Nomenclature Issues in Aquifer Systems with Varying Connectivity Between Surficial and Regional Confined Aquifer Systems

Formal naming of aquifers that contain varying hydraulic connections to overlying unconfined and underlying confined regional aquifer systems is laden with great difficulty. Commonly, aquifers or aquifer systems are clearly divided by regional confining units that separate them sufficiently to allow formal definition and naming of correlative hydraulic units. However, in mixed siliciclastic and carbonate sediments of southwest Florida, the distal to proximal pinching out of confining units creates a series of discontinuous, sub-regional aquifers than can have direct hydraulic connections to either the unconfined Surficial Aquifer System or the underlying Floridan Aquifer System. Current nomenclature places this complex system of sub-regional aquifers into the “Intermediate Aquifer System.” A given aquifer may be present over an area of between 500 and 1000 square kilometers. A given hydraulic unit within this complex may pinch-out down-dip, merge with another aquifer, or combine hydraulically with the underlying Floridan Aquifer System. There are at least six different names applied to various geographic areas of the Intermediate Aquifer System (e.g. Sandstone Aquifer in Lee County, zones A to C in Sarasota County, etc.). It is suggested that the aquifer nomenclature be defined consistently with the predominant hydraulic connection that most influences the potentiometric surface and water quality found within the local aquifer.