Item 28 - Urban Water Management Plan and Water Shortage Contingency Plan

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Santa Ana 2020 Water Shortage Contingency Plan 2-5 2.3 Relationship with Wholesaler Water Shortage Planning The WSCP is designed to be consistent with MET’s Water Shortage and Demand Management (WSDM) Plan and Water Supply Allocation Plan (WSAP), and other emergency planning efforts as described below. MET’s WSAP is integral to the WSCP’s shortage response strategy in the event that MET determines that supply augmentation (including storage) and lesser demand reduction measures would not be sufficient to meet a projected shortage levels needed to meet demands. 2.3.1 MET Water Surplus and Drought Management Plan MET evaluates the level of supplies available and existing levels of water in storage to determine the appropriate management stage annually. Each stage is associated with specific resource management actions to avoid extreme shortages to the extent possible and minimize adverse impacts to retail customers should an extreme shortage occur. The sequencing outlined in the WSDM Plan reflects anticipated responses towards MET’s existing and expected resource mix. Surplus stages occur when net annual deliveries can be made to water storage programs. Under the WSDM Plan, there are four surplus management stages that provides a framework for actions to take for surplus supplies. Deliveries in Diamond Valley Lake (DVL) and in SWP terminal reservoirs continue through each surplus stage provided there is available storage capacity. Withdrawals from DVL for regulatory purposes or to meet seasonal demands may occur in any stage. The WSDM Plan distinguishes between shortages, severe shortages, and extreme shortages. The differences between each term are listed below.  Shortage: MET can meet full-service demands and partially meet or fully meet interruptible demands using stored water or water transfers as necessary.  Severe Shortage: MET can meet full-service demands only by using stored water, transfers, and possibly calling for extraordinary conservation.  Extreme Shortage: MET must allocate available supply to full-service customers. There are six shortage management stages to guide resource management activities. These stages are defined by shortfalls in imported supply and water balances in MET’s storage programs. When MET must make net withdrawals from storage to meet demands, it is considered to be in a shortage condition. Figure 2-3 gives a summary of actions under each surplus and shortage stages when an allocation plan is necessary to enforce mandatory cutbacks. The goal of the WSDM plan is to avoid Stage 6, an extreme shortage (MET, 1999).