A long-running dispute over two proposed Central Arizona Project pipelines to Green Valley comes to a head Tuesday.

The Tucson City Council could take a potentially decisive step toward deciding which pipeline will bring CAP water to the thirsty Green Valley-Sahuarita area. It will discuss what criteria to use when making its decision.

The existing pipeline takes CAP water 2.3 miles east from the project's terminal at Pima Mine Road and Interstate 19 to the Pima Mine Road Recharge Project basins near Duval Mine Road and Old Nogales Highway. That project and its pipeline are jointly owned by Tucson and the CAP.

Whoever gets the right to use the line will be able to deliver CAP to Green Valley. That's seen as crucial to reverse a steady decline in the regional aquifer due to continued groundwater pumping for farming, copper mining, subdivisions and golf courses.

Here are the two choices:

Community Water Co. proposes a pipeline for use by Rosemont Copper and, eventually, other CAP users in southern Pima County. It would be paid for by Augusta Resource Corp., Rosemont Copper's parent, and would first take water seven miles south to another set of recharge basins. That water is supposed to replenish groundwater that Rosemont would pump for its open pit mine in the Santa Rita Mountains. Other water users would come later.

Farmers Investment Co., wants CAP water for its Sahuarita pecan groves, which have been sucking down the area's water table for decades. The first phase of the FICO line would run 3.5 miles, but it could eventually run nine miles south.

This pipeline could ultimately bring CAP water to a future, massive development that FICO plans for the pecan grove area - but FICO President Dick Walden says it's at least a decade away.

If FICO and Community Water Co. can tap into the existing line, their officials say that they'll start their projects as soon as possible. If they aren't able to connect to the existing line, they would have to start construction at the CAP terminus at Pima Mine Road. That would slow Community Water's project by five years and could scuttle FICOs plan entirely.

One plan

As Community Water project manager Raul Piña sees it, his project's benefits to the aquifer are obvious.

The pipeline - which the company calls Project Renews - would carry far more CAP water - 28,000 acre feet a year - than the Green Valley company now owns. It now has about 2,800 acre-feet per year.

"We found a way to build the facilities to bring water to the area where, in all honestly, the water needs to be put in the ground," Piña said.

Until the pipeline's construction contracts are signed, backers aren't trying to find other customers to put CAP in the line, said Virgil Davis, the company's board chairman. Piña, however, said "we have other parties that would be very interested." One potential customer, he said, is the Central Arizona Groundwater Replenishment District, a three-county agency that buys and recharges CAP water to support new development.

City Councilman Steve Kozachik doesn't see this pipeline as a net benefit to the aquifer. Neither do Walden and mine opponent Save the Scenic Santa Ritas, who say the Community Water pipeline would only partially offset the impact of new mine groundwater pumping - not reduce existing pumping.

"Rosemont would continue pumping. In addition, all the CAP water that Community Water is getting is dedicated to Rosemont and their groundwater pumping," Kozachik said. "If Rosemont is prepared to cap their wells and use nothing but Colorado River water, and the aquifer is being held harmless, that would be fine. Unfortunately, they have unlimited groundwater rights. At the very best they can say they are mitigating the damage to the aquifer."

Rosemont could legally lease CAP water from Community Water for direct use at the mine, said David Modeer, CAP's general manager. But that would delay the mine project because the feds would have to do an environmental analysis before Rosemont could take CAP water outside the project's service area, he said.

Rosemont Copper said in a statement that the question of its using CAP water directly is not relevant to the pipeline debate.

"The Project Renews pipeline was developed and funded separately to support recharge in Southern Arizona. The project wasn't tied to Rosemont Copper's permitting," said Rod Pace, Rosemont Copper's president and CEO. "For anyone to try to connect these two separate activities is attempting to mislead the public."

Modeer said that he thinks it will take a long time for the recharged CAP water to reach Rosemont Copper's wells and offset their pumping.

Still, "it seems like a good benefit" for Rosemont to have water recharged in Green Valley when, legally, the company can - and has - recharged CAP water in Marana, said University of Arizona hydrology professor Thomas Meixner.

"It's nicer to be on groundwater. You just hook the water on and off when you need it," he said. "You don't have to be on a city water delivery schedule or a CAP delivery schedule."

Second proposal

FICO's pipeline is far less controversial.

Its pipeline would be as large as Community Water's, and could carry far more water than it plans to use now. Said Walden, "The FICO proposal reduces the net draw on the aquifer."

But the project raises questions about how water is used and recharged. The pecan company plans to buy 3,900 acre-feet of CAP water for its groves from a CAP non-Indian agricultural water pool. It will also try to team with other users to put more CAP into the groves.

One prospective buyer - Freeport McMoRan Copper and Gold's Sierrita mine - has asked the City Council to connect FICO to the existing CAP line.

FICO is permitted by the State Department of Water Resources as a Groundwater Savings Facility. Under the state's 1980 Groundwater Management Act and water rules, a municipal or industrial user using CAP there will gain credits letting it pump as much groundwater as it stores, minus some natural losses. It can pump far from where the CAP recharge takes place.

"Water follies. The whole issue is a mess," said Priscilla Robinson, a retired environmentalist and water consultant. "The original groundwater law intended to try to preserve aquifers at some levels … and did not allow any credits for recharge outside of the aquifer being pumped."

Later, that law was amended, allowing recharge far from pumping, she said. "The effect of this change was to abandon the idea of trying to preserve aquifers at some undefined level for some equally undefined future," she said.

Obviously, pumping water closer to where you put it in the ground is better, said Andrew Craddock, manager of recharge programs for the State Department of Water Resources. The state agency is considering ways to give water users incentives to recharge and recover CAP water at the same place.

get all permits first

Tucson could require that a project have all needed permits before the city connects it to a pipeline. That's a key issue to Councilwoman Karin Uhlich.

"How quickly could those pipelines be put in the ground?" she asked. "I don't want to tie up our infrastructure for years for plans that don't come to fruition."

FICO has the major permit it needs - to use the pecan groves as a groundwater savings facility. Community Water Co. still needs to buy an easement on the state land it will use for recharge - a decision on that is due in June. It also needs a state water permit to build a recharge project, a decision that could be up to 300 days off.

Community Water Co.'s Piña says his project can meet this proposed criteria. It will have the permits by the time the pipeline is finished, he said:

"What's going to take us the longest is the construction of the pipeline. As long as we know the rules, we can start construction. It would not delay the project."

On StarNet: Tony Davis will live blog as the council discusses the pipeline. Go to live.azstarnet.com to read the discussion as it happens.

If you go

Tucson City Council study session

discussion of criteria for groundwater recharge in the city and beyond

• When: Tuesday.

• Time: Meeting starts at 1 p.m., but this item is estimated to come up at 1:20 p.m. The discussion is expected to last 45 minutes.

• Location: Mayor and Council Chambers, City Hall, 255 W. Alameda

Contact reporter Tony Davis at tdavis@azstarnet.com or 806-7746.