Final Report Updating the Hydrogeologic Framework for the Northern Portion of the Gulf Coast Aquifer Prepared by Steven C. Young, Ph.D., P.E., P.G. Tom Ewing, Ph.D., P.G Scott Hamlin, Ph.D., P.G. Ernie Baker, P.G. Daniel Lupton Prepared for: Texas Water Development Board P.O. Box 13231, Capitol Station Austin, Texas 78711-3231 June 2012 Texas Water Development Board Final Report Updating the Hydrogeologic Framework for the Northern Portion of the Gulf Coast Aquifer Steven C. Young, Ph.D., P.E., P.G. Daniel Lupton INTERA Incorporated Tom Ewing, Ph.D., P.G. Frontera Exploration Consultants Scot Hamlin, Ph.D., P.G Ernie Baker, P.G. June 2012 This page is intentionally blank. ii Final Report – Updating the Hydrogeologic Framework for the Northern Portion of the Gulf Coast Aquifer Table of Contents Executive Summary ..................................................................................................................... xiii 1.0 Introduction ........................................................................................................................ 1-1 1.1 Approach for Defining Stratigraphy ......................................................................... 1-2 1.2 Approach for Defining Lithology and Generating Sand Maps ................................ 1-3 2.0 Gulf Coast Aquifer Geologic Setting ................................................................................. 2-1 2.1 Overview ................................................................................................................... 2-1 2.2 Structural Features .................................................................................................... 2-4 2.2.1 Faulting and Subsidence ............................................................................... 2-4 2.2.2 Salt Domes in Southeast Texas and Southwest Louisiana ........................... 2-7 2.2.2.1 Salt Dome Geology ...................................................................... 2-8 2.2.2.2 Natural Resources ...................................................................... 2-12 2.2.2.3 Groundwater Chemistry ............................................................. 2-16 2.3 Depositional Systems.............................................................................................. 2-17 2.4 Depositional History ............................................................................................... 2-18 3.0 Stratigraphic and Hydrogeologic Framework .................................................................... 3-1 3.1 Previous Studies........................................................................................................ 3-1 3.2 Fleming Group: Oakville and Lagarto Formations ................................................. 3-4 3.3 Goliad Formation ...................................................................................................... 3-8 3.4 Willis Formation ..................................................................................................... 3-12 3.5 Lissie Formation ..................................................................................................... 3-13 3.6 Beaumont Formation .............................................................................................. 3-13 3.7 Holocene Deposits .................................................................................................. 3-14 4.0 Information sources ............................................................................................................ 4-1 4.1 Geophysical Logs ..................................................................................................... 4-1 4.1.1 Resistivity Logs ............................................................................................ 4-2 4.1.2 Spontaneous Potential Logs ......................................................................... 4-3 4.1.3 American Petroleum Institute Format .......................................................... 4-4 4.2 Approach for Obtaining Geophysical Logs .............................................................. 4-5 4.2.1 Geophysical logs' Sources ............................................................................ 4-6 4.2.2 Geophysical Logs Selected for the Study ..................................................... 4-6 4.3 Literature Review ..................................................................................................... 4-7 4.4 Paleontology Data ..................................................................................................... 4-8 5.0 Approach for Stratigraphic Interpretation .......................................................................... 5-1 5.1 Chronostratigraphic Conceptual Framework ............................................................ 5-1 5.2 Methodology ............................................................................................................. 5-4 6.0 Gulf Coast Aquifer Stratigraphy ........................................................................................ 6-1 6.1 Chronostratigraphic Surfaces and Aquifer Boundaries ............................................ 6-1 6.2 Structural Configuration of Surfaces ........................................................................ 6-2 iii Final Report – Updating the Hydrogeologic Framework for the Northern Portion of the Gulf Coast Aquifer 7.0 Approach for Lithologic Interpretation .............................................................................. 7-1 7.1 Lithology Classification ............................................................................................ 7-1 7.2 Depositional Facies Classification ............................................................................ 7-2 8.0 Gulf Coast Aquifer Lithology ............................................................................................ 8-1 8.1 Sand Thickness and Percent ..................................................................................... 8-1 8.1.1 Chicot Aquifer .............................................................................................. 8-3 8.1.2 Evangeline Aquifer ....................................................................................... 8-3 8.1.3 Middle Lagarto (Burkeville confining unit) ................................................. 8-3 8.1.4 Jasper Aquifer ............................................................................................... 8-4 8.2 Depositional Facies ................................................................................................... 8-4 8.2.1 Chicot Aquifer .............................................................................................. 8-5 8.2.2 Evangeline Aquifer ....................................................................................... 8-5 8.2.3 Middle Lagarto Unit (Burkeville confining unit) ........................................ 8-6 8.2.4 Jasper Aquifer ............................................................................................... 8-6 9.0 Gulf Coast Water Quality ................................................................................................... 9-1 9.1 Terminology ............................................................................................................. 9-1 9.1.1 Fresh and Brackish Groundwater ................................................................. 9-1 9.1.2 Total Dissolved Solids and Specific Conductivity ....................................... 9-1 9.2 Analysis of Geophysical Logs .................................................................................. 9-3 9.2.1 Approach ..................................................................................................... 9-3 9.2.2 Results .......................................................................................................... 9-4 9.3 Analysis of Water Well Measurements .................................................................... 9-7 9.3.1 Approach ...................................................................................................... 9-7 9.3.2 Results .......................................................................................................... 9-7 10.0 References ........................................................................................................................ 10-1 Appendix A Geophysical Logs Listing, including Location and Use Appendix B Listing of Geophysical Logs Stratigraphic Contacts Appendix C Estimated Total Sand Thickness at Each Geophysical Log Location Appendix D Response TWDB Comments on Draft Report and Responses to Comments iv Final Report – Updating the Hydrogeologic Framework for the Northern Portion of the Gulf Coast Aquifer List of Figures Figure 1-1 Map of the study area showing the locations of the dip-oriented and strike- oriented cross-sections used to develop the stratigraphic surfaces. ..................... 1-5 Figure 2-1 Map of the Gulf of Mexico basin showing major structural elements and stratigraphic provinces. Modified from Ewing (1991). .................................... 2-21 Figure 2-2 Regional dip-oriented cross section of Cenozoic strata on the northwestern margin of the Gulf of Mexico basin. Modified from Galloway and others (1991) and Sharp and others (1991)................................................................... 2-21 Figure 2-3 Map showing major growth fault zones and shallow salt domes in the onshore part of the Texas coastal zone. Modified from Ewing