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Sun, Oct. 20

GP 2020 'needs work on effluent,' changes purpose of open space

(Editor's Note: This is the fourth in a series of General Plan 2020 articles intended to encourage residents to read the draft plan for themselves and submit comments to the Town. Residents can see the draft plan at the Town library, view it on-line at, or obtain a copy on CD-ROM from the Community Development Department in the civic center.)


Chapter 6 of General Plan 2020, the Environmental Planning and Water Resources Element, describes Prescott Valley's water resources and air quality, and how the Town will continue growing with a minimal impact on those resources.

The chapter reviews Arizona's Groundwater Management Act of 1980 and describes the Prescott Active Management Area (AMA) as aquifers isolated from the rest of the state. The general plan acknowledges that the population is already withdrawing more water from the aquifers than is being replenished ("overdraft"), and that declining water levels in wells is probably not reversible.

"Additional groundwater-based development in the AMA can only, over the long term, intensify the current water level declines," it reads.

That said, GP 2020 indicates pumpage for Prescott Valley will be at 13.2 million gallons per day (MGD) by Spring 2002, with 1.6 MGD of effluent - treated wastewater - discharged into the Agua Fria riverbed.

Here in Chapter 6 the Tribune found a statement needing some clarification, where GP 2020 claims the effluent "is recharged into the aquifer within two miles of traveling downstream. These groundwater credits will help bring the Prescott AMA back into a 'safe-yield' condition" (safe-yield is the condition of replacing as much water as is removed from the aquifer).

While GP 2020 appears to claim the effluent recharges the aquifer from which it was drawn, in the Arizona Department of Water Resources' model for the AMA the effluent actually flows out of the AMA and is lost to re-use, whether or not it recharges the aquifer further downstream.

The fact is, according to Prescott AMA Director Jim Holt, the Town has only applied to ADWR for a permit to operate a "recharge facility." The Town hired a hydrologist to present his own model of the AMA that shows the effluent discharge remains in the AMA, and the Town submitted that hydrologist's data and conclusion with its application.

It's an important point because ADWR can issue "recharge credits," allowing the Town to withdraw additional groundwater equal to the amount of effluent that it recharges to the aquifer. More water equates to more development.

"ADWR said if we want recharge credits for that effluent discharge, we have to prove it doesn't leave the AMA," said PV Public Works Director Larry Tarkowski. "We took their advice rather than fight about it because we are partners with the department, not adversaries. We got a consultant that has gathered data to support our case, that we should have recharge credits."

As of today, however, the ADWR model stands. "We are not issuing Prescott Valley any credits at this point," Holt said.

In an apparent contradiction to the plan's claim for recharge credits for that 1.6 MGD, GP 2020 says the Town already has development agreements with the Stoneridge and Granville developments to provide that 1.6 MGD of effluent during the summer to water their golf courses (ADWR does not consider that use as being recharge). And the plan says the Town will also continue to tap off enough of that effluent discharge to keep full two recharge basins on Lakeshore Drive.

Tarkowski said the paragraph is explaining the Town has agreed to provide effluent to Stoneridge and Granville golf courses, with peak summer usage projected at 1.6 million gallons per day, with far lesser amounts needed during the rest of the year. He agreed that, for the sake of clarity, the paragraph should read that golf course amount as simply 900 acre feet of effluent each year from a total annual discharge of 2,000 acre feet, and should use the acre-foot unit of measurement throughout that section of the chapter.

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