TEXAS WATER COMMISSION REPORT 88-01 GROUND-WATER RESOURCES OF THE ANDERSON COUNTY UNDERGROUND WATER CONSERVATION DISTRICT (ANDERSON COUNTY, TEXAS) By Jimmie N. Russell Joseph L. Peters February 1988 TEXAS WATER COMMISSION Paul Hopkins, Chairman John O. Houchins, Commissioner B. J. Wynne, III, Commissioner Allen Beinke, Executive Director Authorization for use or reproduction of any originalmaterialcontainedin this publication, i.e., not obtained from other sources, is freely granted. The Commission would appreciate acknowledgement. Published and distributed by the Texas Water Commission Post Office Box 13087 Austin, Texas 78711 TABLE OF CONTENTS Page INTRODUCTION 1 Purpose and Scope 1 Location 1 Method of Investigation 1 Personnel 7 Well Numbering System 7 Acknowledgements 7 GEOLOGY OF THE KEECHI SALT DOME 7 CARRIZO-WILCOX AQUIFER 15 Recharge, Discharge, Movement 15 Hydraulic Characteristics 15 Chemical Quality 23 Aquifer Development and Decline of Water Levels 23 Availability of Ground Water for Future Development 24 CONCLUSIONS AND RECOMMENDATIONS 25 REFERENCES 33 TABLES 1. Records of Selected Wells in Anderson County 34 2. Selected Wells Used for Control and Basic Data 41 FIGURES 1. Location of the Anderson County Underground Water Conservation District and Study Area 2 2. Location of Selected Wells Used for Control and Basic Data 3 TABLE OF CONJENTS-Continued Page 3. Location of Inventoried Water Wells in the Anderson County Underground Water Conservation District 5 4. Well Numbering System 9 5. Geologic Map 11 6. Altitude of Water Levels in the Carrizo-Wilcox Aquifer 13 7. Approximate Thickness of the Carrizo Sand Containing Ground Water 17 8. Approximate Thickness of the Wilcox Group Containing Ground Water 19 9. Depth to and Altitude of the Top of the Carrizo Sand 21 10. Time Versus Drawdown (Time = 1 Year) 25 11. Time Versus Drawdown (Time = 20 Years) 26 12. Predicted Decline of Water Levels in a Proposed Well Field Under Artesian Conditions Northeast of the KeechiSalt Dome 29 13. Predicted Decline of Water Levels in a Proposed Well Field Under Water-Table Conditions Over the Keechi Salt Dome 31 IV GROUND-WATER RESOURCES OF THE ANDERSON COUNTY UNDERGROUND WATER CONSERVATION DISTRICT (ANDERSON COUNTY, TEXAS) INTRODUCTION Method of Investigation As stated above, one of the primary objectives Purpose and Scope of this study was to simulate the Carrizo-Wilcox aquifer with a computer model. The simulation process allows the prediction of water-level de The purpose of this report is to present the clines based on projected pumpage, and the pre results of a study that was made to: 1) determine dicted water-level declines provide a means for the hydrogeologic characteristics of the Carrizo- evaluating the ability of the aquifer to meet antici Wilcox aquifer in the vicinity of the Keechi Salt pated ground water withdrawal requirements. To Dome, Anderson County; 2) inventory all water obtain the necessary inputs for the modeling effort, wells within the Anderson County Underground data and published reports pertinent to the study Water Conservation District; and 3) to use a com area were retrieved to establishthe hydrogeological puter model of the Carrizo-Wilcox aquifer to evalu framework. ate the response to pumping in the vicinity of the Keechi Dome, and the probable future ground Although wells were not sampled in this study, water conditions. The study consisted of in-office analyses of water from wells in and near this area compilations and analyses of available data, com that are shown in Report 150 of the Texas Water puter simulations, field work, and the writing of a Development Board were reviewed. These data technical report. regarding water quality are assumed representa tive of the conditions in the report area and are briefly summarized in this report in terms of total concentration of soluble salts. Location Electrical logs of wells in and near the report The study area of this report is approximately area (Figure 2 and Table 2), most of which were centered on the Keechi salt dome. The Keechi drilled foroil and gas, were analyzed to provide the dome is in central Anderson County, about seven data that wereusedto constructthe mapsthat show miles northwest of Palestine, and is on State High the geological structure, net sand, and total thick way 19. The nearest town is Montalba, which is ness of the Carrizo Sand and the Wilcox Group. about three miles to the northwest, and the nearest These maps are included in this report. riveristhe Trinity,which is about eleven miles to the west of the dome. The dome is at 31°50'19" north An inventorywas made inthe field to locate and latitude and 95°42'20" west longitude. The study obtain data on all wells in the District (Figure 3) area, location of the Keechi Salt Dome, and