EVERETT — Zero. That’s the depth of snow in the Sultan River basin. It was measured Thursday by Snohomish County Public Utility District staff members.

When the helicopter flew into the basin around Spada Lake, Mark Flury, the lead engineer of the PUD’s generation division, could only see patches of snow at higher elevations. Lower down, the ridges were completely bare, he said. “I was a little bit surprised.”

Since it started a yearly survey in 1986, the PUD has never recorded zero snowpack.

But Flury isn’t worried.

It’s been a warm and wet winter. So there has been plenty of rainfall, if little snow.

The water level in Spada Lake Reservoir, which provides the county with 80 percent of its drinking water, is 106 percent of what it was at this time last year, said Marla Carter of the city of Everett’s Public Works Division.

While the PUD manages the Jackson Hydroelectric Project and Culmback Dam around the lake, the city manages the system that delivers drinking water to most of the county.

PUD staff members measure the snow level each March by sinking a long, hollow tube marked with inches and feet into the snow to determine the depth. They pull it out and weigh it with a handheld scale to determine how much water is in the snow trapped in the hollow tube.

This year, they could have left the tube and scale at home.

“There wasn’t any snow except for infrequent patches,” Flury said.

Measurements are collected at three elevations: 2,400 feet at Kromona Mine, 3,300 feet on Olney Ridge and 3,600 feet on Stickney Ridge.

Zero snow has been recorded at individual locations in a given year, but the PUD has never had zero snow at all three.

In 1986, there was no snow at Kromona Mine, the lowest-elevation site. In 1992, there was no snow again at that site, or on Olney Ridge. The next year, PUD staff again didn’t find snow on Olney Ridge, but there was nearly 34 inches at the lower elevation and 64 inches on Stickney Ridge.

Despite the record-low year, the PUD “won’t propose any changes” immediately to how much water flows out of Spada Lake, Flury said.

The lake is a huge reservoir that can hold about 50 billion gallons. That is more than 10 percent of all the water used in the U.S. in one day, according to the U.S. Environmental Protection Agency.

After the wet winter, neither the PUD nor the city expect to run short of water.

Dan Catchpole: 425-339-3454; dcatchpole@heraldnet.com; Twitter: @dcatchpole.