YAKIMA, Wash. — Yakima Basin irrigators finished their season with more water in their mountain reservoirs than in the past two years and a bonus of 15 to 20 inches of rain and snow last weekend.
The storm, starting Thursday, Oct. 19, and ending Sunday, Oct. 22, brought 15 inches of precipitation in the mountains feeding the basin and 20 inches of snow in the highest elevations, said Joe Gutierrez, assistant river operator of the Yakima system for the U.S. Bureau of Reclamation in Yakima.
“It was a good event. More than I expected. We’ve had larger in the past but this was the first of more to come we hope. It’s a good start for the water year,” Gutierrez said.
The Oct. 1-24 precipitation for the basin is 42.24 inches or 325 percent of average and 241 percent of the month’s average, he said.
It added 53,064 acre-feet of water to the basin’s five mountain reservoirs in five days, bringing the total to 361,077 acre-feet, which is 134 percent of average storage for this time of year.
Irrigation diversions ended Oct. 20 with the collective low point of the five reservoirs most likely reached three days earlier at 306,840 acre-feet, said Chris Lynch, the Bureau’s Yakima Basin hydrologist.
“That should be the low point unless we get dry after this rain,” he said.
The low was 244,500 acre-feet on Oct. 12 a year ago and 107,323 acre-feet two years ago following the 2015 drought. Average low over the past 30 years is 261,000 acre-feet.
Full pool of Keechelus, Kachess, Cle Elum, Rimrock and Bumping reservoirs is 1,065,400 acre-feet and is usually obtained before irrigation season begins in June.
The system serves 464,000 acres of mostly farmland along 175 miles of the 214-mile-long Yakima River in the Kittitas and Yakima valleys. It is among the state’s richest farmland abundant in tree fruit, hay, wine grapes, hops and many other crops, cattle and dairies.
The longterm outlook calls for a La Nina weather pattern which Lynch said usually is good news. It should mean normal to above average precipitation and temperatures on the cooler side, he said.
“It should mean a typical winter of normal snowpack and normal is good. But nature can always throw a curve ball. I’m hopeful we will be fine for the next irrigation season,” he said.
Yakima Basin irrigators depend on the reservoirs and need another 700,000 acre-feet out of 2.3 million acre-feet normally stored in mountain snowpack.