Dakota aquifer can be obtained by contacting the Geohydrology Section at the Kansas Geological Survey (785-864-3965; 785-864-7728, FAX). The Kansas Geological Survey also maintains a World Wide Web home page that features information on the Dakota aquifer.
Further information on the topics covered in this pamphlet can be found in the following publications.
Buchanan, R. C., and Buddemeier, R. W., compilers, 1993, Kansas Ground Water: Kansas Geological Survey, Educational Series 10.
Macfarlane, P. A., 1995, The Effect of River Valleys and the Upper Cretaceous Aquitard on Regional flow in the Dakota aquifer in the Central Great Plains of Kansas and Southeastern Colorado; in, Current Research on Kansas Geology, Kansas Geological Survey, Bulletin 238.
Macfarlane, P. A., and Sawin, R. S., 1996, A User's Guide to Well-spacing Requirements for the Dakota Aquifer in Kansas: Kansas Geological Survey, Public Information Circular 1.
U.S. Bureau of Mines, 1995, Minerals Yearbook, Area Reports--Domestic 1993-94, v. 2: Washington, D.C., U.S. Government Printing Office, p. 97-101.
Aquifer: A part of a geologic formation, or one or more geologic formations, that is porous and permeable enough to transmit water at a rate sufficient to feed a spring or for economic extraction by a well. An aquifer transmits more water than an aquitard.
Aquitard: A part of a geologic formation, or one or more geologic formations, that is of much lower permeability than an aquifer and will not transmit water at a rate sufficient to feed a spring or for economic extraction by a well.
Confined aquifer: An aquifer that is bounded above and below by aquitard units; water levels in wells screened in a confined aquifer are higher than the top of the aquifer.
Discharge area: An area where ground water is lost naturally from an aquifer through springs, seeps, or hydraulic connection to other aquifers. The water leaving the aquifer is referred to as discharge.
Hydraulically connected: A condition in which ground water moves easily between aquifers that are in direct contact. An indication of this condition is that the water levels in both aquifers are approximately equal.
Permeability: A measure of the ease with which water will move through an aquifer or an aquitard. A geologic unit is permeable if ground water moves easily through it.
Recharge area: A geographic area where water enters (recharges) an aquifer. Recharge areas usually coincide with topographically elevated regions where aquifer units crop out at the surface. In these areas infiltrated precipitation is the primary source of recharge. The recharge area may also coincide with the area of hydraulic connection where one aquifer receives flow from another adjacent aquifer.
Salinity: The sum of the dissolved materials in water expressed in milligrams/liter (mg/L). The upper limit for freshwater is 1,000 mg/L; natural seawater has a salinity of approximately 35,000 mg/L.
Unconfined aquifer: An aquifer that is not bounded above by an aquitard; water levels in wells screened in an unconfined aquifer coincide with the elevation of the water table.
Kansas Geological Survey, Public Outreach
bsawin@kgs.ku.edu
Web version April 1997
http://www.kgs.ku.edu/Publications/pic7/pic7_3.html