The Cascades are losing the snow that normally would help recharge the Yakima River during summer months, making a drought more likely and possibly worse.
Record high temperatures in the Cascades mean snow is melting daily, cutting into an already critically low snow supply.
And the snow is melting early, which could lower water supply expectations for Yakima River water users. Already, the federal Bureau of Reclamation predicts some Yakima Basin irrigation districts may receive about 73 percent of their normal water.
Irrigation districts that could see their water use cut back include Kennewick and Roza. Benton and Sunnyside Valley irrigation districts have some water the government can’t limit, but they also have some water that can be cut back in a drought year.
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Having snow melt at the right time is key, since it typically fills the river during the summer so that water demands can be met for Mid-Columbia towns, crops, fish and lawns.
The five reservoirs that serve the Yakima Basin are nearly full but don’t hold enough water to fill demand. The reservoirs typically will be drained and refilled twice in a normal year, but the lack of snow and what little snow there is melting early means that may not happen.
Scott Pattee, U.S. Department of Agriculture water supply specialist, said he is concerned that snow in the Cascades already has gone into a permanent melt phase that is difficult to stop. Usually that doesn’t happen until sometime between April 1 and 15.
The snow stacks in layers during winter months, but later transforms into a single layer with the same temperature throughout, he explained. At that point, the base of the snow begins to melt.
“These temperatures are just killing us, and I don’t see a break in sight,” Pattee said. The nighttime low temperatures in the Cascades have been around 45 to 55 degrees and the snow buildup is fairly shallow.
No measurable amount of snow accumulated last month. A light dusting of snow occurred on elevations above 4,000 feet, according to the USDA.
More than 27 percent of the agency’s snow telemetry stations and snow course networks set new all-time record lows or near-record lows for snow water equivalent for March 1. Snow water equivalent measures how much water can be expected when the snow melts.
Overall, a warm and dry spring is expected, although it’s difficult to predict weather more than 10 days out with any certainty.