Big Chino Water Ranch: Science-gathering phase continues
Current analysis of the aquifer plans will not be done before 2020
Prescott has been eyeing the Paulden-area Big Chino Sub-Basin as a possible source of imported water since the 1970s; four decades later, officials are still in search of answers.
Leslie Graser, the City of Prescott’s Water Resource Manager, outlined the basics of the Big Chino issue during an update on the status of the city’s plan to pump thousands of acre-feet of water per year from the aquifer and pipe it to the Prescott/Prescott Valley area.
“Prescott was talking about the Big Chino back in 1977,” Graser told the several-dozen people who turned out at the Prescott Public Library Sept. 19, for the latest in the city’s “WaterSmart: Drop by Drop” series of presentations.
Graser’s presentation materials included a “Comprehensive Water Study of the City of Prescott and Environs” from 1977, which began with, “The City of Prescott has investigated the possibilities of developing water resources from Big Chino Valley.”
Now 41 years later, the city is still studying the issues, and has at least 2½ years to go before the completion of the most recent analysis on the Big Chino plans.
Graser stressed several times that interested parties were still in the information-gathering phase on the Big Chino importation issue. “Right now, we’re doing the science,” she said.
The September presentation, which was the ninth in the monthly Drop by Drop series, focused on the Big Chino Water Ranch — the parcel of ranchland northwest of Paulden that Prescott and Prescott Valley bought in 2004 as a possible source of imported water.
In the face of ongoing litigation in the early 2010s, the city entered an agreement with Prescott Valley and the Salt River Project for an eight-year modeling and monitoring study to determine if the planned Big Chino pumping would affect the flow of the Upper Verde River.
Graser, who stressed that the Drop by Drop talk would focus on “the basics” of the issue rather than the politics, started with a timeline of water issues, including the 1999 declaration that the Prescott Active Management Area was no longer in “safe yield” — the condition of balance between the amount of water being pumped from the ground, and the amount being recharged back in.
The safe-yield issue pertains to the Little Chino Basin, from which Prescott gets the bulk of its water supply. Importation from the separate Big Chino aquifer was seen as a way to augment the supply to help bring the area back into safe yield.
While Prescott has the right to pump 8,068 acre-feet of water from the Big Chino annually, the process was put on hold when the city and its partner Prescott Valley entered a comprehensive agreement with the Salt River Project in 2012 to undertake a massive monitoring and modeling process to get more data on the impacts of the pumping. The study got underway in 2013.
Graser’s presentation stated: “Withdrawal of the recognized quantity is being scientifically evaluated by the city, the Town of Prescott Valley, and the Salt River Project (SRP) via a cooperative study.”
Under the agreement, SPR is responsible for one-third of the cost of the analysis, while Prescott and Prescott Valley are responsible for two-thirds, with Prescott taking on 54 percent of the remaining amount, and Prescott Valley taking on 46 percent.
So far, the analysis has cost the three parties upwards of $2 million. Graser reported that the cost through the end of the previous fiscal year (ending June 30, 2017) totaled about $1.2 million. Although the exact totals for the next fiscal year are still being determined, Graser said at least $1.1 million has since been spent on the drilling of seven monitoring wells.
Based on those costs and the agreed-upon breakdown, Prescott’s share of costs to date total more than $800,000.
“We are basically in year 5,” Graser said of the ongoing study. Along the way, she said, the results are being analyzed, with the help of consultants, and a technical committee made up of representatives from Prescott, Prescott Valley and SRP meet monthly to discuss the ongoing progress.
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