U.S. Department of the Interior U.S. Geological Survey � H A N S O N A � N D O T H E R S – A G T E O M H A Y R D I R N O A L , O M G O Y N O T F E A R E D Y E C E O P - U A N Q T U Y I , F C E R A Deep-Aquifer L M I O O Monitoring-Well F N O I R T Site N O I R A I N G Marina Coast - W Water District E L L S I T E GEOHYDROLOGY OF A DEEP-AQUIFER MONITORING-WELL SITE AT MARINA, W R I R 0 2 - 4 MONTEREY COUNTY, CALIFORNIA 0 0 3 Prepared in cooperation with MONTEREY COUNTY WATER RESOURCES AGENCY Water-Resources Investigations Report 02-4003 Base image for cover illustration provided courtesy of the Monterey Bay Aquarium Research Institute. Geohydrology of a Deep-Aquifer System Monitoring-Well Site at Marina, Monterey County, California By R.T. Hanson, Rhett R. Everett, Mark W. Newhouse, Steven M. Crawford, M. Isabel Pimentel, and Gregory A. Smith U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 02–4003 Prepared in cooperation with the Monterey County Water Resources Agency 4024-13 Sacramento, California 2002 U.S. DEPARTMENT OF THE INTERIOR GALE A. NORTON, Secretary U.S. GEOLOGICAL SURVEY Charles G. Groat, Director The use of firm, trade, and brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. For additional information write to: Copies of this report can be purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Information Services Placer Hall, Suite 2012 Box 25286 6000 J Street Federal Center Sacramento, CA 95819-6129 Denver, CO 80225 CONTENTS Abstract.................................................................................................................................................................................. 1 Introduction ........................................................................................................................................................................... 2 Description of Study Area ........................................................................................................................................... 3 Land and Water Use..................................................................................................................................................... 3 Geohydrology of The Salinas Valley ........................................................................................................................... 3 Approach to Investigation............................................................................................................................................ 6 Acknowledgments ....................................................................................................................................................... 6 Geohydrologic Description of DMW1 .................................................................................................................................. 8 Geologic Data .............................................................................................................................................................. 8 Geophysical Data......................................................................................................................................................... 12 Paleontologic Data....................................................................................................................................................... 18 Hydrostratigraphy of DMW1 Site ............................................................................................................................... 18 Hydraulics.............................................................................................................................................................................. 20 Water-Level Measurements ......................................................................................................................................... 21 Hydraulic Properties .................................................................................................................................................... 21 Water Chemistry .................................................................................................................................................................... 22 Chemical Characteristics of Water from Monitoring and Supply Wells ..................................................................... 22 Source, Age, and Movement of Ground Water............................................................................................................ 23 Seawater Intrusion and Saline Ground Water.............................................................................................................. 25 Summary and Conclusions .................................................................................................................................................... 33 References Cited.................................................................................................................................................................... 34 Appendix 1: Cuttings and Core Descriptions for the DMW1 Monitoring Site..................................................................... 38 Appendix 2: Paleontologic Analyses for the DMW1 Monitoring Site.................................................................................. 65 Appendix 3: Water-Chemistry Data for the DMW1 Monitoring Wells and Core Pore Waters............................................. 69 FIGURES 1. Map showing location of deep-aquifer system monitoring-well site in the Salinas Valley, at Marina, California 4 2. Map showing location of deep-aquifer system monitoring-well site and selected water-supply wells, Marina, California ............................................................................................................................................................... 5 3. Schematic diagram showing well construction and lithology for the deep-aquifer system, Marina, California... 7 4. Photographs of cores 1 to 19 from the deep-aquifer system monitoring-well site, Marina, California ................ 9 5–13. Graphs showing: 5. Lithology and geophysical logs for the deep-aquifer system monitoring-well site, Marina, California....... 13 6. Acoustic and borehole inclinometer geophysical logs for the deep-aquifer system monitoring-well site, Marina, California ......................................................................................................................................... 14 7. Multi-spectral natural gamma geophysical logs for the deep-aquifer system monitoring-well site, Marina, California ......................................................................................................................................... 15 8. Geophysical logs for the deep-aquifer system monitoring-well site, Marina, California ............................. 17 9. Relation between chloride concentration and electromagnetic conductivity for core pore-water and well-water samples from the deep-aquifer system monitoring-well site, Marina, California ...................... 19 10. Trilinear diagram of major-ion chemistry for selected ground-water samples from the deep-aquifer system in the Salinas Valley, 1995, 1997, and 2000 with samples from DMW-1 wells, 2000...................... 24 11. Ratios of chloride-to-boron, chloride-to-iodide, and chloride-to-bromide plotted against chloride for ground-water and surface-water samples in the Salinas Valley, California................................................... 26 12. Deuterium and oxygen isotope values for selected ground-water and surface-water samples from the Salinas Valley, California............................................................................................................................... 29 13. Strontium-87/86 ratios plotted against strontium, and boron-11 plotted against chloride-to-boron ratios for selected wells in the Salinas Valley, California.............................................................................. 30 Contents III TABLES 1. Summary of well completion for the deep-aquifer system monitoring-well site, Marina, California...................... 8 2. Summary of slug-test estimates of hydraulic properties for the deep-aquifer system site, monitoring-well, Marina, California..................................................................................................................................................... 22 CONVERSION FACTORS, VERTICAL DATUM, WATER-QUALITY INFORMATION, ABBREVIATIONS, AND WELL- NUMBERING SYSTEM Multiply By To obtain inch (in.) 25.4 millimeter foot (ft) 0.3048 meter mile (mi) 1.609 kilometer square mile (mi2) 2.590 square kilometer acre-foot (acre-ft) 0.001233 cubic hectometer cubic foot per second (ft3/s) 0.02832 cubic meter per second foot per day (ft/d) 370.37037 millidarcy foot per day per foot (ft/d/ft) 1 meter per day per meter foot squared per day (ft2/d) 0.0929 meter squared per day gallon per minute (gal/min) 0.06308 liter per second Temperature is given in degrees Celsius (oC), which can be converted to degrees Fahrenheit (oF) by the following equation: oF = 1.8(oC) + 32. Vertical Datum Sea Level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD of 1929)--a geodetic datum derived from general adjustments of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929. Water-Quality Information