With a Thursday decision, the Central Arizona Project board of directors has given Southern Arizona water subcontractors – including the towns of Oro Valley and Marana, along with Metro Water and the Flowing Wells Irrigation District – greater certainty for year-round access to supplies.
CAP has agreed to reserve storage capacity for the suppliers at its two county recharge facilities, providing water that may be undeliverable during annual system maintenance.
CAP plans to reserve 2,278 acre-feet (750 million gallons) of storage capacity at the Lower Santa Cruz Recharge Project in Marana to ensure reliability for the four entities. For the City of Tucson and other water providers, CAP is setting aside 6,000 acre-feet (nearly 2 billion gallons) of capacity at the Pima Mine Road Recharge Project south of Tucson.
“We are really pleased to have achieved a consensus solution to ensuring water reliability for the Pima County CAP users,” said CAP board member Carol Zimmerman of Tucson. “This is a long-awaited and truly significant step toward regional sustainability.”
The plan follows decades of studies by the Bureau of Reclamation, and extensive discussion among local water subcontractors, a CAP release said.
“Essentially, it means they can now plan on having the capacity available to them to accept their entire allocations each year, and to ensure they’re going to go in projects in Pima County,” said CAP spokesman Mitch Basefsky. “It gives them a certainty that has been missing in the past.”
At issue — annual interruptions for maintenance, which diminish or cut off CAP water supplies to the region.
Pumping plants along the southern portion of the CAP have a single discharge line, CAP said. That means deliveries must be interrupted for annual scheduled maintenance.
Typically, such work is done in the fall, Basefsky said. Flows are turned off, or are “much diminished,” during maintenance work, leaving end users with less water for recharge or consumption.
“Primarily, it puts a crimp in their ability to use their full allocations, particularly Tucson,” Basefsky said.
Those estimated 30-day volumes of CAP supply that can be interrupted add up to 11,665 acre feet for the City of Tucson, 1,089 acre feet for Metro Water, 834 acre feet for the Town of Oro Valley, 246 acre feet for the Spanish Trail Water Company, 231 acre feet for the Flowing Wells Irrigation District, 150 acre feet for the Vail Water Company and 124 acre feet for the Town of Marana. Those volumes represent about 1/12th of each subcontractor’s annual CAP entitlement.
“This plan allows them to use existing recharge facilities to meet that reliability need,” Basefsky said. “This capacity is reserved for the people who have allocations. Essentially, it gives the municipalities the right of first refusal.”
In the Northwest, “none of them are using the water in their system” currently, Basefsky said. Oro Valley and Metro Water have their allocations recharged on their behalf. Tucson Water does use its CAP supply directly for drinking water. There are direct agricultural and mining users, too, Basefsky said.
CAP is planning to spend $6 million in reserve funds to make this work. That sum represents “working capital,” or funding “set aside for unexpected or unscheduled expenses,” Basefsky said.
“We are setting aside these funds to pay for future reliability costs,” he continued. “Those costs could potentially be related to recharge project improvements, groundwater credits, or some other mechanisms that provide the amount of water specified for each of the customers. The specifics have yet to be worked out by all of the parties.”
Governing boards for each Southern Arizona water provider must ratify the agreement.
CAP operates the 336-mile-long CAP system, bringing about 1.6 million acre-feet of renewable Colorado River water to cities, businesses, agriculture and Indian communities in Pima, Pinal and Maricopa counties. An acre-foot of water is about 326,000 gallons.