Physical and Hydrochemical Evidence of Lake Leakage near Jim Woodruff Lock and Dam and of Ground-Water Inflow to Lake Seminole, and an Assessment of Karst Features in and near the Lake, Southwestern Georgia and Northwestern Florida Prepared in cooperation with the Georgia Department of Natural Resources Environmental Protection Division Scientific Investigations Report 2005-5084 U.S. Department of the Interior U.S. Geological Survey Cover photographs, clockwise from top left: Boat-mounted acoustic Doppler current profiling apparatus in use near the River Boil; looking north from Apalachicola River toward Jim Woodruff Lock and Dam in background. Photograph by Lynn J. Torak, U.S. Geological Survey River Boil on Apalachicola River, about 900 feet downstream of Jim Woodruff Lock and Dam, near Chattahoochee, Florida. Photograph by Lynn J. Torak, U.S. Geological Survey Vortex flow entering sinkhole in the bottom on Lake Seminole at a depth from about 8 to 10 feet, located along the western shore of the lake about one-half mile from Jim Woodruff Lock and Dam near Sneads, Florida. Photograph by Harley Means, Florida Geological Survey Nonisokinetic thief sampler (Van Dorn sampler) in use at State Dock Spring on Flint River impoundment arm of Lake Seminole, Bainbridge, Georgia. Photograph by Lynn J. Torak, U.S. Geological Survey Physical and Hydrochemical Evidence of Lake Leakage near Jim Woodruff Lock and Dam and of Ground-Water Inflow to Lake Seminole, and an Assessment of Karst Features in and near the Lake, Southwestern Georgia and Northwestern Florida By Lynn J. Torak, Dianna M. Crilley, and Jaime A. Painter Prepared in cooperation with the Georgia Department of Natural Resources Environmental Protection Division Scientific Investigations Report 2005–5084 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior P. Lynn Scarlett, Acting Secretary U.S. Geological Survey P. Patrick Leahy, Acting Director U.S. Geological Survey, Reston, Virginia: 2006 This report is a Web-only publication: pubs.usgs.gov/sir/2005/5084/ For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/ Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted materials contained within this report. Suggested citation: Torak, L.J., Crilley, D.M., and Painter, J.A., 2006, Physical and hydrochemical evidence of lake leakage near Jim Woodruff Lock and Dam and of ground-water inflow to Lake Seminole, and an assessment of karst features in and near the lake, southwestern Georgia and northwestern Florida: U.S. Geological Survey Scientific Investigations Report 2005-5084, 90 p. iii Contents Abstract ........................................................................................................................................................... 1 Introduction..................................................................................................................................................... 2 Purpose and Scope .............................................................................................................................. 3 Previous Studies ................................................................................................................................... 4 Acknowledgments ................................................................................................................................ 4 Study Area.............................................................................................................................................. 5 Climate ........................................................................................................................................... 5 Physiography and Drainage ....................................................................................................... 7 Geologic Framework ..................................................................................................................................... 7 Hydrogeologic Framework ........................................................................................................................... 11 Hydrochemistry .............................................................................................................................................. 13 Physical Evidence of Lake Leakage near Jim Woodruff Lock and Dam and of Ground- Water Inflow to the Lake ................................................................................................................. 15 Comparison of Ground-Water Levels with Lake and Stream Stage ............................................ 15 Results of Dye-Tracing Experiments and Acoustic Doppler Current Profiling ........................... 22 Streamflow Gain along Spring Creek ................................................................................................ 24 Water-Temperature Variation at In-Lake and Off-Channel Springs ............................................. 25 Geologists’ Accounts of Limestone-Dissolution Features Found during Site Exploration and Dam Construction ....................................................................................... 28 Hydrochemical Evidence of Lake Leakage and Ground-Water Inflow to Lake Seminole ................. 34 Water-Chemistry Sampling ................................................................................................................. 34 Physical and Chemical Properties ..................................................................................................... 35 Ground-Water Chemistry ..................................................................................................................... 35 Surface-Water Chemistry .................................................................................................................... 38 Springflow Chemistry ........................................................................................................................... 40 Solute-Tracer Analysis ......................................................................................................................... 40 Radon-222...................................................................................................................................... 41 Deuterium and Oxygen-18 Stable Isotopes ............................................................................ 41 Isotope Mixing-Model Results ........................................................................................................... 43 Assessment of Limestone Dissolution and Potential for Lake Leakage into Karst Features Underlying Lake Seminole ............................................................................................................. 45 Calcite-Saturation Indices .................................................................................................................. 45 Remote-Sensing Techniques and Interactive Map ......................................................................... 47 Instructions to Download, Install, and Use Interactive Map ................................................ 47 Comparison of Preimpoundment Aerial Photographs with Mapped Navigational Features .................................................................................................. 48 Comparison of Preimpoundment Aerial Photographs with Hydrographic Surveys ......... 52 Physical and Hydrochemical Factors Affecting Leakage Potential and Sinkhole Collapse .................................................................................................................... 55 Monitoring Changes in Physical and Hydrochemical Components of the Flow System to Evaluate Lake Leakage .................................................................................................................... 55 Conclusions..................................................................................................................................................... 56 Literature Cited ............................................................................................................................................... 58 Appendix.......................................................................................................................................................... 63 iv Figures 1–2. Maps Showing— �� Location of study area, Lake Seminole, boundaries of the lower Apalachicola– Chattahoochee–Flint River Basin, and physiographic districts of the Coastal Plain province .......................................................................................................... 2 2. Physiographic divisions and drainage features of the Lake Seminole study area .... 5 3. Graph showing precipitation and air temperature for Colquitt, Georgia .............................. 6 4. Chart showing geologic and hydrologic units in the Lake Seminole study area and general description of ground-water chemistry of water-bearing units .............................. 8 5. Hydrostratigraphic sections A–A’ and B–B ’ and locations of wells used to construct sections through the Lake Seminole study area ..................................................... 12 6. Conceptual diagram of ground-water and surface-water flow in the interconnected