2010 runoff season fills SRP reservoirs
10th wettest winter on Salt and Verde watershed; several records fall
The probability of a drier-than-normal monsoon season and the forecast of a potentially dry La Nina winter in 2011 aren't enough to diminish the excitement of SRP water managers, who enter the summer months pleased that the reservoirs on the Salt and Verde rivers are nearly full and operating exactly as they're designed.
Charlie Ester, manager of Water Resource Operations, said SRP's six reservoirs on the Salt and Verde enter summer in great shape following one of the most beneficial runoff seasons on record. SRP's reservoirs are currently at 96 percent of capacity with about 2,222,000 acre feet of water -- thanks to a final January-through-May runoff total of 1,430,841 acre-feet, one of the 20th best in SRP's 107-year history and 209 percent above the median runoff of 683,635 acre-feet for the two river systems.
"We received an average of 13.35 inches of precipitation on the Salt and Verde watershed from December through May, which was the 10th wettest winter in the years we've keeping these numbers," said Ester. "What that means is our system is operating just as it is supposed to, capturing runoff in wet years like this one and storing it for the dry years we know will be returning."
Ester said several records were broken this past winter, including the most precipitation for one day ever on the watershed. On Jan. 21, 3.76 inches fell on the watershed over a 24-hour period, easily breaking the previous single-day record of 2.34 inches. Several other records fell during that series of three storms that deluged central Arizona, including the six-day mark of 6.76 inches from Jan. 18-23.
Roosevelt Lake, which filled up to a record elevation of 2,152.08 feet on April 26, today stands at elevation 2,149.44. Roosevelt accounts for about two-thirds of SRP's storage capacity and is the largest of the Salt and Verde reservoirs, which store the majority of surface water delivered to the greater Phoenix metropolitan area.
Once warm temperatures finally arrived and melted the snowpack on the watershed, SRP halted releases into the Salt River through the Phoenix area on May 27. The total spill from Granite Reef Diversion Dam from mid-January to late May was 668,061 acre-feet.
But do all of these records, along with the fact that we've had three consecutive years of above-normal runoff, mean that the drought that has dogged central Arizona since 1996 is a thing of the past?
"Is the drought over? That's a great question that we get asked all the time," Ester said. "Now, if we were to have another wet winter next year, I might say the drought is over locally, but when you look at the entire picture of the Southwest, with the Colorado River receiving below-normal runoff in an El Nino year like this, I'm not ready to declare the drought over just yet."
SRP is the largest raw water supplier in the Phoenix metropolitan area, normally delivering more than 1 million acre-feet annually.
