Deliveries of Conserved Colorado River Water Secured Through 2047

June 25, 2018

The San Diego region will benefit from a historic water conservation-and-transfer agreement with the Imperial Irrigation District at least through 2047 after the San Diego County Water Authority’s Board of Directors took action Dec. 7 to ensure deliveries of those supplies for an additional decade.


The Water Authority’s independent Colorado River water supplies are delivered through the Colorado River Aqueduct. The Water Authority is assessing potential pipeline and tunnel alignments that could move these supplies from Imperial Dam to San Vicente Reservoir.

The Board voted unanimously to extend an Exchange Agreement with the Metropolitan Water District of Southern California by 10 years, requiring MWD to continue transporting conserved IID water to San Diego County through 2047. This year, about 20 percent of the San Diego region’s water is from the Water Authority’s conservation-and-transfer agreement with IID, and the volumes will continue to grow until 2021.

By extending the Exchange Agreement with MWD, the Water Authority gains 2 million acre-feet of conserved Colorado River water for delivery to the San Diego region between 2037 and 2047. Without that water, the San Diego region could face significant supply shortages during future dry years.

The December 2017 action by the Board of Directors was necessary because of mismatched terms in the Transfer Agreement with IID and the related Exchange Agreement with MWD. While the initial term of the Transfer Agreement with IID was 45 years (2003-2047), the Exchange Agreement with MWD had an initial term of 35 years (2003-2037).

Through the end of 2017, the Water Authority has the unilateral discretion to extend the Exchange Agreement by 10 years so that it aligns with the Transfer Agreement, or to end the transfer 10 years early so that it aligns with the Exchange Agreement. Water transferred from IID is highly reliable due to IID’s senior water rights on the Colorado River. The Water Authority’s analysis shows that the price paid by the Water Authority for conserved IID water is competitive with what the Water Authority pays for each acre-foot of MWD untreated water.

Click here to read a memo from the December 2017 Board meeting about the transfer decision.

A Historic Conservation Agreement

The decision by the Water Authority Board has its roots in the historic 2003 Colorado River Quantification Settlement Agreement, which helped reduce California’s use of the river to its basic annual apportionment of 4.4 million acre-feet largely through water conservation-and-transfer agreements.


Since then, increasing volumes of water conserved in the Imperial Valley have been delivered each year to San Diego County under the Transfer Agreement between the Water Authority and the IID. Under its agreement with IID, the Water Authority funds water conservation measures in the Imperial Valley. The Water Authority also pays MWD for transporting the conserved supplies to San Diego County.

The Transfer Agreement will provide 100,000 acre-feet of water to San Diego County in 2017. By 2021, the transfer will ramp up to 200,000 acre-feet of water annually – approximately 30 percent of the Water Authority’s annual supplies – and stay at that level for the remainder of the agreement.

MWD owns the only facility that can deliver the Water Authority’s independent supply of Colorado River water to San Diego County – the 242-mile-long Colorado River Aqueduct. An Exchange Agreement between MWD and the Water Authority governs the deliveries.

The Water Authority retains an option for a 30-year extension of the Transfer Agreement with IID – to 75 years overall – if both agencies agree. In addition, the Water Authority is assessing potential future water conveyance options that don’t depend on MWD – specifically, the cost and feasibility of building its own aqueduct from the Imperial Valley.

While a new conveyance facility would be a significant investment, it could deliver significant benefits, such as transporting conserved water from IID through 2077, if the Transfer Agreement is extended for an additional term. The conveyance facility could also transport water conserved by the lining of the All-American and Coachella canals. The Water Authority receives approximately 80,000 acre-feet a year for 110 years under a contract with the U.S. Department of the Interior.