Thursday, March 28, 2024

Lake Chelan Basin snowpack 80 percent of normal

How does PUD measure snowpack?

Posted

CHELAN – In a recent preliminary forecast survey conducted by a team of Chelan PUD specialists, it was found that the Lake Chelan Basin is currently at 80 percent of water supply for the year.

Compared to last year’s forecast it was a little below average, however as energy analyst John Wasniewski states it’s still early and a lot more snow could develop this winter. It’s hard to predict the amount of snow each year because each year is unique. Based on historical data Wasniewski has seen a wide variety of range levels. “There are years were it may show 80 percent in February and it ends up being above average and other years it may not work that way,” he added.

Temperatures, weather and precipitation will determine when Lake Chelan will start to refill with melted snow. This generally occurs during April or May. July 1, is the date PUD tries to achieve having the lake at capacity for the summer, which equals 1,098 feet in depth.

Wasniewski and his team measure the snowpack from three different locations above Stehekin. “We go to Park Creek Ridge, back up northwest of Stehekin. That’s one indicator. We also go to Lyman Lake which is the headwaters for Railroad Creek up above Holden,” he explained.

Those two places are used year after year to get snowpack measures. “We plan three trips per year, one in February, a March one and an April one,” said Wasniewski. Sometimes the helicopter can’t make it to the sites due to the weather.

Three PUD staffers fly to the sites where the snowpack survey is conducted. Two staffers screw together a set of aluminum tubes to measure the snow depth. “We try to pull out a core of the snow melt all the way from the dirt up to the top and measure the length of the core.” The third staff member is usually the team’s scribe. The snow collected in the tube then is weighted, the weight of the tube gets subtracted in order to calculate the exact weight of it.  

“The weight of the snow itself it’s what gives us the water content, the water content is the most important number,” said Wasniewski. The team spends around 20 to 30 minutes and take four samples at each of the sites they visit. A whole trip usually takes four to six hours. From there it takes a couple of days to analyze the data collected.

Once a week, Wasniewski writes a brief narrative on what he is seeing at Lake Chelan. He publishes his writing on the website www.chelanpud.org/parks-and-recreation/lake-chelan-lake-levels. The website includes a graph that shows the current level of the lake at a real time.
 

Comments

No comments on this item Please log in to comment by clicking here