Ground-water resources and geology of Colquitt County, Georgia

Abstract

Limestone beds of Eocene, Oligocene, and lower Miocene age, called the principal artesian aquifer, are the chief source of ground water for Colquitt County. Because streams are small, undependable and relatively inaccessible to most users, ground water is the most important source for increased industrial and agricultural water use. INTRODUCTION Colquitt County, Ga., largely depends on ground water for domestic and industrial use. Water-well drillers, however, have experienced difficulty in obtaining adequate supplies in some parts of the county. The drillers noted anomalous groundwater heads and water-quality problems. Studies in other counties in southwestern Georgia suggested that these anomalies might be related to poorly defined structural features. These were among the reasons that Colquitt County was selected for study in 1967. Location and Extent of the Area Colquitt County (fig. 1) includes an area of 536 mil (1,458 km 2) in south-central Georgia. The county lies in the lower Coastal Plain physiographic province. The principal towns include the county seat, Moultrie (1970 population, 14,302); Doerun (1,157); Norman Park (912); Berlin (422); Ellenton (337); Funston (293); and Crosland (158). Colquitt County is bordered on the north by Worth and Tift Counties, on the east by Cook County, on the south by Brooks and Thomas Counties, and on the west by Mitchell County. FIGURE I.-LOCATION OF COLOUITT COUNTY Purpose and Scope of the Investigation Although surface water is still the main source of irrigation water, ground water is the principal source of domestic, industrial, and stock water in Colquitt County. Responsible governmental and service organizations in Colquitt County hope for and expect continued economic expansion in industry and agriculture. This expansion will almost certainly be accompanied by a greatly increased demand for water. The only source likely to meet this demand is ground water. It is necessary to evaluate the magnitude of this resource in order to properly plan for continued development. To aid in this evaluation, the Georgia Department of Natural Resources, Geologic and Water Resources Division, maintains a statewide cooperative program with the U.S. Geological Survey to appraise Georgia's water resources. The objectives of this investigation were: 1. To map and study the subsurface formations that constitute the principal artesian aquifer and its water-bearing zones, and to determine their hydrologic properties. 2. To map and study the beds making up lesser aquifer systems and to determine their hydrologic properties. 3. To determine geologic structure and its hydrologic significance. 4. To determine the sustained yield of wells and the quality of the water available in the various aquifer systems. Previous Investigations Colquitt County, as a part of the Coastal Plain of Georgia, has been discussed in a number of reports covering south Georgia or the Southeast. These include, "Artesian water in Tertiary limestone in the southeastern States" (Stringfield, 1966) and "Subsurface geol...

Hydrologic and water-quality conditions in the lower Apalachicola-Chattahoochee-Flint and parts of the Aucilla-Suwannee-Ochlockonee River basins in Georgia and adjacent parts of Florida and Alabama during drought conditions, July 2011

“…The study area contains all or parts of 10 hydrologic unit code (HUC) subbasins in the lower ACF River basin (HUCs beginning with 0313) (Seaber and others, 1987;Jones and Torak, 2006) and all or parts of five HUC subbasins in the western and central ASO River basin (HUCs beginning with 0311 and 0312). The study area extends through the Gulf Trough-Apalachicola Embayment, a northeast-southwest trending geologic feature composed of fine-grained, dense, low-permeability limestone overlain by a thick sequence of Oligocene to Miocene sediments (Zimmerman, 1977). The juxtaposition of low-permeability sediments of the Gulf Trough-Apalachicola Embayment and the high-permeability limestone forms a barrier to groundwater flow southeastward in the Upper Floridan aquifer (Torak, and others, 2010.…”

Geohydrology of the Aucilla-Suwannee-Ochlockonee River Basin, south-central Georgia and adjacent parts of Florida

“…Figure 7. Geologic sections across northeastern Florida showing relations between geologic units and the Floridan aquifer system along A-A', from west of Lake City, Florida, to the Atlantic Ocean; and B-B', from Duval County, Florida, to Fernandina Beach, Florida (modified from Leve, 1968 Zimmerman, 1977). The Ocala "Uplift," a comparatively younger structure than the Peninsular Arch ( fig.…”

“…9). The principal hypotheses for the origin of the Gulf Trough have been summarized by Patterson and Herrick (1971) and listed by Zimmerman (1977). These hypotheses are that the Gulf Trough defines (1) a buried submarine valley or strait analogous to the Straits of Florida;…”

“…Miller (1986) described a process where low-permeability clastic sediments fill grabens in the fault zone and are juxtaposed with high-permeability limestone units in the Floridan aquifer system. Zimmerman (1977) described the pinch-out of highpermeability Upper Eocene fossiliferous limestone along the trend of the Gulf Trough and deposition of low-permeability Oligocene dolomitic limestone and marl in its place ( fig. 8).…”

“…9); however, Sever (1965) described equivalent geologic units of the Alum Bluff Group as the "Hawthorne Formation." Hawthorn Group sediments range in thickness from a featheredge in northwestern Colquitt County to about 300 ft in or near the Gulf Trough-Apalachicola Embayment (Zimmerman, 1977). The "Hawthorne Formation" thickens to 500 ft in Ware County, where very sticky, cohesive, greenish-blue clay in the upper part of the formation confines sandy and phosphatic dolomite and limestone of the middle and lower parts, in addition to confining the underlying Upper Floridan aquifer (Matthews and Krause, 1984).…”