This atlas is the product of an investigation of lakes and rivers in north central Florida, a cooperative effort by the St. Johns River Water Management District and the U.S. Geological Survey. The objectives of the study were to: 1.) identify evidence of breaches or discontinuities of the confining units between surficial water bodies and the Floridan aquifer, and; 2.) identify diagnostic features, structure and geomorphology of the lakes and rivers within the region.

The shallow subsurface of north central Florida is characterized as a mature karst (limestone) overlain by an overburden of clays, silts and sands that act as an impermeable layer between surficial waters and the Floridan aquifer. Breaches through this layer allow recharge or discharge of waters to or from the Floridan aquifer. The development of breaches are influenced by various physical parameters, including the thickness and lithologic composition of the overburden, the maturity of karst development and depth to the potentiometric surface of the aquifer. Knowledge of these parameters and identifying the location and magnitude of the breaches is important in understanding the interaction between the surface waters and the aquifer.