2019 Santa Clarita Valley Water Report Santa Clarita Valley Water Agency Los Angeles County Waterworks District 36 July 2020 2019 Santa Clarita Valley Water Report prepared for: Santa Clarita Valley Water Agency Los Angeles County Waterworks District 36 July 2020 prepared by: William L. Halligan, PG Lisa Lavagnino, GIT Senior Principal Hydrogeologist Project Geologist Table of Contents Executive Summary ............................................................................... ES-1 ES.1 2019 Water Requirements & Supplies .................................................................... ES-1 ES.2 Groundwater........................................................................................................... ES-1 ES.3 I mported Water Supplies ........................................................................................ ES-3 ES.4 2020 Watter Supply Outlook .................................................................................. ES-4 ES.5 Water Supply Conservation .................................................................................... ES-5 1 - Introduction.......................................................................................... 1 1.1 Background ....................................................................................................................1 1.2 Purpose and Scope of the Report ..................................................................................3 1.3 Santa Clarita Valley Water Divisions and LACWD 36 .....................................................3 1.4 The Upper Santa Clara River Hydrologic Area and East Groundwater Subbasin ........................................................................................................................4 2 - 2019 Water Supplies and Use ............................................................ 10 2.1 2019 Water Supplies ....................................................................................................10 2.2 Historical Water Use Trends ........................................................................................11 2.3 Municipal Water Use ...................................................................................................13 2.4 Agricultural and Other Water Uses..............................................................................14 3 - Water Supplies ................................................................................... 15 3.1 Groundwater Basin Yield ............................................................................................15 3.2 Alluvium – General ......................................................................................................18 3.3 Saugus Formation – General .......................................................................................28 3.4 Imported Water Supplies.............................................................................................32 3.5 Other Water Sources ..................................................................................................37 3.6 Water Quality ..............................................................................................................38 3.7 Santa Clara River ..........................................................................................................45 4 - Summary 0f 2019 Water Supply and 2020 Outlook ........................... 50 4.1 2019 Water Demand ...................................................................................................50 4.2 Projected 2020 Water Demand and Supplies ..............................................................50 4.3 Supplemental Water Supply Sources ...........................................................................53 4.4 Water Supply Reliability...............................................................................................53 4.5 Water Supply Strategy .................................................................................................54 5 - Water Conservation ............................................................................ 56 5.1 Recent Conservation Efforts ........................................................................................56 5.2 2019 Water Use ...........................................................................................................57 6 - References .......................................................................................... 61 Appendix A: Historical Water Supply and Utilization Tables for Municipal and Agricultural/Other Users List of Tables Table ES-1: Santa Clarita Valley Summary of 2019 Water Supplies and Uses (af).......................................ES-1 Table 2-1: Summary of 2019 Water Supplies and Uses (af) ...........................................................................10 Table 2-2: Total Water Supply Utilization (af) .................................................................................................12 Table 2-3: Municipal Water Supply Utilization and Service Connections .......................................................13 Table 2-4: Water Supply Utilization by Agricultural and Other Users ............................................................14 Table 3-1: Groundwater Operating Plan for the Santa Clarita Valley .............................................................17 Table 3-2 2019 SCVWA Imported Water Supply and Disposition (af) ...........................................................35 Table 4-1 2020 Water Demand and Water Resources (acre-feet) ..................................................................52 Table 5-1: 20x2020 Compliance GPCD Targets and current levels .................................................................57 List of Figures Figure 1-1: SCV Water and LACWD 36 Service Areas .......................................................................................2 Figure 1-2: Upper Santa Clara River Hydrologic Area .......................................................................................5 Figure 1-3: Santa Clara River Valley Groundwater Basin and Subbasins ..........................................................6 Figure 1-4: Precipitation Gage Locations .........................................................................................................7 Figure 1-5: Annual Precipitation and Cumulative Departure from Mean Annual Precipitation at Newhall Fire Station #73 Gage ...................................................................................................9 Figure 2-1: Total Water Use by Sector ............................................................................................................10 Figure 2-2: Water Use by Source ....................................................................................................................10 Figure 2-3: Total Water Supply Utilization ......................................................................................................12 Figure 2-4: Service Connections and Municipal Water Use ...........................................................................13 Figure 3-1: Alluvium and Saugus Formation ..................................................................................................16 Figure 3-2: Groundwater Production – Alluvium ...........................................................................................21 Figure 3-3: Alluvial Well Locations by Area ....................................................................................................23 Figure 3-4: Groundwater Elevations in Eastern Santa Clarita Valley Alluvial Wells ........................................24 Figure 3-5: Groundwater Elevations in Western Santa Clarita Valley Alluvial Wells ......................................25 Figure 3-6: Annual Groundwater Production from Alluvium by Area (Acre-feet) ..........................................29 Figure 3-7: Saugus Formation Well Locations ................................................................................................30 Figure 3-8: Groundwater Production – Saugus Formation ............................................................................32 Figure 3-9: Groundwater Elevations in Saugus Wells .....................................................................................31 Figure 3-10: Treated Water Distribution System Santa Clarita Valley Water Agency .....................................33 Figure 3-11: Saugus Formation Monitoring Well Locations ...........................................................................40 Figure 3-12: Groundwater Quality in Eastern Santa Clarita Valley Alluvial Wells ...........................................42 Figure 3-13: Groundwater Quality in Western Santa Clarita Valley Alluvial Wells .........................................44 Figure 3-14: Groundwater Quality in Saugus Wells .......................................................................................46 Figure 3-15: Streamflow Discharge Gage Locations .......................................................................................48 Figure 3-16: Annual Stream Discharge............................................................................................................49 Figure 4-1: Historical and Projected Water Use .............................................................................................51 List of Abbreviations and Acronyms af acre-feet afy acre-feet per year Basin Santa Clara River Valley Groundwater Basin BMPs Best Management Practices