A PPENDIX I H YDROLOGY AND W ATER Q UALITY ........................................................................................................................ ........................................................................................................................ WATER SUPPLY ASSESSMENT FOR THE NAPA PIPE PROJECT NAPA COUNTY, CALIFORNIA AUGUST 25, 2011 WATER SUPPLY ASSESSMENT FOR THE NAPA PIPE PROJECT NAPA COUNTY, CALIFORNIA REVISED AUGUST 25, 2011 PREPARED BY WITH TECHNICAL ASSISTANCE BY WATER SUPPLY ASSESSMENT FOR THE NAPA PIPE PROJECT TABLE OF CONTENTS SECTION 1 EXECUTIVE SUMMARY ................................................................................... 1 1.1 Purpose and Scope of the Water Supply Assessment............................................ 1 1.2 The Project............................................................................................................. 2 1.3 Water Purveyor...................................................................................................... 3 1.4 Water Demands...................................................................................................... 3 1.5 Water Supplies....................................................................................................... 4 1.5.1 Groundwater .............................................................................................. 5 1.5.2 Imported Surface Water Supplies ............................................................ 10 1.5.3 Recycled Water Supplies ......................................................................... 11 1.5.4 City of Napa Water Supplies ................................................................... 14 1.6 Comparison of Water Supplies and Demands ..................................................... 16 SECTION 2 BACKGROUND ................................................................................................. 18 2.1 Description of the Project .................................................................................... 18 2.2 Climate................................................................................................................. 21 2.3 Water Purveyor.................................................................................................... 23 2.4 Legal Requirements ............................................................................................. 26 SECTION 3 WATER DEMANDS........................................................................................... 30 3.1 Historical and Current Water Demands............................................................... 30 3.2 Demands in Normal, Single Dry and Multiple Dry Water Years........................ 31 3.3 Water Quality....................................................................................................... 31 3.4 Projected Water Demands.................................................................................... 31 3.5 Water Efficiency Strategies ................................................................................. 33 3.6 Phasing of Projected Water Demands.................................................................. 34 SECTION 4 LOCAL GROUNDWATER SUPPLIES............................................................. 36 4.1 Basin Description and Applicable Technical Studies.......................................... 36 4.1.1 California Department of Water Resources............................................. 36 4.1.2 United States Geological Survey ............................................................. 38 4.1.3 Napa County............................................................................................ 39 4.1.4 City of Napa............................................................................................. 40 4.1.5 Investigation for the Project..................................................................... 41 AUGUST 25, 2011 i WATER SUPPLY ASSESSMENT FOR THE NAPA PIPE PROJECT 4.2 Local Groundwater Conditions............................................................................ 42 4.2.1 Occurrence of Groundwater..................................................................... 42 4.2.2 Historical and Existing Wells .................................................................. 43 4.2.3 Historical Pumping and Water Levels ..................................................... 44 4.2.4 Recent Field Investigations...................................................................... 47 4.2.5 Groundwater Quality............................................................................... 49 4.3 Groundwater Rights............................................................................................. 50 4.3.1 Legal Classification of Groundwater....................................................... 50 4.3.2 Groundwater Rights................................................................................. 50 4.3.3 Overlying Groundwater Rights................................................................ 51 4.3.4 Appropriative Groundwater Rights.......................................................... 52 4.3.5 Basin Management................................................................................... 53 4.3.6 County Groundwater Policies and Ordinances........................................ 54 4.4 Hydraulic Separation of the Sonoma Volcanics Aquifer..................................... 56 4.5 Groundwater Supply Estimate ............................................................................. 58 4.6 Other Local Groundwater Users .......................................................................... 58 4.6.1 City of Napa............................................................................................. 59 4.6.2 City of American Canyon ........................................................................ 60 4.6.3 Vineyards ................................................................................................. 61 4.6.4 Syar Industries Quarry ............................................................................. 61 4.6.5 Kennedy Park Golf Course ...................................................................... 62 4.6.6 Summary of Groundwater Users ............................................................. 62 4.7 Groundwater Level Impact Analysis ................................................................... 62 4.8 Interaction with Milliken-Sarco-Tulucay Basin .................................................. 63 4.9 Groundwater Monitoring and Mitigation Plan .................................................... 65 4.10 Impact of Climate Change on Local Groundwater.............................................. 66 4.11 Reliability Assessment......................................................................................... 68 SECTION 5 IMPORTED SURFACE WATER....................................................................... 71 5.1 Imported Surface Water....................................................................................... 71 5.2 Laws Affecting Water Right Assignment and Change........................................ 71 5.3 The Mill Creek Water Source.............................................................................. 72 5.3.1 Background Information and Description of Water Source .................... 72 ii AUGUST 25, 2011 WATER SUPPLY ASSESSMENT FOR THE NAPA PIPE PROJECT 5.3.2 Option Agreement.................................................................................... 81 5.3.3 Mill Creek Water Resources.................................................................... 81 5.3.4 Mill Creek Biological Resources............................................................. 83 5.3.5 Yield of the NRP Water Right................................................................. 89 5.3.6 Approach to Making Water Available..................................................... 92 5.3.7 Other Sources of Water............................................................................ 94 5.4 Diversion of Water at SWP Facilities.................................................................. 96 5.4.1 Introduction to the Delta .......................................................................... 96 5.4.2 Delta Water Infrastructure and Barker Slough Diversions...................... 96 5.4.3 General Condition of the Delta and Various Threats............................. 100 5.4.4 Environmental Litigation....................................................................... 105 5.4.5 Delta Planning Processes ....................................................................... 105 5.4.6 Water Conveyance Losses ..................................................................... 110 5.5 Water Conveyance............................................................................................. 114 5.5.1 Infrastructure.......................................................................................... 114 5.5.2 Conveyance Through SWP Facilities .................................................... 123 5.5.3 Agreement with the Cities ..................................................................... 124 5.6 Impacts of Climate Change on Imported Surface Water................................... 125 SECTION 6 RECYCLED WATER ....................................................................................... 130 6.1 Napa Sanitation District..................................................................................... 130 6.1.1 Overview of