Rain brightens SE Idaho irrigation picture

Craig Reed/For the Capital PressThree weeks of above average rainfall in the Snake River drainage in southeastern Idaho provided much needed water and helped Palisades Reservoir return to a nearly full level by mid-June. Water from the reservoir helps irrigate about 750,000 acres.

PALISADES, Idaho — Rains in May temporarily put a stop to worsening drought conditions in the Snake River drainage in southeastern Idaho.

The precipitation that fell in that month ranged from 160 to 200 percent of average, depending on the area, according to Mike Beus, the water operations manager in the Upper Snake River field office of the Bureau of Reclamation. He said there were some areas on the Snake plain that received “an extraordinary 3 inches a day.”

“It was especially wet on the south side of the Snake River plain and that’s where the irrigation takes place,” he said.

A dry spell in February had put the system well behind in storing water.

But the late spring rains lessened the demand for stored water for irrigation, demands that had come one to three weeks earlier than normal (early to mid-April). With demand down, Jackson Lake, Palisades Reservoir and American Falls Reservoir were able to reload and as of mid-June, the entire system was 89 percent full. Beus said Jackson was 98 percent full on June 15, Palisades was 99.7 percent full and American Falls was 77 percent full.

Beus said most of the Snake drainage’s Snowtel sites had no snow as of mid-May so the rain was much-needed.

“We were looking at a big hole left in the reservoirs and then three weeks of rain in May have given us a pretty adequate supply of water,” said Brian Olmstead, manager of Twin Falls Canal Co., the largest of the canal companies in Idaho. It has 120 miles of main canals and 1,000 miles of delivery laterals.

“Everybody is now starting out with full storage rights,” he said.

Southeastern Idaho producers are feeling fortunate because most other areas in their state, Washington, Oregon and California are suffering drought conditions and agricultural water users have already been cut off or reduced.

Beus said this year for the Snake drainage has been the opposite of last year, when there was a big snowpack, but then a dry spring. In July last year there was concern about having enough water to get through the season, but then rain fell in August, giving the reservoir system a good carryover for the 2015 season. Late summer crops, however, did get rained on.

“Sometimes you just have to hold your breath and hope for the best,” Olmstead said.

The Palisades Reservoir saves about 1.3 million acre-feet of water through the winter for use during the growing season on about 750,000 acres of irrigated land. Grain, alfalfa, pasture and a variety of vegetables and seeds depend on the water. The annual value of those irrigated crops is about $575 million and the annual value of the livestock industry is $314 million, making the water an important asset.

The Palisades Project was constructed during the 1950s to deal with possible drought conditions.

Twin Falls Canal Co. delivers water to 200,000 acres. Olmstead said if there is a shortage later in the summer, it would probably be alfalfa that would be shorted.

Beus said he expects hay growers in the upper Snake area to have enough water to get three cuttings and growers in the lower area to have four cuttings.

Beus said while it had been anticipated the reservoirs would be drawn drastically down, now it looks like at the end of the summer Jackson Lake will be half full, Palisades Reservoir will be 10-15 percent full and American Falls 8 to 10 percent full.

“That would be a little less than normal, but not a drought situation,” he said.

While the May rains were much needed and well received, they did ruin or lessen the quality of the first hay cutting.

“Sometimes that’s just how it happens,” Olmstead said. “But we’re a whole lot better off than a month ago. I think we’re going to make it through.”

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