LLNL-TR-400426 Groundwater Availability Within the Salton Sea Basin Final Report Andrew Tompson Zafer Demir Jean Moran Denise Mason Jeff Wagoner Stefan Kollet Kayyum Mansoor and Peter McKereghan Lawrence Livermore National Laboratory January 29, 2008 LLNL-TR-400426 Groundwater Availability Within the Salton Sea Basin Final Report LLNL-TR-400426 Authors: Andrew Tompson Zafer Demir Jean Moran Denise Mason Jeff Wagoner Stefan Kollet Kayyum Mansoor Peter McKereghan January 29, 2008 Lawrence Livermore National Laboratory Livermore, California 94551 LLNL-TR-400426 Disclaimer This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes. Auspices Statement This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-TR-400426 Table of Contents Executive Summary...................................................................................1 Background.............................................................................................................. 1 Groundwater Availability in the Basin ................................................................... 2 Project Objectives.................................................................................................... 3 Findings and Conclusions ...................................................................................... 4 Additional Reccomendations.................................................................................. 5 Section 1: Introduction.............................................................................6 1.1 Background........................................................................................................ 6 1.2 Project Objectives............................................................................................ 10 1.3 Report Organization ........................................................................................ 11 Section 2: Physical Setting and Groundwater Occurrence .................12 2.1 Physical and Geologic Setting........................................................................ 12 2.1.1 Surface Water Hydrology........................................................................... 12 2.1.2 Groundwater Hydrology............................................................................. 14 2.1.3 Tectonic and Geothermal Activity .............................................................. 15 2.2 Paleohydrology ................................................................................................ 15 2.3 Groundwater Occurrence Today .................................................................... 16 2.3.1 Shallow Groundwater System ................................................................... 17 2.3.2 Groundwater Recharge ............................................................................. 17 2.3.3 Canal and River Leakage .......................................................................... 24 2.3.4 Natural Groundwater Discharges .............................................................. 26 2.3.5 Deeper Groundwater System .................................................................... 26 2.4 Groundwater Production................................................................................. 28 2.4.1 Background ............................................................................................... 28 2.4.2 New Groundwater Production from the Shallow System ........................... 28 2.4.3 New Groundwater Production from the Deeper System............................ 30 2.4.4 Wells, production data, and related aquifer characterization information .. 30 Section 3: Phase I Database and GIS Model Development..................33 3.1 Project Database.............................................................................................. 33 iii Ground Water Availability within the Salton Sea Basin: A Final Report Lawrence Livermore National Laboratory LLNL-TR-400426 3.1.1 Literature Reference Database and Library............................................... 33 3.1.2 Salton Sea Water Resources Database .................................................... 35 3.2 Project Website Development......................................................................... 40 Section 4: Phase I Database and GIS Products ....................................42 Section 5: Concepts for Phase II Activities ...........................................55 5.1 Purpose and Scope ......................................................................................... 55 5.2 Overview of Potential Phase II Topics ........................................................... 55 5.2.1 Continued Database Development............................................................ 55 5.2.2 Refinement of Basin Conceptual Model .................................................... 56 5.2.3 Field Data Acquisition Program ................................................................. 58 5.2.4 Modeling Assessment of Groundwater Availability .................................... 58 5.3 Identified Phase II Tasks ................................................................................. 59 5.3.1 Groundwater Age and Recharge Source Assessment in the East Mesa... 59 5.3.2 Groundwater Model Development in the Imperial Valley Area .................. 60 Section 6: Phase II Groundwater Sampling and Isotopic Analyses in the East Mesa Area ..................................................................................61 6.1 Overview........................................................................................................... 61 6.2 Isotopic Tracers in Groundwater.................................................................... 62 6.2.1 Tritium-Helium Age Dating Techniques ..................................................... 62 6.2.2 Stable Isotopes as Tracers of Recharge Source and Evaporation ............ 63 6.2.3 Other Tracers used for Groundwater Dating and Source Identification ..... 69 6.3 Sampling Trips................................................................................................. 69 6.3 Sampling Results and Interpretation ............................................................. 74 6.4 Future Sampling Opportunities ...................................................................... 78 Section 7: Phase II Groundwater Model Development in the Imperial Valley.........................................................................................................80 7.1 Groundwater Model Specification .................................................................. 82 7.1.1 Model Domain ........................................................................................... 82 7.1.2 Model Grid................................................................................................. 82 7.1.3 Model Structure ......................................................................................... 83 7.1.4 Regional Groundwater Elevation Map ....................................................... 86 iv Ground Water Availability within the Salton Sea Basin: A Final Report Lawrence Livermore National Laboratory LLNL-TR-400426 7.1.5 Boundary Conditions: First Pass ............................................................... 86 7.1.6 Recharge Estimates .................................................................................. 89 7.1.7 Groundwater Withdrawals ......................................................................... 91 7.1.8 Hydraulic Conductivity and Porosity in the Shallow System ...................... 91 7.1.9 Hydraulic Conductivity and Porosity in the Deeper System....................... 92 7.2 A Preliminary Model Result and Discussion ................................................. 96 7.3 Working Towards a Calibrated and Tested Model ........................................ 99 Section 8: Summary, Conclusions and Recommendations...............101 8.1 Summary ........................................................................................................ 101 8.2 Findings and Conclusions ............................................................................ 103 8.3 Additional Recommendations ...................................................................... 104 8.3.1 Continued Groundwater Model Development.......................................... 104 8.3.2 Additional Isotopic Sampling in the East Mesa........................................ 104 8.3.3 Precipitation, Runoff, and Evapotranspiration Along the Western Basin . 104 8.3.4