Salt River Project has begun releasing excess water from its two reservoirs on the Verde River, just north of Fort McDowell and the Verde Communities, to create additional storage capacity and provide maximum flexibility for snowmelt and the likelihood of future runoff events this spring.

The recent cold storm significantly added to the snowpack on the Salt and Verde watershed, and the forecast of additional storms prompted a low-level spill release beginning Feb. 28, of about 15 cubic feet per second of water from Granite Reef Diversion Dam, which is located just west of the confluence of the Salt and Verde rivers. The Granite Reef release was scheduled to be increased to at least 500 cubic feet per second by late Saturday, March 2.

Bartlett Lake, the larger of the two Verde River reservoirs, and Horseshoe Lake will soon be reaching near capacity from snowmelt with only about 35,000 acre-feet of available space between the two lakes. The total Verde River storage system today is at 86 percent of capacity, up from 31 percent in mid-December. Horseshoe Lake is currently at 91 percent of capacity and Bartlett Lake is 83 percent full.

The combined Salt and Verde system today is at 63 percent of capacity, up from 61 percent one year ago. There is significantly more storage available on the Salt River, which is 59 percent full. Theodore Roosevelt Lake, which holds about two-thirds of the water SRP stores, was at 51 percent last week – up from 40 percent on Jan. 1 and an increase of more than 150,000 acre-feet.

Additionally, the return to a more normal winter weather pattern has also filled C.C. Cragin Reservoir, near Payson, which reached capacity in mid-February and started spilling into East Clear Creek. Cragin, located on one of the most productive watersheds in Arizona, fills about 70 percent of the time and last reached capacity in 2017.

Charlie Ester, SRP’s manager of surface water resources, said the recent cold storm and resulting snowmelt – as well as the forecast of warmer temperatures and additional spring storms – have the potential to greatly exceed expectations in terms of runoff production as was anticipated a couple of weeks ago. Releasing water from Bartlett Dam on the Verde River, he said, is one of a number of preemptive actions being considered. Groundwater pumping and most Central Arizona Project water delivery is being curtailed until after this stormy period.

Ester said the forecast for continued warmer temperatures will add to current inflow on the Salt and Verde watershed and having a low-level spill in place already allows maximum flexibility to deal with future runoff events. He said the Verde snowpack is currently about 140 percent of normal while the Salt is 107 percent of normal as this week’s dry and warmer weather has already prompted some of the lower snow to melt. While the snowpack has been significant on both the Salt and Verde watersheds, Ester said Theodore Roosevelt Lake – with nearly 800,000 acre-feet of available space, can easily absorb additional runoff.

Ester said the start of Verde River releases means the normally dry Salt River could be flowing through the Valley the rest of the runoff season. The last time SRP spilled water at Granite Reef Dam into the Salt River was in 2017. 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 planning water releases.

This winter’s storms have been a welcome sight for SRP, which in 2018 saw the driest runoff season since it began record keeping about 120 years ago. In fact, the two-day runoff amount of 108,000 acre-feet into the Salt and Verde reservoirs from the Feb. 14-15 storm exceeded the entire total from the 2018 runoff season (Jan. 1-May 31) of 100,000 acre-feet.

SRP’s current streamflow forecast is projecting the 2019 runoff to come in at more than 850,000 million acre-feet. The last two wettest winters came in 2017, when nearly 1 million acre-feet of runoff filled the Salt and Verde reservoirs, and 2010, with 1,430,000 acre-feet of runoff.

SRP is the largest raw water supplier in the greater Phoenix metropolitan area, delivering about 800,000 acre-feet annually to agricultural, urban and municipal water users.