Metropolitan—not the individual member agency—and for most member agencies, the blend varies from month-to-month and year-to-year due to hydrology, operational constraints, use of storage and other factors.
Colorado River Programs
As a regional cooperative of member agencies, Metropolitan invests in programs to ensure the continued reliability and sustainability of Colorado River supplies. Metropolitan was established to obtain an allotment of Colorado River water, and its first mission was to construct and operate the Colorado River Aqueduct (CRA). The CRA consists of five pumping plants, 450 miles of high voltage power lines, one electric substation, four regulating reservoirs, and 242 miles of aqueducts, siphons, canals, conduits and pipelines terminating at Lake Mathews in Riverside County. Metropolitan owns, operates, and manages the CRA. Metropolitan is responsible for operating, maintaining, rehabilitating, and repairing the CRA, and is responsible for obtaining and scheduling energy resources adequate to power pumps at the CRA’s five pumping stations. Colorado River supplies include Metropolitan’s basic Colorado River apportionment, along with supplies that result from existing and committed programs, including supplies from the Imperial Irrigation District-Metropolitan Conservation Program, the implementation of the Quantification Settlement Agreement (QSA) and related agreements, and the exchange agreement with San Diego County Water Authority. The QSA established the baseline water use for each of the agreement parties and facilitates the transfer of water from agricultural agencies to urban uses. Since the QSA, additional programs have been implemented to increase Metropolitan’s CRA supplies. These include the Palo Verde Irrigation District Land Management, Crop Rotation, and Water Supply Program, as well as the Lower Colorado River Water Supply Project. The 2007 Interim Guidelines provided for the coordinated operation of Lake Powell and Lake Mead, as well as the Intentionally Created Surplus program that allows Metropolitan to store water in Lake Mead. In May 2024, the United States Bureau of Reclamation issued a Record of Decision on its Supplement to the 2007 Interim Guidelines. Several reservoir and water management decisional documents and agreements that govern the operation of Colorado River facilities and management of the Colorado River are scheduled to expire at the end of 2026. On January 9, 2026 the Bureau of Reclamation released a draft EIS analyzing post-2026 operational guidelines and strategies. The post-2026 process is a multi-year process that will identify a range of alternatives and determine operations for Lake Powell and Lake Mead and other water management actions for potentially decades into the future. There can be no assurance as to the content or timing of the final EIS or how future management actions and operations may impact Metropolitan.
Storage Investments/Facilities
Surface and groundwater storage are critical elements of Southern California’s water resources strategy and help Metropolitan reduce its reliance on the Delta. Because California experiences dramatic swings in weather and hydrology, storage is important to regulate those swings and mitigate possible supply shortages. Surface and groundwater storage provide a means of storing water during normal and wet years for later use during dry years, when imported supplies are limited.
Appendix B - 16
IRWD – 2025 Urban Water Management Plan – Reduced Delta Reliance
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