Traditionally the April 1 snow survey marks the peak of the year’s snowpack, but with a string of early spring storms surveyors are rushing to measure the pack with just days to get their measurements in. Valley Public Radio reporter Ezra David Romero helped in the effort as a snow surveyor on a recent trip.
At 6,000 feet Christine Bohrman, our pilot and I hop out of a helicopter into a snow laden meadow below Courtright Reservoir in the Sierra National Forest.
Bohrman is a hydrographer for Pacific Gas and Electric and is part of a network of snow surveyors tallying water content in the Sierra Nevada. We’re on one of the last snow survey flights of this season, measuring the meager snowpack in the Kings River watershed.
The data collected in this survey will be used by PG&E and others to estimate just how much snowmelt we can expect this spring. Even in a normal year it’s an important job. But in a drought like this one, she says these measurements are even more critical.
"This year since we have a dry year, just like we’ve had for the past two years, the last wet year was in 2011," Bohrman says. "So the accumulation of three dry year’s means there wasn’t much water storage from the previous years, not much carry over.”
As we hike from the helicopter to the first survey site, our snowshoes crunch over the snowpack that will soon feed into reservoirs like Courtright and Wishon for energy production. The water will eventually flow into the Kings River and down to the San Joaquin Valley supplying water to farms and cities like Fresno. Snow surveys like this go back decades.
“If you take a look at the map you can tell this course has been here since 1928, so it’s been here for quite a while and the idea of a snow course is that you want to have repetitive data," Bohrman says.
Bohrman assigns me the task of recording the survey data, while our pilot measures the distance between survey spots.
“So what I am doing is lining myself up with the aerial marker and the orange sign," Bohrman says. "I’m trying to get myself on the invisible line between the two points.”
She then pierces the snow with a hollow aluminum tube that can expand to over 14 feet.
"I want to be able to get a piece of grass or dirt to know that I've hit bottom instead of an ice layer," Bohrman says. “This is a marshy area and there’s a lot of melted snow that’s why you’re seeing water dripping from it.”
Bohrman weighs the snow tube and compares its weight to its empty state.
"49, so eight inches of water content," Bohrman says.
From our first survey point we travel to another meadow at 9,000 feet but the weather takes a turn for the worse.
“It looks like we’re getting snowed in and getting heavier clouds coming so we’re gonna be safe and get out of here," Bohrman says.
Bohrman’s monthly readings help PG&E decide how much water they should release from reservoirs, how much hydropower the company can produce and how the watershed she measures will contribute to the statewide snowpack.
“We have a lot less water then we normally would, normal being the average for about 50 years," Bohrman says. "We’re at about 20 percent of the normal so we do have to watch what we do with the water."
That’s on par with previous drought years. She also says by looking at how agencies used water in past droughts, we can learn how to best utilize the little water we have.
“76 and 77 was a dry year as well," Bohrman says. "As far as I know PG&E was out doing snow surveys at that time too and was able to manage water going into reservoirs and still had enough water to meet the demands of customers.”
Bohrman says that while surveys like this one show there may be enough water for PG&E’s purposes this year, only time will tell if valley farms and cities will be as fortunate.