Water-Resources Investigations Report 99-4140

HYDROGEOLOGY AND WATER QUALITY OF THE UPPER FLORIDAN AQUIFER, WESTERN ALBANY AREA, GEORGIA

This report is available online in pdf format (3 MB): USGS WRIR99-4140 (Opens the PDF file in a new window. )

Lisa M. Stewart, Debbie Warner, and Barbara J. Dawson

U.S. Geological Survey Water-Resources Investigations Report 99-4140, 42 pages (Published 1999)

ABSTRACT

Geologic, hydrologic, and water-quality data were collected to refine the hydrogeologic framework conceptual model of the Upper Floridan aquifer, and to qualitatively evaluate the potential of human activities to impact water quality in the Upper Floridan aquifer in the western Albany area, Georgia. Groundwater age dating was conducted by using chlorofluorocarbons (CFC) and tritium concentrations in water from the Upper Floridan aquifer to determine if recharge and possible contaminant migration to the aquifer is recent or occurred prior to the introduction of CFCs and tritium in the early 1950’s into the global natural water system. Data were collected from core holes and wells installed during this study and previously existing wells in the Albany area.

Hydrogeologic data collected during this study compare well to the regional hydrogeologic conceptual model developed during previous studies. However, the greater data density available from this study shows the dynamic and local variability in the hydrologic character of the Upper Floridan aquifer in more detail. The occurrence of sediment sizes from clay to gravel in the overburden, the absence of overburden because of erosion or sinkhole collapse, and large areas lacking surface drainage west of the Flint River provide potential areas for recharge and contaminant migration from the surface to the Upper Floridan aquifer throughout the study area. Ground-water ages generally range from 9 to 34 years, indicating that recharge consisting of “modern” water (post early- 1950’s) is present in the aquifer. Ground-water ages and hydraulic heads in the Upper Floridan aquifer have an irregular distribution, indicating that localized areas of recharge to the aquifer are present in the study area.

Generally, water in the Upper Floridan aquifer is calcium-bicarbonate rich, having low concentrations of magnesium, potassium, sodium, chloride, and sulfate. Water in the Upper Floridan aquifer is oxygenated, having dissolved-oxygen concentrations greater than 2 milligrams per liter. Nitrite-plus-nitrate as nitrogen, is present in the aquifer at concentrations ranging from less than 0.02 to 5.5 milligrams per liter. Areas of higher nitrate concentrations in the aquifer, coupled with widely distributed localized recharge to the aquifer indicates that suburban residential and agricultural land use in the western Albany area may affect water quality in the Upper Floridan aquifer. However, concentrations exceeding drinking water criteria were not detected in the study area.


CONTENTS

Abstract

Introduction

Purpose and Scope

Description of study area

Previous investigations and regional conceptual model of the Upper Floridan aquifer

Geologic units

Hydrology

Acknowledgments

Methods of investigation

Well, spring, and water-filled cave inventory

Observation wells

Well construction and well distribution in the Upper Floridan aquifer

Lithologic and geophysical data

Ground-water levels

Ground-water sampling and quality assurance

Ground-water age dating by using chlorofluorocarbons and tritium

Hydrogeology

Geologic units

Lisbon Formation

Ocala Limestone

Undifferentiated overburden

Hydrology

Surficial aquifer

Upper Floridan aquifer

Ground-water levels

Potentiometric surface and directions of ground-water flow

Recharge and discharge

Chlorofluorocarbon and tritium calculated ground-water ages

Water quality in the Upper Floridan aquifer

Summary and conclusions

References cited

 


REPORT AVAILABILITY

This report is available online in pdf format (3 MB): USGS WRIR99-4140 (Opens the PDF file in a new window. )
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