March weather dries up chance to end drought
by Shaun McKinnon – Apr. 2, 2009 12:00 AM
The Arizona Republic
Better hold on to the eulogy for Arizona’s long dry spell.
A series of winter storms built up snowdrifts – and hopes – in December and January, but an abrupt onset of drier conditions diminished chances of ending the drought, which has persisted for more than a dozen years.
March ended as one of the driest on record across the river basins that supply water for Valley cities, and those rivers will likely produce only about two-thirds their typical flow into storage reservoirs.
It’s a sharp turnabout after those early winter storms piled snow high in the mountains and somewhat surprising after watching water spill out of Roosevelt Lake.
“I think when it’s over, they’re going to say La Niña really took hold,” said Charlie Ester, water-resources manager for Salt River Project, which stores and distributes water from the Salt and Verde rivers.
La Niña, a lowering of water temperatures in the Pacific Ocean, often produces dry winters in Arizona and the Southwest. Climate experts spotted it late last year and factored it into their forecasts.
Its influence seemed muted at first, as storms in December boosted mountain snowpack. But the storms slowed by February and produced next to nothing by March. Just 0.12 inches of precipitation fell on the Salt and Verde watersheds in March, Ester said.
The average for the month is almost 2.5 inches.
SRP now estimates the season-long runoff on both major river systems to top off at about 67 percent of the long-term median.
Roosevelt Lake filled in part because its levels were high to begin with. Then rain-fed runoff raised levels quickly before water demand could keep up. SRP was forced to release water for more than a month to keep the reservoir below federal flood-control limits.
Horseshoe and Bartlett lakes on the Verde River never filled and sit at 79 percent of capacity.
SRP will draw its water supplies from the Verde this spring in an attempt to lower water levels at Horseshoe Lake, which operates under a special wildlife-habitat plan. The lower levels are required to prevent non-native fish from reproducing.
Conditions turned similarly dry in Phoenix, where Sky Harbor International Airport hasn’t recorded measurable rain since Feb. 17. The airport has received 1.47 inches of rain since Jan. 1, about 1.2 inches below the 30-year average for the first three months of the year.