which have been drilled for municipal, industrial, boundaries of the Anderson County Underground and irrigation purposes, and wells used for domes Water Conservation District are shown on Figure 1. tic and livestock supplies. Information on the vari- Figure 1 Location of the Anderson County Underground Water Conservation District and Study Area ous wells was obtained from well owners and second quadrangle 9, in 16 2/3-second quadrangle through field investigative methods. A number was 3, in 5 1/2-second quadrangle 7, and in 1 5/6- assigned for each well according to the system second quadrangle 6. (See Figure 4.) described below (Figure 4), and a determination was made of the formation supplying its water, as indicated by available well records, the geologic Acknowledgements map (Figure 5: Barnes, 1968, and Ebanks, 1965), and nearby well logs. Depth to water measure The contributions and cooperation of the many ments were made in wells where this was practi Anderson County residents who assisted with the cable. inventory of water wells are especially appreciated. Data and helpful comments were obtained from the Texas Water Development Board, particularly from Personnel David Thorkildsen. The constructive review of this report by Robert Price of the TWC contributed This study was conducted by Texas Water materially to the success of this project. The Commission staff. In-office compilations and re gracious permission granted by Mr.G. K. Ebanks to views were made by J. N. Russell, Brad Cross and use the information from his University of Texas David Prescott, and the latter two additionally con Master of Arts thesis on the geology of the Keechi ducted a field inventory of water wells within the dome materially aided in the preparation of this proposed water district. Computer simulations report. were set up and run by Joseph L. Peters. GEOLOGY OF THE KEECHI Well Numbering System SALT DOME As indicated in Figure 4, the well numbering Keechi is a piercement salt dome that is highly system for this report is based on longitude and elliptical with the 4.6 mile-long major axis oriented N latitude, with each well being assigned a nine-digit 15°E, and the minor axis is 1.7 miles long. An number. anhydrite cap rock is present over most, but not all of the dome, and the cap has a maximum thickness Each 1-degree quadrangle in or overlapping of 300 feet. The minimum depth to cap rock and salt into the State is given a two-digit number from 01 to is 250 and 300 feet, respectively. The salt has not 89. These are the first two digits of a well number. been mined, nor has it been used for petroleum Each 1-degree quadrangle is further divided into storage. There has not been any production of sixty-four 71 /2-minute quadrangles which are each sulfur or hydrocarbons at the Keechi dome. assigned a two-digit number from 01 to 64. These two digits constitute the third and fourth digits of a The upward movement of the salt mass af well number. Each 7 1/2-minute quadrangle is fected the overlying stratigraphic units. Erosion of subdivided into nine 2 1/2-minute quadrangles uplifted units has resulted in exposure at the land which are numbered 1 to 9. This is the fifth digit of surface over the crest of the dome of older-aged a well number. This process of subdividing each geologic formations that are approximately ringed progressively smallerquadrangle by nine is carried by a succession of progressively younger forma out four more times for a nine-digit well number. tions. The geologic map of the study area (Figure The ultimate quadranglesize is lessthan 2-seconds 5) illustrates the geological features, as well as, the square, covering an area of approximately 175 effects of the upward movement of the Keechi square feet. Dome. This area of Anderson County is covered by 1- Faults are present in the crestal area of the degree quadrangle number 38. The 7 1/2-minute dome. The faults mostly trend northeast-south quadrangles are numbers 03, 10, 11 and 12. west. Intersecting cross faults possibly limit ground-water recharge to separated fault blocks; Thus, Well Number 38-11-99376 would be this may be reflected in the water levels shown on located in 1-degree quadrangle 38, in 7 1/2-minute Figure 6. quadrangle 11, in 2 1/2-minute quadrangle 9, in 50- THE CARRIZO-WILCOX AQUIFER Eventually the water is discharged from the aquifer. This can occur at the land surface at seeps The Carrizo-Wilcox aquifer, which is the major or by evapotranspiration. However, it can also be aquifer in this area, is defined for the purposes of discharged at wells, either by flowing or pumping. this report to include the Carrizo Sand and the Large scale production from wells can alter the underlying Wilcox Group. The Carrizo-Wilcox is piezometric surface and flow pattern.