Nancy Clemm and Kennedy/Jenks Consultants 2775 North Ventura Road, Suite 100 Oxnard, California 93036 805-973-5700 FAX: 805-973-1440 Final Report 2017 Water Supply Reliability Plan Update November 1, 2017 Prepared for Castaic Lake Water Agency 27234 Bouquet Canyon Road Santa Clarita, California 91350-2173 K/J Project No. 1744209*00 [This page intentionally left blank.] Table of Contents List of Tables .............................................................................................................................. iii List of Figures............................................................................................................................. iii List of Appendices ...................................................................................................................... iv Acronym List .............................................................................................................................. iv Executive Summary ..................................................................................................................... i Section 1: Introduction .............................................................................. 1-1 1.1 Background ....................................................................................... 1-1 1.1.1 CLWA Water Supply Reliability Plans .................................... 1-2 1.1.2 Summary of 2011 Plan and Recommendations for Implementation ...................................................................... 1-2 1.2 Authorization ..................................................................................... 1-3 1.2.1 Scope of Services .................................................................. 1-3 1.2.2 Conduct of Study .................................................................... 1-4 1.2.3 Comparison with 2011 Plan.................................................... 1-4 Section 2: Water Supplies and Demands ................................................... 2-1 2.1 Existing and Planned Water Supplies ................................................ 2-1 2.1.1 Imported Water Supplies – SWP ............................................ 2-4 2.1.1.1 SWP Facilities ...................................................... 2-4 2.1.1.2 SWP Contract Water Supply Provisions ............... 2-4 2.1.1.3 Factors Affecting SWP Table A Supplies .............. 2-6 2.1.1.4 SWP Table A Supply Assessment ........................ 2-7 2.1.2 Other Imported Supplies ........................................................ 2-9 2.1.2.1 Buena Vista-Rosedale Rio Bravo ......................... 2-9 2.1.2.2 Nickel Water - Newhall Land ................................ 2-9 2.1.2.3 Yuba Accord Water .............................................. 2-9 2.1.3 Groundwater ........................................................................ 2-10 2.1.3.1 Santa Clara River Groundwater Basin – East Subbasin ............................................................ 2-10 2.1.3.2 Adopted Groundwater Management Plan ........... 2-10 2.1.3.3 Groundwater Operating Plan .............................. 2-11 2.1.3.4 Alluvium ............................................................. 2-15 2.1.3.5 Saugus Formation .............................................. 2-15 2.1.3.6 Groundwater Supply Assessment ...................... 2-16 2.1.4 Recycled Water .................................................................... 2-18 2.1.4.1 Existing and Future Wastewater Treatment Facilities ............................................................. 2-19 Final Report – CLWA Water Supply Reliability Plan Update 2017 i Table of Contents (cont’d) 2.1.4.2 Additional Considerations Relating to the Use of Recycled Water .............................................. 2-20 2.1.5 Groundwater Banking and Exchange Programs ................... 2-21 2.1.5.1 Semitropic Banking Program .............................. 2-22 2.1.5.2 Rosedale-Rio Bravo Banking Program ............... 2-22 2.1.5.3 Semitropic Banking Program – Newhall Land ..... 2-23 2.1.5.4 Other (Planned) Banking .................................... 2-23 2.1.5.5 RRWBWD and West Kern Water Exchanges ..... 2-23 2.2 Existing and Projected Water Demands .......................................... 2-24 Section 3: Water Supply Reliability Analysis ............................................. 3-1 3.1 Water Operations Model ................................................................... 3-1 3.1.1 General Methodology ............................................................. 3-1 3.1.2 Hydrologic Variability .............................................................. 3-2 3.1.3 Reliability Determination ......................................................... 