COACHELLA VALLEY WATER MANAGEMENT PLAN 2010 UPDATE Final Report January 2012 Prepared for: Coachella Valley Water District Steve Robbins General Manager-Chief Engineer Patti Reyes Planning and Special Program Manager Prepared by: MWH 618 Michillinda Ave., Suite 200 Arcadia, CA 91007 Water Consult 535 North Garfield Avenue Loveland, CO 80537 Table of Contents Section Name Page Number Executive Summary ................................................................................................................ ES-1 ES-1 The Coachella Valley ...............................................................................................ES-1 ES-2 Water Management in the Coachella Valley ...........................................................ES-3 ES-3 Current Condition of Coachella Valley Groundwater Basin ...................................ES-4 ES-4 The 2002 Water Management Plan..........................................................................ES-5 ES-4.1 Goals and Objectives ......................................................................................ES-5 ES-4.2 Accomplishments Since 2002 .........................................................................ES-6 ES-5 2010 WMP Update ................................................................................................ES-13 ES-5.1 Population and Water Demand .....................................................................ES-13 ES-5.2 Future Water Supply Needs ..........................................................................ES-16 ES-5.3 What is New in the 2010 WMP Update? ......................................................ES-18 ES-5.4 2010 WMP Update Elements........................................................................ES-19 ES-6 Water Quality Management ...................................................................................ES-25 ES-7 Monitoring and Data Management ........................................................................ES-25 ES-7.1 Water Quality ................................................................................................ES-26 ES-7.2 Subsidence ....................................................................................................ES-26 ES-7.3 Water Resources Database ............................................................................ES-26 ES-7.4 Groundwater Model Update and Recalibration ............................................ES-26 ES-7.5 Water Quality Model ....................................................................................ES-26 ES-7.6 Water Demand and Conservation Monitoring ..............................................ES-26 ES-8 Plan Costs...............................................................................................................ES-26 ES-9 Implementation and Implementation Costs ...........................................................ES-27 ES-10 Conclusion ..............................................................................................................ES-29 Section 1 Introduction ............................................................................................................... 1-1 1.1 Purpose and Need for Water Management Plan Update ........................................... 1-1 1.2 Study Area Description .............................................................................................. 1-3 1.3 Approach to the Plan Update ..................................................................................... 1-5 1.4 Relationship to Other Planning Efforts ...................................................................... 1-6 1.4.1 Integrated Regional Water Management Plan .................................................. 1-6 1.4.2 Urban Water Management Plan ........................................................................ 1-6 1.4.3 Mission Creek and Garnet Hill Water Management Plan ................................ 1-9 1.4.4 Coachella Valley Multiple Species Habitat Conservation Plan ........................ 1-9 1.5 Groundwater Management Planning Act................................................................. 1-10 1.6 Plan Adoption .......................................................................................................... 1-11 Section 2 The 2002 Water Management Plan ......................................................................... 2-1 2.1 Alternatives ................................................................................................................ 2-1 2.2 Recommended Plan ................................................................................................... 2-2 2.2.1 Water Conservation .......................................................................................... 2-2 2.2.2 Additional Water Supplies ................................................................................ 2-3 2.2.3 Source Substitution ........................................................................................... 2-4 Coachella Valley WMP 2010 Update Page i Table of Contents 2.2.4 Groundwater Recharge ..................................................................................... 2-4 2.3 Environmental Compliance ....................................................................................... 2-5 2.4 Water Management Plan Implementation Program ................................................... 2-6 2.5 Status of 2002 WMP Implementation........................................................................ 2-7 Section 3 Water Demand Projections ...................................................................................... 3-1 3.1 Factors Affecting Future Water Demands ................................................................. 3-1 3.1.1 Revised Growth Forecasts ................................................................................ 3-1 3.1.2 Land Use Changes ............................................................................................ 3-2 3.1.3 Development on Tribal Land ............................................................................ 3-2 3.1.4 Development Outside the 2002 WMP Study Area ........................................... 3-3 3.1.5 Effects of Recession on Growth Forecasts ....................................................... 3-4 3.2 Population and Land Use Forecasts ........................................................................... 3-4 3.2.1 Population Forecasts ......................................................................................... 3-4 3.2.2 Land Use Forecasts ........................................................................................... 3-5 3.3 Water Demand Projections ........................................................................................ 3-9 3.3.1 Assumptions ...................................................................................................... 3-9 3.3.1.1. Water Conservation .................................................................................... 3-9 3.3.1.2. Urban Water Demand Assumptions ........................................................... 3-9 3.3.1.3. Agricultural Water Demand Assumptions ................................................ 3-10 3.3.1.4. Golf Course Water Demand Assumptions ................................................ 3-10 3.3.1.5. Fish Farm and Duck Club Water Demand Assumptions .......................... 3-11 3.3.1.6. Tribal Demand Assumptions .................................................................... 3-11 3.3.2 Water Demand Projections ............................................................................. 3-11 3.4 Demand Uncertainty ................................................................................................ 3-11 Section 4 Existing Water Supplies ............................................................................................ 4-1 4.1 Local Groundwater .................................................................................................... 4-1 4.1.1 Whitewater River Subbasin .............................................................................. 4-1 4.1.2 Mission Creek Subbasin ................................................................................... 4-6 4.1.3 Garnet Hill Subbasin ......................................................................................... 4-6 4.1.4 Desert Hot Springs Subbasin ............................................................................ 4-7 4.1.5 Historical Groundwater Use ............................................................................. 4-7 4.1.6 Overdraft Status ................................................................................................ 4-8 4.2 Colorado River ......................................................................................................... 4-13 4.2.1 Quantification Settlement Agreement............................................................. 4-15 4.3 State Water Project (SWP)....................................................................................... 4-16 4.3.1 Metropolitan 100,000 AFY Transfer .............................................................. 4-17 4.3.2 Other SWP Transfers ...................................................................................... 4-18 4.3.3 SWP Deliveries ............................................................................................... 4-18 4.3.4 SWP Delivery Reliability ............................................................................... 4-20