CAP reliability reservoir on 'back burner' - Tucson Local Media: Pima Pinal

CAP reliability reservoir on 'back burner'

4 utilities now look to recharge of allotments

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Posted: Tuesday, August 31, 2010 11:00 pm

A $60 million-plus reliability reservoir proposed for ground in Marana is largely "off the table," with four Northwest water districts now working to recharge and later consume their Central Arizona Project allotments, officials report.

The four districts — Metropolitan Water District, the towns of Marana and Oro Valley, and the Flowing Wells Irrigation District — are part of the Central Arizona Water Conservation District. They are considering ways to insure the reliability of water through use of CAP allotments.

Mitch Basefsky, CAP communications representative for Pima and Pinal counties, said the choices facing the districts are either a reliability reservoir or a recharge program.

"The reliability reservoir idea is still in the works, with it being discussed by the Bureau of Reclamation and the Northwest side providers," Basefsky said. "They're continuing their talks, but at some point must make a decision while the line item is still in the federal budget."

Warren Tenney, assistant general manager for Metropolitan Water District and a member of the CAP board, said his staff has been directed to look at recharge as the main process for the district. Metro Water is in the process of finalizing acquisition from CAP of the Avra Valley Recharge Project.

"We began talks three years ago about where water was being stored and the Avra Valley site wasn't being used much for recharge," Tenney said. "We had concerns about where we could recharge if groundwater savings facilities didn't continue in the future."

Tenney said the cost of purchasing the site at $1.7 million would be funded using effluent credits that would be transferred to the Central Arizona Ground Water Replenishment District. He expects the transfer to be complete by the end of the year.

Metro Water's CAP allocation is 13,460 acre-feet per year. An acre-foot is 325,851 gallons.

Recharge of CAP water is a distinct shift from earlier consideration of a reliability reservoir near I-10 and Tangerine Road that would serve the four Northwest water providers.

"At one time, we planned for a larger reservoir where the water could then be treated and delivered, but that idea got put on the back burner," Tenney noted. "In the last two years the Bureau of Reclamation crunched the numbers and looked at the design of the reliability reservoir, projecting the cost at around $75 million. That raised a concern for us because originally we had talked around $30 million."

After fine-tuning the numbers, the Bureau of Reclamation came up with a figure of between $60 million and $70 million, Tenney said. In addition, the town of Marana expressed concerns about the reservoir's design because of 30-foot-high berms that would face the canal, so that instead of seeing water, people would be faced with a huge, earthen wall, and there would not be recreational opportunities.

Dorothy O'Brien, director of Marana's water utility, said after the original concept of the reservoir was taken off the table, recharge looks like the way to proceed.

"While our CAP allocation is not nearly as large as that of Metropolitan Water District or Oro Valley, we have been recharging all of our CAP into the Lower Santa Cruz Recharge Project site," O'Brien said. The recharge site is on the west side of I-10 and west of the river, near the Marana Regional Airport.

O'Brien noted Marana also has worked over the past six months with the state Department of Water Resources to get all Marana groundwater wells converted to recovery wells.

"We have 23 wells and are getting them all permitted as recovery wells," she said, "and expect to have the permits finalized in the next three months, certainly well before the end of the year."

Marana will continue to recharge its CAP allocation of 1,528 acre-feet per year at the Lower Santa Cruz Recharge Project site, O'Brien said.

Philip Saletta, director of the Oro Valley water utility, said the town wants to retain all options in terms of delivery of CAP water.

"We're looking at cost comparisons to determine which is most viable and economically feasible," Saletta said.

While Oro Valley considered the idea of a reservoir fed by the CAP canal and then distributing treated water to the town, he noted Oro Valley is now considering recharging CAP water at existing recharge locations, then constructing recovery wells and planning for distribution.

"For Oro Valley, the Lower Santa Cruz Recharge Project is the best location," Saletta said. "We already have the permits to store water there, but don't have permits for the recovery wells yet."

Saletta said Oro Valley would have to drill several wells in the vicinity of the location, get them permitted as recovery wells, then build a pipeline from the site to distribute water in Oro Valley. The town's CAP allocation is 10,305 acre-feet annually.

"Originally we looked at delivery of that water in 2014 or 2015, but the slowdown in growth has affected that timeline," he said. Now we're looking at around 2016 for delivery."

David Crockett, superintendent of the Flowing Wells Irrigation District, said his district will follow the lead of the other three.

"The reservoir is off the table at this point, pretty much due to funding," Crockett said. "Some of the other providers have chosen to go with recharge-recovery, and because we're not large enough to go it alone, we'll have to go along with the group."

The Flowing Wells CAP allocation is 2,873 acre-feet a year.

"We'll do the recharge at the Lower Santa Cruz Recharge Project and recover from six of our eight wells, which are all permitted as recovery wells," Crockett said. "We've been working together for 10 years on this and are trying to make good, informed decisions for our customers."

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