SUPPLEMENT TO THE WATER SUPPLY ASSESSMENT FOR LAKESIDE AT SUTTER POINTE OCTOBER 1, 2020 PREPARED BY [This page intentionally left blank] TABLE OF CONTENTS SECTION 1 THE SUTTER POINTE PROJECT ....................................................................................................... 1 1.1 Introduction to the Project ........................................................................................................ 1 1.2 Project Description .................................................................................................................... 3 1.3 Water Purveyor ......................................................................................................................... 5 1.4 Legal Requirements ................................................................................................................... 5 SECTION 2 HISTORY OF THE SUTTER POINTE LANDS ...................................................................................... 9 2.1 Overview of the Natomas Basin ................................................................................................ 9 2.2 Agricultural Development of the Natomas Basin ...................................................................... 9 2.3 Organization of Irrigation Water Deliveries ............................................................................ 14 2.4 Urban Development of the Natomas Basin ............................................................................. 18 2.5 The Natomas Basin Conservancy ............................................................................................. 21 2.6 Water Supplies in the Natomas Basin ..................................................................................... 23 2.7 Conversion of Use for Land and Water ................................................................................... 26 2.8 History of Water Use on Sutter Pointe Lands .......................................................................... 28 2.9 Conclusions .............................................................................................................................. 33 SECTION 3 WATER PLANNING FOR SUTTER POINTE .................................................................................... 35 3.1 Overview of Sutter Pointe ....................................................................................................... 35 3.2 Water Demands ....................................................................................................................... 35 3.3 Water Supplies ........................................................................................................................ 38 3.4 North American Subbasin ........................................................................................................ 41 3.5 Sacramento River .................................................................................................................... 41 3.6 Conclusions .............................................................................................................................. 42 SECTION 4 PROJECT WATER DEMANDS ........................................................................................................ 43 4.1 Water Demand Factors ............................................................................................................ 43 4.2 Project Water Demands .......................................................................................................... 44 4.3 Water Use Efficiency................................................................................................................ 45 4.4 Demand Variance by Hydrologic Conditions ........................................................................... 53 4.5 Climate of the Project Area ..................................................................................................... 54 4.6 Use of Recycled Water ............................................................................................................ 55 SECTION 5 GROUNDWATER SUPPLIES .......................................................................................................... 57 5.1 The North American Subbasin ................................................................................................. 57 Supplement to the Water Supply Assessment for Lakeside at Sutter Pointe Page i 5.2 Models of the Subbasin ........................................................................................................... 60 5.3 Groundwater Recharge and Elevation .................................................................................... 62 5.4 Management of the Subbasin ................................................................................................. 67 5.5 Use of Groundwater for Sutter Pointe .................................................................................... 72 5.6 Conclusions .............................................................................................................................. 75 SECTION 6 SACRAMENTO RIVER SUPPLIES ................................................................................................... 77 6.1 The Sacramento River .............................................................................................................. 77 6.2 Natomas Central Mutual Water Company .............................................................................. 77 6.3 Water Deliveries Under the WSA ............................................................................................ 86 6.4 Water Wholesale Agreement .................................................................................................. 87 6.5 Regulatory Approvals .............................................................................................................. 89 6.6 Conclusions .............................................................................................................................. 90 SECTION 7 ASSESSMENT OF WATER SUPPLIES ............................................................................................. 93 7.1 Water Supplies for the Project ................................................................................................ 93 7.2 Water Supplies for Sutter Pointe ............................................................................................. 94 SECTION 8 REFERENCES ................................................................................................................................. 97 Page ii October 1, 2020 Tables Table 1. Acreage of land uses in the Project ......................................................................................................... 3 Table 2. Crops grown within Natomas mutual water companies by acreage, 1929 .......................................... 13 Table 3. Acreage of Natomas mutual water companies, 1929 ........................................................................... 17 Table 4. Water supplies in the Natomas Basin, 2004 ......................................................................................... 24 Table 5. Land uses in Sutter Pointe ..................................................................................................................... 28 Table 6. Water uses on Sutter Pointe lands, 2004 .............................................................................................. 29 Table 7. Prior studies of groundwater use in the Natomas Basin ...................................................................... 32 Table 8. Water uses on Sutter Pointe lands during 2010s .................................................................................. 32 Table 9. Water uses on Project lands during 2010s ............................................................................................ 33 Table 10. Historical water supplies used on Sutter Pointe and Project lands .................................................... 33 Table 11. Acreage of land uses in Sutter Pointe ................................................................................................. 36 Table 12. Land use water demand factors for Sutter Pointe .............................................................................. 36 Table 13. Water demands for Sutter Pointe ....................................................................................................... 37 Table 14. Water supply programs for Sutter Pointe ........................................................................................... 38 Table 15. Land use water demand factors for the Project ................................................................................. 43 Table 16. Water demands for the Project .......................................................................................................... 44 Table 17. NCMWC distribution systems ............................................................................................................. 78 Table 18. Riparian acreage in the Natomas mutual water companies, 1958 ..................................................... 79 Table 19. NCMWC appropriative water rights before the SWRCB ..................................................................... 79 Table 20. NCMWC diversion rights (AF) in the Settlement Contract .................................................................. 81 Figures Figure 1. Location of Sutter Pointe and the Project ............................................................................................