Growers in Idaho are wondering what the coming year will bring as far as precipitation. Speculation on how much snowpack we’ll receive before this winter is over will only take us so far.
Water experts in the Gem State seem to agree that the drought last summer and the light snowpack we received last winter didn’t put us that far behind; however, what the remainder of this winter and coming summer bring is a different story.
Lyle Swank, eastern regional manager and watermaster for the Idaho Department of Water Resources, says that the good thing about 2012 was the amount of reservoir carryover Idaho had from 2011.
“The reservoirs are built for both irrigation and flood control. On a year like 2012, they really, really help to save people who were depending upon that late-season storage,” he says.
However, following a winter of light snowpack was a hot, dry summer with high demand for water.
“You get a hot, dry year, and suddenly you don’t just have average demand—you’ve got above-average demand,” Swank says.
Still, the reservoirs were a saving grace, although he points out that if there weren’t reservoirs, it’s possible that growers wouldn’t have planted as many acres.
Mike Beus, water operations manager for the Upper Snake Field Office at the Bureau of Reclamation in Burley, says we didn’t receive a severely low snowpack last winter—run-off was somewhere in the 80 percent range.
“What really caused the big drain on our water supply, especially the storage, was the early warm weather and continued dry [spell] through the spring and summer, resulting [in a] very long season,” he says.
Beus points out that there are a couple twists to the statistics. This year, the 30-year climate period is shifting up a decade, changing what we consider as “normal.”
Compared with the 1971–2000 averages being used through last year, we were 81 1/2 percent of normal. When compared to the updated 30-year time period of 1981–2010, last year was 89 percent of normal.
In general, it wasn’t a bad year; however, storage has been depleted much more than would usually be depleted in a single dry year.
“That doesn’t set us up well for this year,” Beus says.
Swank says that if we have a repeat this winter of the same snowpack as last winter, we’re not going to be able to fill the reservoirs, “unless we get an awful lot of rain or have a real good spring as far as precipitation.”
He’s hopeful because precipitation in the spring can make a difference, like in the year 2009.
“You can go from almost certain you’re not going to fill, to suddenly filling after the spring.”
During late fall 2012, they’ve been storing as much water as they can—operating the reservoir system for near-optimum fill through the end of winter—but it will still be challenging.
“It’s going to be a lot more difficult to fill Palisades Reservoir, and Jackson Lake Reservoir is also lower this year than it was a year ago,” he says.
Beus agrees this upcoming season could be challenging.
“If we get 89 percent, the same volume of water we had last year and have a low reservoir system coming in, there are some crops that won’t get water as early next year as they did this year.”
Beus says that consecutive 80-percent years are not too difficult in and of themselves—until we continue to increase the marketing demands on the water supply, such as the federal regulations through the Endangered Species Act for anadromous fish—fish such as salmon and steelhead, which are born in fresh water, spend most of their lives in the sea and return to fresh water to spawn.
Beus says they’ll be watching the snow accumulation carefully.
“It would be very nice if we had a 110–120 percent snowpack, and could transition to a flood operation in February. Bigger than that gives us a whole polar opposite set of problems to deal with,” he says.
Swanks says that there are studies currently under way in the Gem State for additional water storage. They’re looking at not only rebuilding a dam at the Teton Dam site, but also a few small, off-site locations that would add a nominal amount of water storage, as well as raising a nearly century-old dam near Ashton, Idaho.
One positive Swank sees is that the winter going into 2013 started with a little bit of snow in the high elevations, though there’s still a long way to go.
As of mid-November, the Upper Snake River system—consisting of Jackson Lake, Palisades, Grassy Lake, Island Park, Ririe, American Falls and Lake Walcott Reservoirs—were at 33 percent of capacity.