TWIN FALLS — Idaho is having a drier-than-normal winter, which could cause significant drought conditions in the Magic Valley this summer.
This is a La Niña year, which typically means heavy rains and snow in the Pacific Northwest and low precipitation south of Idaho in the Great Basin, Colorado Basin and southern California.
Sometimes though, the La Niña weather pattern can lead to drought conditions.
“The drought that is typically centered in Colorado and the Great Basin is pushing a little further north than it typically does,” Idaho Department of Water Resources Hydrologist David Hoekema said.
Relative to the rest of the West, Idaho is in good shape. The National Oceanic and Atmospheric Association’s drought monitor shows most of Utah, Arizona and New Mexico in “exceptional” drought — that’s the most severe designation. In comparison, southern Idaho is mostly “abnormally dry” or in “moderate drought” — the two mildest categories.
The last few years have been wet in Idaho. But the state cycles between wet and dry periods. There are signs that Idaho is about to enter a new dry cycle, Hoekema said, although that could all change with a wet winter next year.
As of Monday, basins in our region had all received significantly below-average precipitation. The Salmon Falls Basin in southern Twin Falls County has received just 70% of its average precipitation, while the Goose Basin (74%) in Cassia County and Little Wood Basin (76%) in Blaine County aren’t faring much better. There’s still plenty of winter left for a big storm to replenish snowpack, but if the storms don’t come, certain parts of the Magic Valley could experience an impactful drought.
If the winter doesn’t get wetter, south-central Idaho ranchers and dry-land farmers would be the first to feel negative impacts.
But most Magic Valley farmers aren’t in much danger of seeing water shortages in 2021, for a couple of reasons.
For one, farmers here mainly water their crops via canal systems which in turn rely on the Snake River. The Snake is fed by snowmelt from high mountain ranges in eastern Idaho and western Wyoming — including the Teton Range. The mountains that feed the Upper Snake have gotten nearly average snowfall this year — in the 90% range.
A couple of weeks ago, it was a different story. Twin Falls Canal Co. General Manager Brian Olmstead said those mountains had only seen about 79% of their typical precipitation.
“It was looking really concerning,” Olmstead said.
The Twin Falls Canal Co. has been relatively fortunate in recent years. Olmstead said farmers haven’t been short on their water deliveries since 2007.
In addition to the eastern Idaho and western Wyoming mountains getting good precipitation, Idaho’s reservoir system also protects farmers. Some reservoirs are less full than normal — for instance, Hoekema said the Oakley reservoir might not have a full water supply this year.
But Brian Stevens, the Bureau of Reclamation’s Upper Snake Field Office water operations manager, said reservoirs on the eastern side of the state are in good shape, for the most part.