This Page Intentionally Blank 43402 Business Park Drive Temecula, California 92590 951-676-6740 FAX: 951-676-6792 Western Municipal Water District Integrated Regional Water Management Plan 2008 Update May 2008 Prepared for Western Municipal Water District 450 Alessandro Blvd Riverside, CA K/J Project No. 0787128 This Project has been funded by a California Department of Water Resources Proposition 50, Integrated Regional Water Management Program Planning Grant. Table of Contents List of Tables................................................................................................................................ vi List of Figures.............................................................................................................................. vii List of Appendices.......................................................................................................................viii List of Abbreviations..................................................................................................................... ix Executive Summary ......................................................................................................................1 Section 1: Introduction and Plan Objectives ............................................. 1-1 1.1 Introduction .........................................................................................1-1 1.1.1 The IRWMP Update.................................................................1-1 1.1.2 Plan Preparation ......................................................................1-2 1.1.3 Plan Objectives ........................................................................1-3 Section 2: Description of the Regional Agency - Western Municipal Water District ............................................................................ 2-1 2.1 Description of Stakeholders ................................................................2-2 2.1.1 Box Springs Mutual Water Company.......................................2-2 2.1.2 City of Corona ..........................................................................2-1 2.1.3 City of Norco ............................................................................2-1 2.1.4 City of Riverside.......................................................................2-2 2.1.5 Eagle Valley Mutual Water Company ......................................2-2 2.1.6 Elsinore Valley Municipal Water District...................................2-3 2.1.7 Elsinore Water District..............................................................2-4 2.1.8 Home Gardens County Water District......................................2-4 2.1.9 Lee Lake Water District............................................................2-4 2.1.10 Rancho California Water District..............................................2-5 2.1.11 Western - Murrieta Division (Formerly Murrieta County Water District)..........................................................................2-6 2.1.12 Jurupa Community Services District ........................................2-7 2.1.13 Santa Ana River Water Company............................................2-7 2.1.14 Riverside Highlands Water Company ......................................2-8 2.1.15 Rubidoux Community Services District....................................2-8 2.2 Region Description: Santa Ana River Watershed ...............................2-9 2.2.1 Watershed Management Framework.......................................2-9 2.2.2 Watershed Areas and Management Plan ................................2-9 2.2.3 Surface Geology and Hydrology ..............................................2-9 2.2.4 Local Surface Water...............................................................2-10 2.2.4.1 Sources................................................................2-10 2.2.4.2 Water-Quality Summary.......................................2-11 2.2.5 Santa Ana River Watershed Groundwater Basins.................2-11 Western MWD – IRWMP - May 2008 TOC-i Table of Contents (cont'd) 2.2.5.1 Summary of Basin and Management Zone Boundaries...........................................................2-15 2.2.5.2 Summary of Subsurface Geology by Management Zones.............................................2-19 2.2.5.3 Groundwater Quality............................................2-26 2.2.5.4 Adjudication Judgments.......................................2-26 2.2.6 State Board Orders and Pending Water Rights Applications ...........................................................................2-30 2.3 Region Description: Santa Margarita River Watershed.....................2-31 2.3.1 Watershed Management Framework.....................................2-31 2.3.2 Watershed Areas and Management Plan ..............................2-31 2.3.3 Surface Geology and Hydrology ............................................2-32 2.3.4 Local Surface Water...............................................................2-32 2.3.4.1 Sources................................................................2-33 2.3.4.2 Water Quality .......................................................2-34 2.3.4.3 Adjudication Judgments.......................................2-34 2.3.5 Santa Margarita River Watershed Groundwater Basins ........2-34 2.3.5.1 Summary of Basin Boundaries ............................2-35 2.3.5.2 Summary of Subsurface Geology........................2-39 2.3.5.3 Groundwater Production......................................2-39 2.3.5.4 Groundwater Quality............................................2-45 Section 3: Relation to Other Planning Efforts............................................ 3-1 3.1 Southern California Association of Governments................................3-1 3.1.1 2008 Regional Comprehensive Plan........................................3-1 3.1.1.1 Applicability to Western..........................................3-2 3.2 Metropolitan Water District of Southern California ..............................3-3 3.2.1 Integrated Water Resources Plan............................................3-3 3.2.1.1 IWRP Goals ...........................................................3-3 3.2.1.2 Summary of Conclusions.......................................3-3 3.2.1.3 Applicability to Western..........................................3-4 3.2.2 MWD Integrated Area Study ....................................................3-5 3.2.2.1 IAS Process ...........................................................3-5 3.2.2.2 Summary of Conclusions.......................................3-7 3.2.2.3 Applicability to Western..........................................3-8 3.2.3 Drought Shortage Allocation ....................................................3-9 3.2.3.1 Applicability to Western..........................................3-9 3.3 One Water-One Watershed.................................................................3-9 Ten Pillars of Water Resource Management ....................................3-10 3.3.1 Applicability to Western..........................................................3-10 3.3.1.1 OWOW Goals ......................................................3-10 3.3.1.2 Planned Water Management Activities Relevant to Western ............................................3-11 3.4 Riverside County Integrated Plan......................................................3-13 Western MWD – IRWMP – May 2008 TOC-ii Table of Contents (cont'd) 3.4.1 Applicability to Western..........................................................3-13 3.4.1.1 Water Supply .......................................................3-13 3.4.1.2 Water Conservation .............................................3-14 3.4.1.3 The Watershed Approach....................................3-15 3.4.1.4 Water Quality .......................................................3-15 3.4.1.5 Groundwater Recharge .......................................3-15 3.4.1.6 Agricultural Resources.........................................3-16 3.4.1.7 Multi-Species Habitat Conservation Plan.............3-16 3.5 Riverside County Flood Control and Water Conservation District.....3-17 3.5.1 Applicability to Western..........................................................3-18 3.6 Upper Santa Ana River Watershed Integrated Regional Water Management Plan .............................................................................3-18 3.6.1 Applicability to Western..........................................................3-19 3.6.1.1 Upper Santa Ana River Watershed IRWM Plan Objectives and Water Management Strategies.............................................................3-19 3.6.1.2 Improve Water Supply Reliability.........................3-19 3.6.1.3 Protect and Enhance Water Quality.....................3-20 3.6.1.4 Ecosystem Restoration and Environmental Improvement........................................................3-20 3.6.1.5 Upper Santa Ana River Watershed IRWMP Benefits................................................................3-21 3.7 Other Regional Planning Efforts........................................................3-21 3.7.1 Chino Basin Planning.............................................................3-21 3.7.1.1 Chino Basin Optimum Basin Management Plan......................................................................3-21 3.7.1.2 Chino Basin Desalter Authority............................3-23 3.7.2 Santa Margarita Watershed Management Plan .....................3-23 3.7.3 Southern California Comprehensive Water Reclamation and Reuse Study...................................................................3-24