3-4 3.1.4 Interpretation of Water Operations Model Results .................. 3-4 3.2 Scenarios Analyzed .......................................................................... 3-7 3.2.1 Scenario Descriptions ............................................................ 3-7 3.2.2 Scenario Assumptions ............................................................ 3-8 3.3 Analysis Results .............................................................................. 3-13 3.3.1 Initial Reliability Results ........................................................ 3-13 3.3.2 Additional Supply Needs ...................................................... 3-18 3.3.2.1 Amount and Timing of Needs ............................. 3-18 3.3.2.2 Additional Supplies Considered .......................... 3-19 3.3.2.3 Assessment of Initial Supply Use ....................... 3-20 3.3.2.4 Supplies Selected for Evaluation ........................ 3-25 3.3.3 Reliability with Additional Supplies ....................................... 3-26 Section 4: Physical Reliability Considerations .......................................... 4-1 4.1 Physical Reliability ............................................................................ 4-1 4.2 Physical Constraints .......................................................................... 4-1 4.2.1 Local Infrastructure Constraints .............................................. 4-1 4.2.1.1 Identified Vulnerabilities........................................ 4-1 4.2.2 SWP Conveyance Constraints ............................................... 4-2 4.3 Catastrophic Interruption – Potential Outage Scenarios .................... 4-3 4.3.1 SWP Emergency Outage Scenarios ....................................... 4-4 4.3.1.1 Scenario 1: Emergency Freshwater Pathway ....... 4-6 4.3.1.2 Scenario 2: Complete Disruption of the California Aqueduct in the San Joaquin Valley ................................................................... 4-7 4.3.1.3 Scenario 3: Complete Disruption of the West Branch of the California Aqueduct ........................ 4-7 4.3.1.4 Assessment of Worst-Case Scenario ................... 4-8 Final Report – CLWA Water Supply Reliability Plan Update 2017 ii Table of Contents (cont’d) 4.4 Recommendations for Extended Outage Emergency Storage ......... 4-12 4.5 Recommendations for Short-Term Emergency and Operational Storage ........................................................................................... 4-13 Section 5: Reliability Recommendations ................................................... 5-1 5.1 Summary of Supply Reliability Analysis ............................................. 5-1 5.2 Summary of Physical Reliability Considerations ................................ 5-3 5.3 Recommendations ............................................................................ 5-4 References ................................................................................................................................... i List of Tables 2-1 CLWA’s Current and Planned Water Supplies and Banking Programs 2-2 Groundwater Operating Plan for the Santa Clarita Valley 2-3 Average/Normal Year Existing and Planned Groundwater Usage 2-4 Average/Normal Year Existing and Planned Recycled Water Usage 2-5 Normal Year SBX7-7 Demands 3-1 Scenario Assumption Summary 4-1 Projected Supplies and Demands During Six Month Disruption of Imported Supply 4-2 Emergency and Operational Storage Study Results 5-1 Summary of Supply Reliability Results List of Figures 2-1 SWP Table A Supply Reliability 2-2 Alluvial Aquifer Supply Reliability 2-3 Saugus Formation Supply Reliability 3-1 Interpretation of Model Results 3-2 Form of Model Results Presented 3-3 SWP Table A Supply Reliability 3-4 Summary of Initial Reliability 3-5 Base Scenario Reliability 3-6 Scenario A Reliability 3-7 Scenario B Reliability 3-8 Scenario C Initial Reliability Final Report – CLWA Water Supply Reliability Plan Update 2017 iii Table of Contents (cont'd) 3-9 Scenario C Initial Reliability: Detail of Supply Shortfall 3-10 Scenario C Initial Reliability: Average Annual Supply Surplus and Shortfall 3-11 Scenario C Initial Reliability: Total Banking and Exchange Program Storage 3-12 Scenario C Initial Reliability: SWP Flexible Storage 3-13 Scenario C Initial Reliability: Semitropic Bank Storage 3-14 Scenario C Initial Reliability: Rosedale-Rio Bravo Bank Storage 3-15 Scenario C Reliability with Additional Supplies 3-16 Scenario C Reliability with Additional Supplies: Detail of Supply Shortfall 3-17 Scenario C: Total Banking Program Storage Comparison 3-18 Summary of Reliability with Additional Supplies 4-1 Primary SWP Facilities 4-2 Emergency Storage Areas List of Appendices A CLWA Water Operations Model Description B Climate Change Groundwater Assessment Memorandum