Draft Casitas Municipal Water District Comprehensive Water Resources
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DRAFT CASITAS MUNICIPAL WATER DISTRICT COMPREHENSIVE WATER RESOURCES PLAN (CWRP) JUNE 8, 2020 Prepared by Stantec Table of Contents TABLE OF CONTENTS ............................................................................................................ II LIST OF TABLES ......................................................................................................................III LIST OF FIGURES ....................................................................................................................III LIST OF APPENDICES ............................................................................................................. V ABBREVIATIONS .................................................................................................................... VI DEFINITIONS .......................................................................................................................... VII EXECUTIVE SUMMARY ........................................................................................................... 9 SECTION 1 INTRODUCTION ..........................................................................................14 1.1 THE CASITAS SYSTEM ...............................................................................................14 1.2 PROJECT OBJECTIVES AND DRIVERS .....................................................................15 1.3 OVERVIEW OF THE CWRP PROCESS .......................................................................16 SECTION 2 STAKEHOLDER INVOLVEMENT ...............................................................18 SECTION 3 DEMAND ANALYSIS ..................................................................................20 3.1 CASITAS WATER SYSTEM FUTURE DEMANDS ........................................................21 3.2 OJAI WATER SYSTEM FUTURE DEMANDS ...............................................................22 3.3 CWRP DEMAND SUMMARY ........................................................................................22 SECTION 4 WATER SUPPLY ANALYSIS ......................................................................24 4.1 CASITAS SYSTEM WATER SUPPLY ANALYSIS.........................................................24 4.1.1 Casitas Yield Model Update ......................................................................... 26 4.1.2 Incorporation of the WEAP Policy and the Concept of Safe Demand ........... 26 4.1.3 Minimum Allowable Storage Level in Lake Casitas ...................................... 27 4.1.4 Climate Variability and Climate Change Analysis ......................................... 28 4.1.5 Reliability Analysis ....................................................................................... 30 4.2 WATER SUPPLY NEEDS ANALYSIS ...........................................................................30 4.2.1 Water Supply Gap Analysis .......................................................................... 31 4.2.2 Immediate Risk of Shortages ....................................................................... 32 4.2.3 Portfolio Diversification ................................................................................. 33 4.2.4 Water Supply Planning Goals ....................................................................... 34 SECTION 5 WATER SUPPLY OPTIONS ANALYSIS .....................................................35 5.1 WATER SUPPLY OPTIONS CONSIDERED .................................................................35 5.2 WATER SUPPLY OPTIONS SCREENING ...................................................................37 5.3 LOCAL WATER SUPPLY OPTIONS .............................................................................38 5.4 SUPPLEMENTAL WATER SUPPLY OPTIONS ............................................................44 5.4.1 State Water Project Overview ...................................................................... 44 5.4.2 Casitas State Water Project Options ............................................................ 47 SECTION 6 PORTFOLIO DEVELOPMENT AND RANKING ..........................................53 SECTION 7 RECOMMENDED PLAN ..............................................................................54 7.1 PLANNING POLICIES ...................................................................................................54 7.2 PORTFOLIO OF PROJECTS ........................................................................................55 7.2.1 Meet Long-Term Supply Gap of 5,200 AFY .................................................. 56 7.2.2 Meet Short-Term Risk Mitigation of 2,500 AFY ............................................ 56 7.2.3 Portfolio Diversification ................................................................................. 56 7.2.4 Adaptive Management with Conditional Options .......................................... 57 7.2.5 Summary of Recommended Portfolio ........................................................... 58 7.2.6 Verification of Recommended Portfolio ........................................................ 58 7.3 NEW AND UPDATED PROGRAMS ..............................................................................60 7.3.1 Water Conservation Plan ............................................................................. 60 7.3.2 Updated Water Efficiency and Allocation Program ....................................... 61 7.3.3 Supplemental Water Integration Plan ........................................................... 62 7.4 STAKEHOLDER FEEDBACK ADDRESSED IN THE PLAN ..........................................63 SECTION 8 IMPLEMENTATION OF RECOMMENDED PLAN .......................................65 8.1 COST ESTIMATES FOR RECOMMENDED WATER SUPPLY OPTIONS ....................65 8.2 PHASED PORTFOLIO IMPLEMENTATION ..................................................................65 SECTION 9 REFERENCES ............................................................................................69 List of Tables Table 3-1: Summary of Future Water Demands Adopted for CWRP ......................................................... 23 Table 4-1: Lake Casitas Safe Demand (AFY) ................................................................................................ 30 Table 4-2: Summary of Water Supply Gap Analysis ................................................................................... 32 Table 5-1: Decision Support Tool Criteria and Weights for Evaluating Water Supply Options .................. 37 Table 5-2: Summary of Local Options Carried forward to Portfolio Analyses ............................................ 39 Table 5-3: Summary of Supplemental Water Options Carried Forward to Portfolio Analyses .................. 48 Table 7-1: Stakeholder Issues Proposed Resolutions per the CWRP .......................................................... 63 Table 8-1: Capital Costs of Project Options in the Recommended Portfolio ............................................. 65 Table 8-2: Overall Implementation Timeline for Recommended Plan ....................................................... 66 List of Figures Figure 1-1: CWRP Links Water Supply Needs and Solutions ...................................................................... 14 Figure 1-2. Casitas Water System Overview ............................................................................................... 15 Figure 1-3: Drivers for Preparing the Comprehensive Water Resources Plan ........................................... 15 Figure 1-4: Overview of the CWRP Process ................................................................................................ 17 Figure 3-1: Connection Between Casitas Sources and Demand Centers ................................................... 20 Figure 3-2: Method for Estimating Future Demand for CWRP ................................................................... 21 Figure 3-3: Casitas System Historical Water Production and 2040 Water Demand Forecast .................... 21 Figure 3-4: Ojai Water System Historical Water Production and 2040 Water Demand Forecast .............. 22 Figure 4-1. Schematic representation of Lake Casitas Yield Model setting ................................................ 25 Figure 4-2: Impact of 2019 Updates on Lake Casitas Yield Model Safe Yield Estimates for Historical Hydrologic Data ........................................................................................................................................... 26 Figure 4-3: Lake Casitas WEAP Stages ........................................................................................................ 27 Figure 4-4: Minimum Allowable Lake Level ................................................................................................ 28 Figure 4-5: Plot of 100 74-year Monthly Time Series for Ventura River Streamflow at Robles Diversion, Based on Historical Record ......................................................................................................................... 28 Figure 4-6: Lake Casitas Safe Yield for Synthetic Hydrologic Sequences .................................................... 29 Figure 4-7: Lake Casitas Safe Demand Exceedance Probability Analysis .................................................... 30 Figure 4-8: Casitas System Water Supply Gap ............................................................................................ 31 Figure 4-9: Ojai Water System Water Supply Gap ...................................................................................... 31 Figure