IRWD’s resulting supply and demand comparisons in DWR Table 7-2 (A and B) , DWR Table 7-3 (A and B) , and DWR Table 7-4 (A and B) show varying levels of excess supplies over demands. The excess supplies are expected to be available for IRWD to serve as a buffer against variations in demand projections, future changes in land use, or modifications in supply availability. IRWD’s diverse water portfolio as described in Section 6 also provides for redundancy in both its potable and non-potable water supply systems. As previously stated, these projections do not consider supplemental supplies stored in IRWD’s Water Banking Program that would also be available for use during a shortage due to extended drought or major supply interruptions. 7.2 Water Service Reliability Assessment A. Imported Water Metropolitan, the regional wholesale agency for Southern California, manages the imported water supplies delivered to IRWD. Metropolitan’s policies and practices that maximize the efficient use of supplies are addressed in Metropolitan 's 2025 UWMP and Integrated Resource Plan (IRP) Update. Details of the regional coordination and operation of the water supply during a drought are included in Metropolitan's 2025 UWMP. MWDOC, a member agency of Metropolitan, addresses in its UWMP how imported water shortages from Metropolitan would be implemented in Orange County. Both Metropolitan and MWDOC’s 2025 UWMPs describe in detail the assessment and summary of imported water service reliability outlook through 2050. Metropolitan finds that it has supply capabilities sufficient to meet expected demands from 2030 through 2050 in a normal year condition, under a single dry-year condition, and in a period of drought lasting five consecutive water years. IRWD has made conservative estimates of annual imported supplies based on connected imported water delivery capacity from historical use evaluations and based on Metropolitan’s stated reliability through 2050. Additionally, IRWD can also recover and deliver supplemental water stored in its Water Banking Programs in Kern County, California, to IRWD’s service area under a short-term Metropolitan water supply allocation and major supply interruptions. B. Groundwater Supply Discussed further in Section 6, the Orange County Water District (OCWD) has made substantial investment in facilities, basin management and water rights protection. OCWD continues to develop new replenishment supplies, recharge capacity and basin protection measures to meet projected production from the Basin during normal and drought periods. Replenishment supplies for the Basin include capture of increasing Santa Ana River flows, purified recycled water, purchases of replenishment water from Metropolitan, and expansion of local supplies. Variations in local hydrology are the most significant impact to supplies of water available to recharge the groundwater basin. With the implementation of OCWD’s Groundwater Replenishment System (GWRS), a recycled water purification system, OCWD has a drought- proof replenishment supply. Sewage collected from the Orange County Sanitation District is treated and then purified using a three-step process to produce high-quality water used to recharge the Basin and for injection into the seawater intrusion barrier. The GWRS has been in
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IRWD – 2025 Urban Water Management Plan
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