SRP begins water releases through Salt River
Storage space needed as snowmelt will soon fill Horseshoe, Bartlett lakes
This weekend’s forecast of a return of wet weather to northern and central Arizona has prompted Salt River Project to begin releasing excess water from its two reservoirs on the Verde River to create additional storage capacity and provide maximum flexibility for likely future runoff events.
A low-level spill release of about 500 cubic feet per second was initiated this afternoon from Bartlett Lake on the Verde River, which is reaching near capacity from snow melt with only about 32,000 acre-feet of available space. The total Verde River storage system today is at 87 percent of capacity, up from 45 percent in mid-December. Horseshoe Lake is currently at 94 percent of capacity and Bartlett Lake is 82 percent full.
The combined Salt and Verde system today is at 64 percent of capacity, up from 55 percent one year ago. There is significantly more storage available on the Salt River, which is 61 percent full. Theodore Roosevelt Lake, which holds about two-thirds of the water SRP stores, is at 53 percent today – up from 35 percent on Dec. 15 and an increase of nearly 500,000 acre-feet since mid-December.
Charlie Ester, SRP’s manager of Surface Water Resources, said the forecast for this weekend will add to current inflow on the Salt and Verde watershed and that having a low-level spill in place already allows maximum flexibility to deal with the weekend storm and future runoff events. He said the Verde snowpack is currently about 140 percent of normal while the Salt is 76 percent of normal as the recent dry and warmer weather has already prompted some of the lower snow to melt.
Ester said the Verde River release means the normally dry Salt River will be flowing through the Valley the rest of the runoff season. SRP in late January released water over Granite Reef Dam into the Salt River for a few days because of local inflows below Stewart Mountain Dam on the Salt River and Bartlett Dam on the Verde River. The most recent significant water release through the Valley was in January 2010.
Recent SRP surveys have determined that snowpack on the 13,000-square-mile watershed that replenishes the six Salt and Verde river reservoirs is the deepest it’s been in nearly two decades, according to measurements taken recently by a team of SRP hydrologists. SRP officials regularly check the snow levels in Arizona’s high country during the winter to develop seasonal runoff forecasts and provide valuable data for flood-control planning.
This winter’s storms have been a welcome sight for SRP, which in 2016 saw a sixth consecutive below-median runoff season for the first time in its 119 years of record keeping. That streak will likely be snapped this winter, according to Ester.
SRP’s current streamflow forecast is projecting the 2017 runoff to come in at more than 1 million acre-feet. The last wet winter came in 2010, when 1,430,000 AF of precipitation filled the Salt and Verde reservoirs.
After an early El Nino forecast of more than 1 million acre-feet in 2016, last year’s runoff wound up producing 338,181 acre-feet – the unprecedented sixth consecutive year of below-median runoff. Over the previous five years, the final runoff season numbers were 328,360 AF in 2015; 148,000 AF in 2014, the eighth-driest since SRP has been keeping records for the last 118 years; 444,788 AF in 2013; 196,064 in 2012; and 222,907 in 2011.
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SRP is a community-based, not-for-profit public power utility and the largest provider of electricity in the greater Phoenix metropolitan area, serving more than 1 million customers. SRP also is the metropolitan area’s largest supplier of water, delivering about 800,000 acre-feet annually to municipal, urban and agricultural water users.