Water year off to ominous start
LEWISTON – The start to the 2024 water year has been wet, but as weather watchers know, the moisture has largely fallen as rain, leaving mountain snowpacks well below average.
In Idaho, the Clearwater River Basin has a snow-to-water equivalence that is just 52% of average. The Salmon River Basin sits at 62% and the lower Snake River Basin in southeastern Washington and northeastern Oregon, including the Blue Mountains, has a snowpack that measures 61% of average.
Most regional ski areas are operating but with only a fraction of their terrain open. Snow that piles up in high elevation areas during the winter months is counted on to help flush juvenile salmon and steelhead to the ocean, provide irrigation water to farmers in southern Idaho and central Washington and keep turbines spinning at hydroelectric dams. When snowpacks are short, all those various uses of water that runs off as snowmelt in the spring and summer compete against each other.
The water year starts Oct. 1 and runs through September. This year started with an October and early November dry spell. But since then, seven atmospheric river events have sent heaps of rain to the Inland Northwest.
Kyle Dittmer, a hydrologist and meteorologist with the Columbia River Inter-tribal Fish Commission, said the abundant rain is helping to ease drought conditions that are measured in terms of soil moisture. But there is a considerable downside.
“We’ve been getting an abundance of moisture, which is good and, of course, helping to erase the drought,” he said. “What we really need to be having is moisture in the form of snow for the water supply to really work.”
An El Nino weather pattern is in force this winter. That often means above-average temperatures and lower snowpacks. Dittmer said El Nino and La Nina weather patterns are becoming more erratic and harder to predict. For example, last year’s La Nina was unusual in that it delivered a water supply well below average. Dittmer believes even though there is an El Nino pattern in place this year, there is a chance there will be more water available compared to last year.
That could depend on a late surge of moisture. Many El Nino years are front-loaded with moisture and then followed by a dry spell. In some years, storms come roaring back in March and April and help save the water year. Given the unpredictability of El Nino events, Dittmer said it’s possible January and the following months will bring abundant mountain snow.
He cautions that the longer the dry spell lasts, the deeper the water supply deficit gets.
“We need to actually have a lot of vigorous storm activity fairly often between now and the end of March to even get back rebuilding our snowpack,” he said. “And that’s the problem – the further we get into the season, it’s going to get harder and harder to reverse that trend and make it get back even toward some resemblance of normal.”