SRP’s Reservoir System Captures about 120 Billion Gallons of Water During Historic Runoff Event

Recent storm systems brought significant rainfall and runoff across central Arizona, which generated substantial inflows into the Salt and Verde River reservoir system and helped replenish water supplies following several years of dry conditions.

At the peak of the event, inflows into the Verde River reached an estimated 94,000 cubic feet per second, while combined inflows into Roosevelt Lake peaked at approximately 145,000 cubic feet per second. That’s about 703,000 gallons of water per second and 1 million gallons of water per second, respectively.

In total, SRP was able to store about 370,000 acre-feet of water or 120 billion gallons of water in SRP’s reservoir system from the storms, increasing the storage from 53% full on Nov. 1 to 70% full on Nov. 6.

This is lining up to be a record-breaking fall for precipitation and inflows in the Salt and Verde River watersheds after three consecutive, low-runoff seasons. October and November inflows are the highest on record on the Salt and Verde watershed, about eight times greater than average.

As inflows have slowed, releases from the SRP reservoir system have been returned to normal operating ranges.

“The reservoir system performed exactly as designed, capturing and storing a significant amount of runoff that will help support water deliveries for the Valley while allowing us to conduct safe releases to ensure dam and public safety,” said Tim Skarupa, Senior Manager of Atmospheric Sciences and Hydrology.

During the storm event, SRP made controlled releases from several locations within its water system to safely manage flood flows and protect infrastructure. Flows over Granite Reef Diversion Dam and other facilities were necessary to move water through the system, maintain safe operating conditions and prevent impacts on canals and other infrastructure.

SRP will continue to closely monitor weather, watershed and reservoir conditions and will adjust releases as needed.

Unlike the Colorado River system, which has been facing shortages due to the ongoing drought, the Salt and Verde reservoir systems are nearly in balance where annual demand is close to the annual supply. However, in wet years such as this year, runoff can exceed the available capacity of the reservoir system.

Some benefits from the releases include a recharge of the aquifer as it traveled through the Valley while Valley cities and water providers and cities and irrigation districts were able to take deliveries from the releases.

Several roads located in the East and West Valley that were built in the normally dry Salt River riverbed may continue to be closed. Updated road information can be found on the ADOT website at AZ511.com.

SRP is currently evaluating alternatives on increasing the storage capacity and mitigating future storage losses due to sedimentation for the Verde River reservoir system. A group of 23 partners, including tribal, agricultural and municipal organizations have committed to support the Bureau of Reclamation (Reclamation) feasibility study of options to modify Bartlett Dam to improve management of water resources provided by the Verde River.