The return of extra-cool surface temperatures in the Pacific Ocean could produce another dry winter for Arizona — renewing the grip of a decade-long drought on the Southwest.
The cool La Niña conditions in the Pacific typically shift winter storm tracks north of Arizona say forecasters. That means despite a brief, near-normal return to normal last year, the mega-drought that set its teeth in the state back in 1999 isn’t ready to let us go.
The rare back-to-back La Niñas mean another tough year for ranchers, farmers and reservoir managers, with the chance of another terrifying wildfire season next spring.
Although some areas in the Rocky Mountains and Arizona had above-normal snowfall early in the winter, the spring turned bone dry and the monsoons proved disappointing.
So far, Payson has received 12 inches of rain since January, compared to a long-term annual 12-month average of about 26 inches.
The reservoirs on the Salt and Verde Rivers were full to overflowing with the first flush of snowmelt this spring, but have now declined to 74 percent of their capacity on the Salt River and 30 percent of capacity on the Verde River, according to Salt River Project reports. On Monday, the flow of the Salt River stood at 145 cubic feet per second, less than half of normal. The flow of the Verde River stood at 125 cubic feet per second, about 73 percent of normal.
Meanwhile, Tonto Creek now dries up completely before reaching Roosevelt Lake, although normally at this time it would still be carrying about 9 cubic feet per second.
Fortunately, the Salt River Project continues to augment the flow of the East Verde with the release of about 25 cubic feet per second from the Blue Ridge Reservoir at Washington Park. That water helps keep well levels up in Rim Country and eventually ends up in Horseshoe Reservoir near Phoenix.
The return of the drought underscores the importance of the still behind-schedule Blue Ridge pipeline project, which will double Payson’s long-term, assured water supply. Once the Blue Ridge water arrives in 2014, Payson’s groundwater wells should recover from decades of over pumping and the town will become one of the few towns in Arizona with enough water to supply all its future growth plans — even if Arizona State University builds a 6,000-student campus here.
The U.S. Weather Service has listed Gila County as suffering from moderate to severe drought. That’s rough, but not nearly as bad as a big chunk of the Navajo Reservation to the north and most of southeast Arizona, where the drought qualifies as “extreme.”
The reservoir on the San Carlos Reservation near Safford has dwindled to about 4,000 acre-feet, compared to a capacity of 1.2 million acre-feet. It has shrunk already to a level that could cause massive fish kills if the winter rains fail.
Fortunately, Roosevelt Lake remains about 70 percent full, a boon for Phoenix since the reservoir supplies a major share of the Valley’s drinking water. Several years ago, the drought had driven Roosevelt down to about 15 percent of its capacity.
Forecasters say that most of the state will face an unusually warm, dry winter, after an exceptionally dry spring and a spotty monsoon. Those conditions contributed to the largest wildfire in state history up in the White Mountains and record-breaking temperatures and massive dust storms in Phoenix throughout August.
The monsoons that normally deliver about half of the Valley’s annual rainfall this year produced about two-tenths of an inch in August.
The abnormal conditions have also caused massive wildfires in Texas, record-breaking drought in Georgia and catastrophic flooding in other areas of the nation.
Climate experts continue to struggle when it comes to predicting the impact of global events like La Niña and its twin El Niño, caused by the warming of surface waters in the Pacific, which generally increase rainfall in the Southwest.