Some years, there is a lot of snow in the Cascades, and some years there isn’t as much.
Then there are years when the snowpack is about average. This is one of those years, according to the Snohomish County Public Utility District.
The utility did its annual measurement of the snowpack, and its water content, in the upper reaches of the Sultan Basin last week.
A couple of PUD staff members take a helicopter to the same three places in the Sultan Basin every March to measure the snow, said Bruce Meaker, a principal engineer for the PUD.
A rainy or dry spring can alter the outlook a bit, but the testing helps utility staff determine how to manage the water flow from Culmback Dam and pipelines at Spada Lake, he said.
If they know a lot of melted snow is coming down the mountain, they release more water from the lake to make room for the water that’s coming. If they expect less, they release less.
Also, about 80 percent of the drinking water for Snohomish County comes from Spada Lake via Lake Chaplain to the city of Everett. This year’s snowpack will help ensure a normal supply for the summer, said Dave Davis, city of Everett public works director.
“We do not anticipate any water restrictions over the course of the summer,” he said. Still, Davis encouraged residents to conserve water when possible and to follow the city’s recommended sprinkling calendar provided in water bills.
The Sultan Basin drains to Spada Lake, where the PUD operates the dam and the Jackson Hydroelectric Project.
The utility generates close to 5 percent of its power by running water from Spada Lake through a pipeline to turbines in a pumphouse 4 miles downstream from the dam on the Sultan River.
There, the four turbines generate enough power for about 35,800 homes.
In high-flow years, the PUD can generate more power through the turbines; in low-flow years, less, Meaker said.
The utility has tested the snowpack every year since 1986 and kept records. This year, there was more snow than average, and a higher water content than average, in two of the three locations.
While the numbers were above normal at two of the three sites, Meaker figures it amounts to about average because most of the drainage basin is at lower elevations.
The highest spot, Stickney Ridge at 3,600 feet, had 115.5 inches of snow, or nearly 10 feet, Meaker said. That’s 118 percent of average since 1986, he said.
The second highest spot, Olney Pass, at 3,300 feet, had 60 inches of snow, or 5 feet, which is 121 percent of normal.
The water content at both Olney Pass and Stickney Ridge was above average, Meaker said.
The lowest site, the Kromona Mine at 2,400 feet, had 41.7 inches of snow, only 79 percent of average, and the water content was below average.
It’s unusual, he said, for some numbers to be above average and others to be below.
The snow is measured with a long tube marked in inches and feet. The tube is weighed with a hand-held scale to determine the water content, Meaker said.
“It’s a very simple, low-tech way to do this,” he said.
The testing is done this month every year because the snow accumulates all winter and usually hits a peak no later than March, Meaker said.
“I’ve never seen it accumulate after the middle of March,” he said.
Bill Sheets: 425-339-3439; sheets@heraldnet.com.
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