declaration, it is at the discretion of the Board to implement specific water shortage restrictions, prohibitions, and demand management measures (DMM). 3.1 Imported Water Shortage An imported water supply shortage represents one of the main causes of a potential supply shortage for IRWD. Metropolitan is responsible for importing water into the region through its contract with the State of California for SWP supplies and its operation of the CRA. Both sources are blended at Metropolitan’s Diemer and Weymouth Water Treatment Plants and then distributed to member agencies. Metropolitan uses its Water Surplus and Drought Management (WSDM) Plan, Integrated Water Resources Plan (IRP), and Long-Term Conservation Plan to guide its planning, operations, and water management during both shortage and surplus conditions. In times of shortage, Metropolitan’s Board may activate its Water Supply Allocation Plan (WSAP) based on its estimate and forecast of supplies, demands, and reserve levels. If forecasted supplies and demands are determined to put pressure on Metropolitan’s storage reserves, Metropolitan’s Board may decide to limit the availability of water by implementing its WSAP. The Metropolitan WSAP has 10 levels of water supply allocations, each corresponding to an additional 5 percent reduction of supply. Under Metropolitan’s Regional Shortage Levels shown in Table 3-2 , IRWD’s retail level reliability is high due to IRWD’s lower dependency on imported Metropolitan supplies and additional credits and adjustments (primarily from the retail impact adjustment and demand hardening credit). IRWD’s retail level reliability (excluding recycled water) remains substantially reliable at a Regional Shortage Level 10, and Metropolitan’s WSAP allocations can be supplemented with water supplies from IRWD’s Water Banking Program or from pumping above OCWD’s BPP. If Metropolitan implements its WSAP, then supplies stored in IRWD’s Water Banking Program qualify as an “extraordinary supply” and IRWD may take delivery of that supply through Metropolitan’s system, which increases IRWD’s WSAP allocation from Metropolitan. IRWD would not experience shortage gaps in any IRWD stages with the use of its water banking supplies combined with increased conservation. Table 3-2 assumes normal levels of local hydrology.
WSCP - 26
IRWD – 2025 Water Shortage Contingency Plan
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