Fri, Feb. 21

State releases draft plan to help Prescott region stop draining aquifer

State officials released a "working draft" plan Wednesday that they say contains pathways for the Prescott region to stop depleting its groundwater supplies.

The Prescott Active Management Area's Fourth Management Plan is supposed to cover the years 2010-2020 but likely won't be implemented until 2016 or 2017 because of staff shortages, said Jeff Tannler, director of the state's five AMAs for the Arizona Department of Water Resources (ADWR).

"I'm very excited," Tannler told a meeting of the Prescott AMA's Groundwater Users Advisory Council (GUAC) in Prescott Valley Wednesday. "It's been a long time coming, as you know."

This new plan has more of a focus on ways for the AMA to stop depleting its groundwater supplies, he said.

It's supposed to be available online at Comments are due by Sept. 6, and then the agency will create a final draft for public comment. Send an email to, or send him a letter at 3550 N. Central Ave., Phoenix, Ariz. 85012.

The 385-square-mile Prescott AMA includes Prescott, PV and Chino Valley.

The region has been under state-mandated groundwater use restrictions since 1999 because it has been depleting the Little Chino Aquifer. A table in the new draft plan shows annual groundwater depletions during 21 of the last 28 years, with depletions increasing in recent years.

The AMA population uses about 20,000 acre-feet of water annually, and the plan estimates that the population will increase by less than three percent annually. ADWR Planning and Data Management Supervisor Pam Muse said she used the average actual growth between 1985 and 2012.

The state has set a goal of "safe yield," or an end to the depletions, by 2025. It can't enforce that goal but can require some conservation measures, Tannler said.

The plan advocates for regional cooperation and shows three scenarios in which the AMA can reach that safe yield goal, although it also calculates the region still would start depleting its groundwater supplies again as early as 2040.

"We're able to reach safe yield," said PV Town Manager Larry Tarkowski, a GUAC member. "We can do this."

He said a combination of conservation, recharging treated sewage water back into the aquifer, and importation of water from outside the AMA will create success. The region doesn't have much surface water.

But Howard Mechanic, a board member of the local Citizens Water Advocacy Group, was more pessimistic. He noted that the Prescott AMA has gone through three 10-year management plans without progress toward safe yield.

"I'm just going to disagree with Mr. Tarkowski when he says we're headed in the right direction," Mechanic said.

State officials said the AMA cannot reach safe yield without importing water. Prescott and PV have long-standing plans to import water from the neighboring Big Chino Aquifer, but that has caused concerns from others because scientists say the Big Chino provides at least 80 percent of the baseflow for the Upper Verde River.

The draft AMA plan should require Big Chino pipeline mitigation to protect the river, said John Zambrano, another board member on the local Citizens Water Advocacy Group.

"That's something we can definitely consider adding," Tannler replied.

And ADWR should ask local governments to work with the agency on a plan to reach safe yield, Mechanic said.

Local retired civil environmental engineer Doug McMillan advocated for another way to gather new water, through large-scale rainwater harvesting. Only two percent of the AMA's precipitation soaks into the aquifer, often because it evaporates on top of impermeable soils, he said. If the AMA could capture another three percent of that rain it could reach safe yield, he said.

That method is not included in the ADWR draft plan.

"It's definitely something that we want to look at in the future," Tannler said after the meeting in response to a question.

GUAC Member Carl Tenney cited an Upper Verde River Watershed Protection Coalition stalled project idea to test several macro rainwater harvesting techniques that McMillan helped develop.

"I really support the idea of regional cooperation," he said.

The draft plan should consider the effects of climate change, added Jack Hamilton of Dewey.

The plan assumes the region won't see another wet period in the near future, Tannler said.

"We do have climate change in mind with that," he said.

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