PILOT STUDY OF GROUNDWATER CONDITIONS IN THE JOY ROAD, MARK WEST SPRINGS, AND BENNETT VALLEY AREAS OF SONOMA COUNTY, CALIFORNIA September 17, 2003 Copyright 2003, Kleinfelder, Inc. All Rights Reserved UNAUTHORIZED USE OR COPYING OF THIS DOCUMENT IS STRICTLY PROHIBITED. SEE “APPLICATION FOR AUTHORIZATION TO USE” LOCATED AT THE END OF THIS DOCUMENT IF USE OR COPYING IS DESIRED BY ANYONE OTHER THAN THE CLIENT FOR THE SPECIFIC PROJECT. 41-478401\SRO3R057 September 17, 2003 © 2003 Kleinfelder, Inc. TABLE OF CONTENTS Section Page 1. INTRODUCTION ...............................................................................................................1 1.1 Background......................................................................................................................1 1.2 Project Overview .............................................................................................................1 2. JOY ROAD STUDY AREA................................................................................................5 2.1 Study Area Boundaries ....................................................................................................5 2.2 Topography......................................................................................................................5 2.3 Drainage...........................................................................................................................5 2.4 Geology............................................................................................................................6 2.4.1 Franciscan Formation...................................................................................................6 2.4.2 Merced Formation........................................................................................................6 2.4.3 Alluvium ......................................................................................................................7 2.5 Precipitation .....................................................................................................................7 2.6 Run-Off............................................................................................................................8 2.7 Evapotransporation ..........................................................................................................8 2.8 Land Use ..........................................................................................................................8 2.9 Residential Land Use .......................................................................................................8 2.10 Historic Residential Use ..................................................................................................9 2.11 Current Residential Water Demand .................................................................................9 2.12 Historical Residential Water Demand ...........................................................................10 2.13 Future Residential Use Trends.......................................................................................10 2.14 Agricultural Use.............................................................................................................10 2.15 Historic Agricultural Use...............................................................................................11 2.16 Current Agricultural Water Demand .............................................................................11 2.17 Historical Agricultural Water Demand..........................................................................12 2.18 Future Agricultural Trends ............................................................................................12 2.19 Comparative Water Use.................................................................................................13 2.20 Constraints On Groundwater Availability .....................................................................13 3. MARK WEST STUDY AREA .........................................................................................15 3.1 Topography....................................................................................................................15 3.2 Drainage.........................................................................................................................15 3.3 Geology..........................................................................................................................16 3.3.1 Sonoma Volcanics .....................................................................................................16 3.3.2 Glen Ellen ..................................................................................................................16 3.4 Precipitation ...................................................................................................................17 3.5 Run-Off..........................................................................................................................17 3.6 Evapotransporation ........................................................................................................17 3.7 Residential Land Use .....................................................................................................18 3.8 Historic Residential Use ................................................................................................18 3.9 Current Residential Water Demand ...............................................................................18 3.10 Historical Residential Water Demand ...........................................................................19 3.11 Future Residential Use Trends.......................................................................................19 41-478401\SRO3R057 Page iii of v September 17, 2003 © 2003 Kleinfelder, Inc. 3.12 Agricultural Use.............................................................................................................19 3.13 Historic Agricultural Use...............................................................................................19 3.14 Current Agricultural Water Demand .............................................................................20 3.15 Historical Agricultural Water Demand..........................................................................20 3.16 Future Agricultural Trends ............................................................................................20 3.17 Golf Courses ..................................................................................................................21 3.18 Comparative Water Use.................................................................................................21 3.19 Constraints On Groundwater Availability .....................................................................21 4. BENNETT VALLEY STUDY AREA ..............................................................................23 4.1 Topography....................................................................................................................23 4.2 Drainage.........................................................................................................................23 4.3 Geology..........................................................................................................................23 4.3.1 Sonoma Volcanics .....................................................................................................24 4.3.2 Petaluma Formation...................................................................................................24 4.4 Precipitation ...................................................................................................................24 4.5 Run-Off..........................................................................................................................25 4.6 Evapotransporation ........................................................................................................25 4.7 Residential Land Use .....................................................................................................25 4.8 Historic Residential Use ................................................................................................26 4.9 Current Residential Water Demand ...............................................................................26 4.10 Historical Residential Water Demand ...........................................................................26 4.11 Future Residential Use Trends.......................................................................................27 4.12 Agricultural Use.............................................................................................................27 4.13 Historic Agricultural Use...............................................................................................27 4.14 Current Agricultural Water Demand .............................................................................27 4.15 Historic Agricultural Water Demand.............................................................................28 4.16 Future Agricultural Trends ............................................................................................28 4.17 Comparative Water Use.................................................................................................29 4.18 Geologic Constraints......................................................................................................29 5. STATISTICAL EVALUATION OF WELL LOG DATA................................................31