Modesto Irrigation District – 2020 Agricultural Water Management Plan Update AGRICULTURAL WATER MANAGEMENT PLAN 2020 Update FOR THE MODESTO IRRIGATION DISTRICT Prepared Pursuant to Water Code Section 10826 Adopted March 23, 2021 1 Modesto Irrigation District – 2020 Agricultural Water Management Plan Update Table of Contents Section I: Introduction _________________________________________________________ 8 1. Description of Previous Water Management Activities _______________________________ 11 2. Coordination Activities _________________________________________________________ 16 a) Notification of AWMP Preparation _______________________________________________________ 16 b) Public Participation ___________________________________________________________________ 16 3. AWMP Adoption and Submittal _________________________________________________ 16 a) AWMP Adoption _____________________________________________________________________ 16 b) AWMP Submittal _____________________________________________________________________ 16 c) AWMP Availability ____________________________________________________________________ 16 4. AWMP Implementation Schedule ________________________________________________ 17 Section II: Description of the Modesto Irrigation District and Service Area ______________ 24 1. Physical Characteristics ________________________________________________________ 24 a) Size of the Service Area ________________________________________________________________ 24 b) Location of the Service Area and Water Management Facilities _______________________________ 28 c) Terrain and Soils _____________________________________________________________________ 31 d) Climate _____________________________________________________________________________ 32 2. Operational Characteristics _____________________________________________________ 33 a) Operating Rules and Regulations ________________________________________________________ 33 b) Water Delivery Measurements or Calculations _____________________________________________ 36 c) Water Rate Schedules and Billing ________________________________________________________ 37 d) Water Shortage Allocation Practices _____________________________________________________ 39 e) Drought Plan ________________________________________________________________________ 40 i) Drought Resilience Planning __________________________________________________________ 41 ii) Drought Response Planning __________________________________________________________ 43 Section III: Description of Quantity of Water Uses __________________________________ 47 1. Agricultural Water Use _________________________________________________________ 49 2. Environmental Water Use ______________________________________________________ 51 3. Recreational Water Use ________________________________________________________ 52 4. Municipal and Industrial Use ____________________________________________________ 52 5. Groundwater Recharge Use _____________________________________________________ 55 6. Transfer and Exchange Use _____________________________________________________ 56 7. Other Water Use _____________________________________________________________ 56 8. Projected Water Use __________________________________________________________ 57 Section IV: Description of Quantity and Quality of the Water Resources of the Modesto Irrigation District ____________________________________________________________ 58 1. Water Supply Quantity_________________________________________________________ 58 2 Modesto Irrigation District – 2020 Agricultural Water Management Plan Update a) Surface Water Supply _________________________________________________________________ 58 b) Groundwater Supply __________________________________________________________________ 58 c) Other Water Supplies _________________________________________________________________ 62 d) Drainage from the Water Supplier’s Surface Area ___________________________________________ 62 e) Water Supply Reliability _______________________________________________________________ 63 f) Future Water Supply __________________________________________________________________ 63 2. Water Supply Quality __________________________________________________________ 66 a) Surface Water Supply Quality ___________________________________________________________ 66 b) Groundwater Supply Quality ___________________________________________________________ 66 c) Other Water Supplies _________________________________________________________________ 67 d) Drainage from the Water Supplier’s Surface Area ___________________________________________ 67 3. Water Quality Monitoring Practices ______________________________________________ 67 a) Source Water ________________________________________________________________________ 67 b) Drainage Water ______________________________________________________________________ 68 Section V: Water Budget ______________________________________________________ 69 1. Quantifying the Modesto Irrigation District’s Water Supplies __________________________ 69 a) Modesto Irrigation District’s Water Quantities _____________________________________________ 69 b) Other Water Sources Quantities _________________________________________________________ 71 2. Quantification of Water Uses ___________________________________________________ 71 3. Annual Water Budget __________________________________________________________ 72 4. Identify Water Management Objectives ___________________________________________ 75 a) Volumetric Pricing Structure. Section II-2.c, ________________________________________________ 75 b) Water Shortage Allocation Policies. Section II-2.d, __________________________________________ 75 c) Conjunctive Management. Section VII-1, __________________________________________________ 75 d) System Efficiency Improvements. ________________________________________________________ 76 5. Quantify the Efficiency of Agricultural Water Use ___________________________________ 76 Section VI: Climate Change ____________________________________________________ 78 1. Effects of Climate Change on Water Supply ________________________________________ 78 2. Effects of Climate Change on Agriculture’s Water Demand ____________________________ 81 3. MID Response to Effects of Climate Change ________________________________________ 82 Section VII: Water Use Efficiency Information _____________________________________ 83 1. EWMP Implementation and Reporting ____________________________________________ 83 a) Water Use Efficiency Improvements _____________________________________________________ 83 b) Evaluation of Water Use Efficiency Improvements __________________________________________ 87 2. Documentation for Non-Implemented EWMPs _____________________________________ 91 Section VIII: Supporting Documentation __________________________________________ 93 1. Agricultural Water Measurement Regulation Documentation _________________________ 93 a) Introduction _________________________________________________________________________ 93 b) Existing Facilities and Measurement Practices _____________________________________________ 94 3 Modesto Irrigation District – 2020 Agricultural Water Management Plan Update c) Legal Certification and Apportionment Required for Water Measurement _______________________ 96 d) Engineer Certification and Apportionment Required for Water Measurement – Technically Infeasible 98 e) Description of Water Measurement Best Professional Practices _______________________________ 98 f) Documentation of Water Measurement Conversion to Volume ______________________________ 101 g) Device Corrective Action Plan Required for Water Measurement _____________________________ 101 i) Device Pilot Program ______________________________________________________________ 101 ii) Schedule ________________________________________________________________________ 113 iii) Finance Plan _____________________________________________________________________ 114 iv) Budget __________________________________________________________________________ 114 Section IX: References _______________________________________________________ 115 List of Figures Figure 1 – Location Map of MID and Stanislaus County ________________________________________________ 9 Figure 2 – MID Irrigation Service Area _____________________________________________________________ 27 Figure 3 – Annual Tuolumne River Computed Natural Flow and River Releases by MID Diversions and Don Pedro Storage _____________________________________________________________________________________ 48 Figure 4 – Modesto Groundwater Basin, Spring 1994 Groundwater Elevations, Unconfined Aquifer ____________ 54 Figure 5 – Modesto Groundwater Basin, Spring 2010 Groundwater Elevations, Unconfined Aquifer ____________ 54 Figure 6 – Critically Overdrafted Groundwater Basins _________________________________________________ 65 Figure 7 – Pilot Program Site Locations ___________________________________________________________ 105 Figure 8 – Preliminary Pilot Program Test Results ___________________________________________________ 110 List of Tables Table 1 – Summary of Coordination, Adoption and Submittal Activities __________________________________ 17 Table 2 – Tuolumne River Runoff 2015-2020 ________________________________________________________ 24 Table 3 – Water Supplier History and Size __________________________________________________________ 25 Table 4 – Expected Changes to Irrigation Service Area ________________________________________________