Groundwater users in southern Arizona will soon be seeing water use restrictions.
The Center for Biological Diversity penned a letter to the Arizona Department of Water Resources (ADWR), calling for a reduction in groundwater use in the Upper San Pedro River Basin to accommodate water rights for the San Pedro National Riparian Conservation Area.
“For decades the Arizona Department of Water Resources has approved the use of more groundwater than it knew would be available,” said Robin Silver of the Center for Biological Diversity in a statement. “By prioritizing the interests of developers, the agency shortchanged the San Pedro River and burdened residents with water use reductions that will inevitably come to pass.”
The group wrote in its letter that the water department “can no longer hide behind its ‘federal reserved water rights are not quantified’ excuse,” as the Superior Court of Arizona released an order quantifying water rights for the conservation area in August. Under the order, groundwater levels must be maintained at nine monitoring wells within the conservation area.
The Center calls for the ADWR to apologize to the more than 22,200 residents of the Sierra Vista area (south of Tuscon) who are dependent on groundwater, as they will now face water use reductions. The group said the department has been deceitful for decades by “rubber-stamping unsustainable local water use and by refusing to clearly advise local well owners and homebuyers that the day would inevitably come when their groundwater use would need to be reduced.”
The environmental group cited a 2011 study prepared by a consulting group for Friends of the San Pedro River and the Walton Family Foundation that found the river will disappear over the next century if water use is not adjusted.
“ADWR has been knowingly contributing to and has facilitated the development of this crisis for decades,” the Center concluded in its letter. “ADWR can no longer ignore addressing and working to resolve this crisis that ADWR itself has helped create.”
Conflicts in the San Pedro Riparian National Conservation Area have been numerous over the past few years, with environmentalists accusing the Bureau of Land Management (BLM) of favoring cattle ranchers for livestock grazing in the conservation area. Most recently in April, BLM authorized livestock grazing on four allotments within the conservation area.
Background
The San Pedro Riparian National Conservation Area is a two-mile wide riparian corridor that covers 57,000 acres along the San Pedro River in southern Arizona. The conservation area was created in November 1988 to protect the riparian area and the aquatics and wildlife the area contained.
The Superior Court of Arizona ruled on Aug. 25 to quantify the water rights in the conservation area to protect fish species. “The standard governing the quantification of a federal reserved water right calls for neither the optimum amount of water to provide fish habitat nor optimum streamflow,” the court wrote. “The specific quantity of water is, instead, a function of the amount sufficient for the survival of the desert sucker.”
The court ordered the conservation area to be entitled to federal water rights defined as monthly flows for each month. Monthly flows are determined as the median rate of the mean daily flow for each month from 1981-2015. The area is also entitled to flood flows, calculated as the difference between the sum of the monthly flows and the mean annual flows.
After the court’s ruling, groundwater pumping by Sierra Vista will need to be reduced, with the amount dependent on the distance of water wells from the San Pedro River. — Anna Miller, WLJ managing editor
