PREFACE


 This report was prepared by the Water Resources Division of
the U. S. Geological Survey in Cooperation with the Florida
Geological Survey, the Florida Division of Water Resources and
Conservation, and the Southwest Florida Water Management
District.
 The authors wish to express their appreciation for the
cooperation of the many residents and public officials for
information given during the well inventory and reconnaissance
of the area. Special acknowledgement is due the Florida State
Road Department, the Florida Forest Service, and property owners
who granted permission to drill test wells. The following agencies
made financial contributions for the collecting of data used in this
report: Hillsborough County, Marion County, Pasco County, Polk
County, Sumter County, Lake Apopka Recreation and Water
Conservation Control Authority, Oklawaha Basin Recreation and
Water Conservation and Control Authority, and Tsala Apopka
Basin Recreation and Water Conservation Control Authority.
 The calcium carbonate equilibrium study of ground water of
 central Florida was based on data collected and analysed in
 cooperation with William Back, Geologist, Water Resources
 Division, Arlington, Virginia, as part of an investigation of ground
 water along the Atlantic seaboard. Contributions to the knowledge
 of the geohydrology in the Withlacoochee-Hillsborough overflow
 area were made by Z. S. Altschuler, Geologist, Geologic Division,
 Washington, D. C. Assistance in the interpretation of electric and
 drillers' logs was rendered by C. R. Sproul, Geologist, Florida
 Geological Survey.
 The work on this project was done under the supervision of
 the Florida Water Resources Division Council comprised of A. O.
 Patterson, district engineer of the Branch of Surface Water, M. I.
 Rorabaugh, succeeded by C. S. Conover, district engineers of the
 Branch of Ground Water, and J. W. Geurin, district chemist,
 succeeded by K. A. MacKichan, district engineer, of the Branch of
 Quality of Water.