Water officials are closing the books on the spring runoff season for the watersheds that feed much of Central Arizona.
Almost twice as much water flowed down from the Salt and Verde highlands as in 2014, which was one of the driest on record. Precipitation was around 75-80 percent of normal.
“But the runoff was much less than that,” said Charlie Ester with the Salt River Project.
SRP supplies water to more than half of the Phoenix metro area. The reason, Ester said, is that there was virtually no snowpack and mostly warm, late spring storms. You can’t think of the watershed as a "tin roof" he explained.
“So it [the watershed] has to get a certain amount of water, basically the holding capacity or the sponge capacity, and once it reaches that point, then the runoff production is pretty abundant,” he said.
SRP’s reservoirs are about 50 percent full at the moment. That is not bad, Esther said, considering nearly two decades of drought in Arizona, similar to the Colorado River Basin.
Without as much runoff, between a quarter and a third of the water utility's supplies are coming from groundwater.
