The El Nino weather pattern has been sporadic this winter in Arizona but early season storms should help produce more snowmelt runoff than the past five years, according to Salt River Project projections.
That’s good news for the state’s agriculture industry and others who depend on winter storms for adequate water resources.
SRP is forecasting this year’s runoff from January to May at about 585,000 acre feet of water. That is 9.5 percent above the 30-year median runoff of 534,336 acre feet.
An acre foot of water is 326,000 gallons or roughly enough to serve an Arizona family of five for a year.
The state has experienced five straight runoff seasons of below-median flow into the reservoirs on the Salt and Verde rivers, according to SRP.
“We’re keeping our fingers crossed that the pattern of strong El Ninos holds up, and that this one still may have some work to do in March,” said Charlie Ester, SRP Water Resource Operations manager. “If that’s the case this year, we’ll take it.”
He said a median January-to-May runoff season would help refill the six SRP reservoirs, which rose to 57 percent in early March compared to 53 percent one year ago, but would likely not completely fill the reservoirs.
The last wet winter came in 2010 when 1.43 million acre feet of precipitation filled the Salt and Verde reservoirs and prompted releases in the normally dry Salt River through the Valley.
Two years ago was the eighth driest year for runoff in the 118 years that SRP has been keeping records. Runoff was 148,000 acre feet in 2014.
An SRP snow-measuring team recently visited locations in the White Mountains to get an early indication of where this year’s runoff numbers are headed.
The good news is that the El Nino weather pattern delivered an early amount of snow over SRP’s 13,000-square-foot watershed. And El Nino may not be finished for the season.
The National Weather Service outlook for March favors “above-normal” precipitation (about a 43 percent chance) over “below normal” (about a 24 percent chance).
SRP is the largest raw water supplier in the Phoenix metropolitan area, delivering about 800,000 acre-feet annually to agricultural, urban and municipal water users.
