Low snowpack impacts Phoenix water reservoirs

Results from a new airborne snow survey over northeastern Arizona found that due to a dry and warm winter, most of the snow water measured in January and February had melted by mid-March, offering water managers an unusually clear view of how quickly the season changed.

Arizona’s mountain snowmelt provides a significant portion of the Phoenix metropolitan water supply. For SRP, even small changes in mountain snowpack can affect how much water eventually flows into reservoirs during the spring melt season.

Information about how much, or in this case how little, snow remains will help SRP hydrologists decide by early summer where to store water and how much groundwater they will need to use.

Enrique Vivoni, the director of the Center for Hydrologic Innovations at Arizona State University, joined Arizona Horizon” to discuss the latest findings.

“We’re mapping an area called the upper Black River,” Vivoni said, “…it’s a watershed that provides streamflow to the Salt River, and we manage it at Roosevelt Lake, so it’s a water supply source.”

Vivoni emphasized how the snow in this region is an important component of the water supply coming into the SRP system. He also explained how the dry and warm winter is not just impacting the state, but most of the Western United States.

“If you recall,” Vivoni discussed, “…we had a heat wave in March here in the valley, and in the northern country, and that heat wave really got to the snowpack really quickly.”

According to Vivoni, in January and February, there was about 9,000 acre feet of water, which could supply roughly 28,000 homes for a whole year.

“Now that snow water is in the ground,” Vivoni explained, “…it’s making its way down into the river to become water supply for the valley.”

Vivoni also discussed how it wasn’t unprecedented that the number dropped more than 90%, as snow melts much quicker here than it does in other states. He did explain how it was surprising that it essentially collapsed in a matter of a few days.