This article has been updated to clarify the letter's intent.
The Center for Biological Diversity called on the Arizona Department of Water Resources (ADWR) to curtail the use of groundwater in the Upper San Pedro River Basin.
Research indicates the aquifer in the Sierra Vista sub-watershed has suffered significant depletion.
The reductions the group is calling for would apply to groundwater wells and certificates in the area, assuring a 100-year water supply approved by the department.
Robin Silver with the Center for Biological Diversity has raised concerns about how over water users in the Sierra Vista area have been treated unfairly by the ADWR.
In a letter addressed to the ADWR, the center demands an apology "to the more than 22,200 people in the Sierra Vista area, dependent on groundwater provided by either one of the 2,439 ADWR approved wells or one of the 66 local water suppliers with ADWR 100-year Water Adequacy Certificates approved after November 18, 1988, who now face inevitable water use reductions."
Silver told AZPM, “everybody that was considering buying a home in the Sierra Vista area should have been clearly advised that this day would come when they would have to have their water use reduced to a degree that would have allowed the San Pedro River to survive.”
Cochise County environmental activist Tricia Gerrodette told AZPM she is working on the issue with Silver. She said currently, Pueblo Del Sol Water has its own designation of water adequacy.
Silver pointed out that the San Pedro River does not belong to the City of Sierra Vista or the Cochise County Board of Supervisors.
In 1988, the San Pedro National Riparian Conservation Area preserved 57,000 acres of public lands and federal water rights under the jurisdiction of the Bureau of Land Management.
According to Silver, the overdrafting of the aquifer in the Sierra Vista sub-watershed has been happening since the 1970s.
“It’s water that’s stolen from the San Pedro River and from federal reserve water rights,” Silver said. “The amount that's stolen is dependent on the location of your source well.”
The extent to which a well needs to be reduced depends on its geographic location. Silver said that in the Sierra Vista area, most wells are subject to reductions between 10% and 40%.
Water rights within the area remained unclear for decades until a Maricopa County judge quantified them in August. The judge mandated that groundwater levels be maintained at nine specific well-sites, but the center alleges that two wells have fallen below their required elevation, constituting a violation of the ruling.