Coalition to discuss how to stop depleting aquifer
PRESCOTT - The Upper Verde River Watershed Protection Coalition will discuss a new "safe yield" report Wednesday.
The meeting starts at 2 p.m. at Prescott City Hall, 201 S. Cortez St. The report is available on the coalition's website at www.uvrwpc.org.
"Safe yield" is a governmental term that means a balance between the amount of groundwater going into and out of an aquifer. The Arizona Department of Water Resources concluded in 1999 that the Prescott Active Management Area (AMA) is out of safe yield. The AMA has continued to deplete its groundwater supply in subsequent years.
The AMA encompasses 485 square miles and includes Prescott, Prescott Valley, Chino Valley and the Yavapai-Prescott Indian Reservation, and all of those municipalities are members of the coalition along with Yavapai County.
The coalition created a safe yield workgroup to come up with recommendations about how to reach safe yield. The subcommittee members represent a variety of stakeholders, from environmental interests to private water companies to residential well owners.
The subcommittee's new 25-page report concluded the Upper Verde Coalition should morph into a replenishment district to meet its goals of reaching safe yield while preserving the baseflow of the Upper Verde River.
"The existing coalition structure will not be able to provide adequate funding or decision making unity in order to reach safe yield," the report's conclusion states.
A replenishment district "will be able to collect revenues necessary to implement a safe yield plan with its associated conservation, harvesting, recharge, and importation projects without stripping the relevant authorities of the current cities and towns," according to the report.
A replenishment district may or may not require legislative approval, depending on its structure, the report states.
The report analyzes four alternatives to help the coalition reach its safe-yield goal: keep the current structure, enhance the current structure, create a replenishment district, and create a water authority.
An enhanced coalition would require binding membership, but it still would have to allow individual member groups to approve its actions, and it wouldn't have the authority to issue bonds without legislative authority, the report states.
A stronger regional water authority would have its own regulatory authority, the report explains. It also would have eminent domain powers that a replenishment district would not have.
The report estimates that the Prescott AMA is depleting its groundwater supplies by about 11,000 acre-feet annually.
Future water demands could increase the groundwater overdraft by as much as 4,090 acre-feet per year, the report estimates.
It based its estimate on the fact that the AMA has 10,000 platted, vacant subdivision lots with rights to access groundwater. And a study for the Yavapai County Water Advisory Committee by H3J Consulting calculated that the number of residential wells in the AMA will increase by 3,100 by 2020.
The AMA currently has about 10,000 residential wells, all of which can pump 35 gallons per minute of groundwater.
The report also notes that 90 percent of the 105 Prescott AMA wells that the Arizona Department of Water Resources measured between 2003 and 2004 had a mean annual water level decline of 2.7 feet. A longer-term measurement of 55 sample wells from 1994 to 2004 showed a mean annual water level decline of about 1.4 feet.
Without action to return to a more balanced aquifer use, the AMA faces the possibility of wells going dry, plummeting land values and tax revenues, damage to natural resources, geologic changes that could inhibit the aquifer's ability to hold groundwater, land subsidence and reduced attraction for future economic growth, the report concludes.
The region will need a combination of water conservation, groundwater recharge projects, and water importation from other areas to reach safe yield, the report concludes.
It estimates that conservation methods would cost about $3,000 per acre-foot of water gained, compared to $25,000 per acre-foot of water gained through increased groundwater recharge or water importation.