Each year, about 6 million acre-feet (AF) of Colorado River water is regulated at Imperial Diversion Dam, just north of Yuma, Arizona, for irrigation and other uses in California, Arizona and Mexico. That water must be released from storage in Lake Mead, nearly 300 miles to the north. It takes about five days for water released from Lake Mead to reach Imperial Dam.
By the time the water arrives at Imperial Dam, the water users that scheduled the water delivery may be unable to take it due to factors that limit those water users’ ability to utilize the water (such as the occurrence of precipitation during those 5 days for agricultural water users). In order to address this requested water that otherwise would be lost to the system, the United States Bureau of Reclamation (USBR) coordinated the construction of Brock Reservoir.
Brock Reservoir is a man-made reservoir, composed of two basins, with a total combined capacity of 7,945 AF. This project was approved and constructed during the period of 2008-2010, with a total cost of $172 million, and was partially financed by CAP, Southern Nevada Water Authority (SNWA), and Metropolitan Water District (MWD) of Southern California, each with an equal contribution of $28.6 million. According to USBR, it is estimated that the project could save 70,000 AF per year. As part of their contribution, SNWA can use 400,000 AF of Intentionally Created Surplus (ICS) water credits over 20 years, while CAP and MWD can each use 100,000 AF of ICS water credits starting in 2016.
MWD Regional Recycled Water Program
The Arizona Department of Water Resources (ADWR) and Central Arizona Water Conservation District have signed a letter of intent to pursue collaboration with the Metropolitan Water District (MWD) of Southern California’s Regional Recycled Water Project (RRWP). This project would purify and reuse wastewater and potentially offset the use of imported supplies such as Colorado River water.
The collaboration is an extension of cooperative efforts, including with the Southern Nevada Water Authority to explore and develop new projects and infrastructure to potentially augment the Colorado River. The RRWP is a unique opportunity to potentially improve the reliability of Colorado River water supplies to benefit Arizona, California and Nevada water users and create new flexibility and resiliency in the Colorado River system.
Yuma Desalting Plant
As a part of Minute 242 and its intention to define a “permanent and definitive solution” to the international salinity problem of water deliveries to Mexico, the USBR was authorized to construct and operate the Yuma Desalting Plant (YDP) to treat Wellton Mohawk Irrigation and Drainage District’s (WMIDD) drainage water, and deliver the treated water as a part of the U.S. treaty obligations for water deliveries to Mexico.
Due to different factors, YDP has remained largely inactive since construction was completed in 1992. Current drought conditions and increased water uses exacerbate the vulnerability of Lower Basin users to Colorado River’s water shortages. This has motivated water users to evaluate the operation of YDP (2010 Pilot Operation Run and Evaluation of Technological Advancements and Alternative Feed Water Supplies for Operation of Yuma Desalting Plant- CRADA Report) as well as consider alternatives to operating the plant (Yuma Desalting Plant (YDP) Long Term Operational Alternatives).