'Weather chaos' brings enough snow to fill Verde River reservoirs, ease drought conditions

HAPPY JACK — Meteorologist Bo Svoma hopped down into the 4-foot-deep pit he had shoveled and grinned like a school kid on a snow day.

“Bo is happy!” shouted one of his Salt River Project colleagues working snow survey duty on Tuesday.

There’s a lot for the metro Phoenix water supplier to be happy about this winter. What was supposed to be an unusually dry winter because of the return of the ocean and atmospheric phenomenon known as La Niña has instead shaped up as the Arizona rim country’s second-snowiest season in 30 years. The ocean conditions that usually would push the jet stream and its storms toward the Pacific Northwest instead have driven storm after storm into the Southwest.

“It’s weather chaos,” Svoma said.

Arizona will take it, battered as the state has been by drought over the last two decades. The snow that Svoma and colleagues measured at their routine sampling site in Happy Jack — a forested outpost between Flagstaff and Payson — will in coming weeks join big snows elsewhere in the Verde River tributaries and start flowing across miles of terrain and 6,000 feet downhill to the desert dwellers in and around Phoenix.

Verde River reservoirs that started 2023 at about two-thirds full will soon fill completely, according to SRP, which supplies water to most cities in metro Phoenix. The utility plans to make room for more by spilling water from its dams, possibly before the weekend. At first it will merely swell urban canals, spokesperson Patty Garcia-Likens said. As March progresses, further snows and rains could lead to bigger spills that will enter the dry Salt River bed and sink in to replenish an aquifer that has helped the region get through drought.

The Salt River side of SRP’s water supply will likely come close to filling its reservoirs, the largest of which is Roosevelt Lake, SRP hydrologist Stephen Flora said. Between the two watersheds, there’s about 1.1 million acre-feet massed and ready to pour toward the desert. Each acre-foot is roughly 326,000 gallons and can supply about three households for a year.

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Even with snow, questions linger on the Colorado River

It’s been three years since the system filled this well. It doesn’t mean residents should ease up on water conservation, though, as Flora noted that the Colorado River’s outlook is much less promising. The big river usually supplies about a third of Arizona’s water, but drought has brought reductions to the portion flowing through the Central Arizona Project Canal.

Although the Rocky Mountain snowpack that melts each spring and summer to supply the Colorado is currently above normal for this time of winter, it’s far from clear what will happen in summer. Recent winters that piled up near-normal snowfall in the Rockies delivered scant flows toward Lake Powell and Lake Mead, the nation’s two largest reservoirs. A combination of dry soils and warming atmosphere wicked away much of the water that hydrologists hoped would help replenish the lakes, now just 23% and 29% full respectively.

Even if this year is different and soil moisture accumulated from summer and fall rains ease the path for more of the snowmelt, it would take several successive years to refill those massive reservoirs, Flora said.

“We live in a desert,” he said. “Water is a precious resource.”

The Salt and Verde are less susceptible to warming’s ravages, Flora said, because their smaller reservoirs can fill before the heat of summer evaporates it or causes trees to transpire more of it. The Colorado’s elevated headwaters usually hold their snow until the sun is high overhead and ready to take its share.

A good winter like this one allows SRP to plan on using more water from its reservoirs while giving wells a break. With luck, the groundwater can rebound some before the next time the reservoirs are low.

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How deep is the snow and how much water is in it?

For Tuesday, though, it was happy time in the snow. In recent decades, only the winter of 2009-2010 had piled northern Arizona’s snow deeper.

Flora, Svoma and field hydrologist Zac Keller snowshoed into the ponderosa pine forest off Lake Mary Road and took turns jabbing a 60-inch-long tube into the snow in four places around an automated snowpack measuring device. Their measurements would verify the automated station’s remotely gathered data, helping SRP plan its dam operations with the upcoming melt in mind.

Svoma started by jotting down the data, and might normally have left the jabbing to Keller if not for the unusual depth.

“I want to do a measurement because that’ll be the most I’ve ever done,” Svoma said.

The automated device is like a round, 15-foot-diameter pillow filled with antifreeze to keep it thawed and buoyant under the snow. The weight of the snow pushes some of the fluid up through a tube, giving a reading that approximated the snow’s water content. On this day it said the snow contained the equivalent of 14.8 inches of water.

The men lifted tubes partially filled with snow — 48.5 inches in one corner, 50.5 inches, 47 inches and 51 inches in the others — and weighed them from a hanging scale. A little math brought them to an average water equivalent just shy of 15 inches, nearly identical to what the automated gauge had suggested.

The U.S. Natural Resource Conservation Service operates the automated stations, called Snotel sites, and comes out to check them about once a month. SRP also checks monthly on an array of them spanning from south of Williams to Hannigan Meadows, near the New Mexico state line. The solid data twice a month can help SRP plan its operations.

Svoma dug his snow pit not just for fun, but to read the temperature beneath the surface. The snow appeared close to freezing, after having been colder, in the 20s Fahrenheit, during a January reading. It meant this snow’s water likely would soon start flowing toward the Verde.

But in the forecast for Wednesday was more snow above the Mogollon Rim.

“I love snow,” Svoma said.

Brandon Loomis covers environmental and climate issues for The Arizona Republic and azcentral.com. Reach him at brandon.loomis@arizonarepublic.com or follow on Twitter @brandonloomis.

Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow The Republic environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.

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