Table 3 - 2: Metropolitan WSAP and IRWD Shortage Levels
Regional Shortage Percentage
Retail Impact Adjustment Maximum
MWD Regional Shortage Level
IRWD Reliability
IRWD Shortage Level
Level 1 Level 2 Level 3 Level 4 Level 5 Level 6 Level 7 Level 8 Level 9 Level 10
5%
2.5% 5.0% 7.5%
100%
Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Level 1 Level 1
10% 15% 20% 25% 30% 35% 40% 45% 50%
99% 98% 97% 96% 95% 94% 93% 92% 90%
10.0% 12.5% 15.0% 17.5% 20.0% 22.5% 25.0%
3.2 Emergency Supplies IRWD’s Water Banking Program, which includes the existing IRWD Water Bank and IRWD’s share of the Kern Fan Project, provides an important water management tool to improve imported water reliability and protect IRWD customers during potential shortages. This source of supply is in addition to the supplies that are available to IRWD during non-shortage periods and is only used as “extraordinary supply” during shortages triggered by Metropolitan allocations or other conditions. Water banking is the practice of recharging water to underground storage aquifers during wet periods and recovering this water for later use. IRWD Policy Position for Water Banking, Transfers and Wheeling (April 2026) states that IRWD’s water banking program makes IRWD more resilient during major shortages. Generally, IRWD seeks to acquire cost-effective and diverse supplemental sources of water during wet hydrologic periods. IRWD also plans to acquire supplemental supplies through smaller, sustained, controllable and schedulable supply sources. IRWD’s water banking program is a cost effective environmentally sound method to store and recover supplemental water that could be called upon during drought conditions or supply interruptions. In the event of a major supply interruption, this water would be available to fulfill IRWD’s estimated needs for imported water over extended periods of time. IRWD’s Water Banking Program provides IRWD with the ability to store and recover this supplemental water to meet supply reliability requirements. The six identified shortage levels are prior to and independent of utilizing emergency supplies from IRWD’s Water Banking Program (IRWD Water Bank and Kern Fan Project). Table 3-3 identifies how each shortage level would be offset using water from the IRWD Water Banking
WSCP - 27
IRWD – 2025 Water Shortage Contingency Plan
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