Despite years of growing concern about drought, some good water news has emerged: The Tucson area has balanced its water pumping with recharge more than a decade ahead of schedule.
Achievement of what’s known as safe yield means that the Tucson area meets a 33-year-old state requirement.
Local water authorities say this is a huge accomplishment, since the state-set deadline for safe yield isn’t until 2025.
It caps more than three decades of concerted effort by government officials, individuals and businesses to conserve water and switch from groundwater to renewable supplies.
But state and local officials acknowledge that the region’s water problems are far from solved and that future shortfalls in Colorado River supplies could threaten safe yield.
The safe yield requirement was set by the 1980 Groundwater Management Act, a pioneering state law aimed at ending chronic groundwater overpumping dating to World War II.
The law made the Tucson area and four other urban regions active management areas, meaning their groundwater supplies are regulated by the state.
In the Tucson area, groundwater recharge exceeded pumping every year from 2005 to 2010, a recent Arizona Department of Water Resources report shows. Those are the most recent statistics available.
“Difficult days and decisions are surely still ahead, but let’s take a moment to celebrate this simple fact and acknowledge the efforts that made it possible,” wrote Val Little, a member of a state water advisory council, and David Crockett, superintendent of the Flowing Wells Irrigation District, in an essay announcing the safe yield achievement.
Little and Tucson Water official Wally Wilson noted, however, that the water table is still falling beneath Green Valley, the pecan groves in Sahuarita and in Oro Valley, among other areas.
Little and Crockett’s essay also took note of recent bad tidings for the Colorado River, due to prolonged drought, although Tucson Water hopes to store enough Central Arizona Project water to serve as a buffer against river shortages well into the 2030s.
“Safe yield with some holes in it is a good description,” said Little, who also directs the Water Conservation Alliance of Southern Arizona.
Anyway you slice it, however, the region has come a long way.
Back in the early 1980s, the Tucson area pumped two to three times as much groundwater as was being replenished by rainfall or, artificially, by treated sewage effluent.
The city has for the past 13 years ramped up its use of CAP water, replacing pumped groundwater. It has been recharging and storing CAP water it doesn’t use.
Water users such as Oro Valley, Metro Water and others have recharged CAP water into basins in the Avra Valley. Oro Valley has started directly using some CAP water by having Tucson Water send it through its pipes into the northwest suburb. More such deals between the city and suburbs are in the works.
Water conservation has accelerated, with many municipalities reporting decreased per-person and/or total water use in recent years, even with population growth. Low-water-use landscaping, gray water, rainwater harvesting and numerous local water ordinances have cut water use.
More treated sewage effluent has been used in parks and on golf courses, replacing groundwater. Farms are also using treated effluent.
“Best of all, the people of Tucson understand the importance of water in our arid desert and recognized that the cheapest water is the water we don’t use,” Little and Crockett wrote.
But while this is all terrific, “let’s not get carried away,” remarked University of Arizona law professor Robert Glennon, who has written two books on water.
“Yes, we’ve reached equilibrium in our water pumping and recharge. But that is in part due to a huge downturn in our local economy and the flatlining of our housing sector, which have reduced consumption.
“We also have a temporary surplus of CAP water, and no one thinks this is going to last for the long term,” Glennon said. “And while the water table is at equilibrium, it’s down so far that we’ve done tremendous damage to our riparian areas.”
David Godlewski, head of the Southern Arizona Home Builders Association, saw the situation more optimistically, calling the safe yield achievement very positive news showing the success of Tucson’s comprehensive water policies and conservation efforts.
He said he needs to better understand the region’s water picture before saying exactly how the safe yield status affects future growth and homebuilding.
But he noted that new homes are more and more efficient in their water use all the time, while “things can be done with existing homes to help continue to conserve water.”
State Water Department officials said that while their report showed recharge exceeding pumping throughout the 2005-10 period, there were only two years, 2006 and 2010, when the recharge exceeded pumping by a significant amount.
From a physical standpoint, we were at safe yield all six years. But from a strictly regulatory standpoint, Tucson met the safe yield goal only in 2006 and 2010, the state water agency said.
That’s because some of the recharged water in that period represents, on a legal basis, artificially recharged, long-term water storage credits, that are essentially licenses for future pumping.
Such credits aren’t included in the totaling of water pluses and minuses that determine if a region is legally in safe yield, said Michelle Moreno, a state water agency spokeswoman.
“We need to keep on top of things and stay vigilant,” said Doug Dunham, a special assistant to the state water agency’s director. “We’re on the edge. if there’s lots of increased demand, or lots of decrease in renewable supplies, we will be back in an overdraft position.”
Recent years of recharge exceeding pumping doesn’t put the region permanently at safe yield, Moreno added, because the legal requirement is to reach safe yield by 2025 and stay there.
On that point, Little and Crockett agreed, “just to reach safe yield at a specific time isn’t an adequate goal,” they wrote. “Our more difficult, but more important goal, is to achieve a permanent water balance.”