YAKIMA, Wash. — Recent rain and snowstorms have brought Yakima Basin reservoirs back up to where they should be at this time of year after hitting their lowest levels in years because of drought.
The reservoirs reached 100 percent of normal on Nov. 18, increased to 105 percent on Nov. 21-23 and then dropped back to 100 percent by Nov. 30, said Chris Lynch, hydrologist for the U.S. Bureau of Reclamation’s Yakima Project.
“I’m pleased that we’ve gained that much storage. We dramatically gained ground in the past month, so that’s a positive,” Lynch said.
It’s not particularly surprising because a few good storms can do that, he said. Similar gains occurred a year ago from a few early-season storms, he said.
The five reservoirs — Keechelus, Kachess, Cle Elum, Bumping and Rimrock — have a combined capacity of a little more than 1 million acre-feet of water. Usually, they don’t fill until May or June from melting snowpack.
More rain than snow at low elevations this winter could cause the peak level in April or May to be short of full, Lynch said.
Sufficient snowpack is more critical for enough irrigation water next summer than having the reservoirs full at any given point. Irrigators on 464,000 acres, mostly farmland, in the Kittitas and Yakima valleys depend on 1.7 million acre-feet of water annually. Usually 1 million acre-feet is stored in the reservoirs and 2.3 million acre-feet is in the snowpack that melts in spring and summer and mostly feeds the reservoirs.
The reservoirs hit a season-ending low of 107,000 acre-feet on Oct. 28, compared to 330,000 last year and a 30-year average of 270,000.
As of Nov. 30, the reservoirs were at 387,000 acre-feet.
“So we gained about 280,000 in about a month,” Lynch said. Typically, the reservoirs gain after storms and then level out. They drop below average again when enough days pass without new moisture, he said.
Two large irrigation districts, Kittitas Reclamation and the Roza, received about half their normal water allocations this year because of drought. That resulted in production losses the state Department of Agriculture has estimated in excess of $1 billion in tree fruit, hay, hops, grapes, corn silage, berries and other crops.