Section 3 – Six Standard Shortage Stages
LAW Six standard water shortage levels are established by law in the CWC as follows:
Water Code Section 10632(a)(3)
(A) Six standard water shortage levels corresponding to progressive ranges of up to 10, 20, 30, 40, and 50 percent shortages and greater than 50 percent shortage. Urban water suppliers shall define these shortage levels based on the suppliers’ water supply conditions, including percentage reductions in water supply, changes in groundwater levels, changes in surface elevation or level of subsidence, or other changes in hydrological or other local conditions indicative of the water supply available for use. Shortage levels shall also apply to catastrophic interruption of water supplies, including, but not limited to, a regional power outage, an earthquake, and other potential emergency events. (B) An urban water supplier with an existing water shortage contingency plan that uses different water shortage levels may comply with the requirement in subparagraph (A) by developing and including a cross-reference relating its existing categories to the six standard water shortage levels.
The WSCP provides guidelines for responses to varying levels of supply shortages in the six standard shortage levels established by the CWC. The WSCP includes actions that can be implemented to reduce demands down to specific levels in accordance with reduced supply availability. The levels of action identified in the WSCP are shown in Table 3-1 . Table 3 - 1: Shortage Levels in Water Shortage Contingency Plan
IRWD Shortage Level
Percent Supply Reduction
Water Supply Condition
Level 1
0% - 10%
Shortage Warning
Level 2
11% to 20%
Significant Shortage
Level 3
21% to 30%
Severe Shortage
Level 4
31% to 40%
Severe Shortage
Level 5
41% to 50%
Crisis Shortage
Level 6
50% +
Crisis Shortage
Levels or stages of the WSCP are declared at the discretion of IRWD’s Board depending on the level and duration of the water shortage. The Board evaluates water supply conditions and, if it determines that a shortage exists, declares the corresponding level of the WSCP. As part of the
WSCP - 25
IRWD – 2025 Water Shortage Contingency Plan
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