Reconnaissance of geohydrologic areas and 1981 low-flow conditions, Withlacoochee River basin, southwest Florida Water Management District

Abstract

The Withlacoochee River Basin of the Southwest Florida Water Management District is a management area of about 2,030 square miles in west-central Florida containing large reserves of potable ground water in the Upper Floridan aquifer. Results of reconnaissance test drilling indicate that the Upper Floridan aquifer may be treated as an unconfined aquifer in the management area which allows it to be divided into two types of geohydrologic areas: (1) areas of high recharge, and (2) areas of moderate recharge. Conceptually, the source of water to well fields in areas of high recharge would largely be natural recharge, whereas, in areas of moderate recharge, a significant part of the source of water to well fields would be induced downward leakage, or capture, of surface and near-surface water. The Withlacoochee River Basin of the Southwest Florida Water Management District is drained almost entirely by the Withlacoochee River and its tributaries. Field data were collected from April 13 through August 17, 1981, to document extremely low streamflow conditions. Conditions in the upper half of the drainage basin were found to be the most severe of record. On July 7, 1981, the total net runoff from the upper half of the basin was observed to be only 0.1 cubic foot per second. Low-flow conditions in the lower half of the drainage basin, however, were less severe than during the record low period of 1956. 1. Describe the mode of occurrence and quality of water in the Upper Floridan aquifer throughout the Basin.