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For the week of April 11 through April 17, 2001

Drought to hit irrigators

Water rights priorities set below Magic Reservoir

Express Staff Writer

The outlook for a low water year and rising power costs is casting a long shadow over Idaho’s approaching summer.

Though scenic, water trickling down Trail Creek, through Sun Valley and Ketchum, will probably do little to help downstream irrigators in the summer to come. Express photo by Willy Cook

With mountain snowpacks as low as they’ve been in decades, the water forecast is dismal, and Idaho Power Co. has asked for a $227 million rate increase to cover—among other things—the projected shortfall at its hydropower generating dams.

But just how bad it will be could depend on location and weather over the next six to eight weeks. The forecast is for a wet spell in the near future, but the longer term remains uncertain, according to the National Weather Service in Pocatello.

In some places, rain will only delay the inevitable.

The Big and Little Wood basins hold about 45 percent of their average snowpacks. Further, the state water master for the local water district, Lee Peterson, said he believes spring runoff on the Big Wood River has already peaked.

"It does not look very promising," he said. "There’s a very good chance we have peaked out already. If we should get some real warm rains up there, then we would get a gush coming down."

Peterson said he believes most of the snowmelt is seeping into the ground rather than into area streams and rivers.

The Big Wood Irrigation Co. expects to start delivery of water stored in Magic Reservoir, primarily filled from the Big Wood, around May 1 or, if wet spring conditions persist, shortly thereafter. The reservoir now holds only 70,000 acre feet of water, which is about 35 or 36 percent of its capacity.

That’s enough to supply 30 to 45 days of water to irrigators, canal company manger Lynn Harmon said.

By mid-June there should be only 4,500 to 6,000 acre-feet left in Magic, he said.

"It looks pretty sad when it gets down to that," Harmon said.

The canal company has not asked irrigators not to plant crops, he said, but to plant crops that consume less water. That means more oats and barley instead of sugar beets and potatoes, and only one or two cuttings of alfalfa.

Other small reservoirs face similar dismal circumstances. The snowpack in the Salmon Falls basin, south of Twin Falls, is at about 71 percent of average, and in the Oakley Reservoir Basin it is 50 percent.

For larger, reservoir-serviced irrigation tracts, the picture is a little better.

Jackson Lake, on the Snake River in Wyoming, is nearly full, but Palisades Reservoir, upstream of Idaho Falls, is not likely to fill. Downstream, the American Falls Reservoir is the only one on the Snake that‘s full.

Those three reservoirs provide the bulk of irrigation storage for Magic Valley irrigators.

If the spring remains cool and damp, which would delay the start of irrigation demand, the stored water will last longer. But inevitably, some irrigators will not receive enough water this year.

The state distributes water based on seniority, a concept called "first in time, first in right." Canal companies are on the delivering end of the equation.

The Idaho Department of Water Resources has established priority cuts for Big Wood, Little Wood and Silver Creek basins, dating as far back as June 1885 for Little Wood irrigators. The oldest right on the Little Wood is April 1877.

The priority cuts for the Big Wood River above Magic Reservoir are not yet in, but below Magic on the Big Wood, they are set at April 1905.

The oldest water right on the Big Wood below Magic is April 1882.

The Twin Falls Canal Co., which relies primarily on natural flows, expects to begin the season delivering three fourths of a miner’s inch per acre. One cubic foot per second of water equals 50 miner’s inches.

The expected low water levels will affect more than irrigators.

Idaho Department of Fish and Game officials say low water in reservoirs will affect fisheries, possible wiping some out. Spokesman Mike Todd said officials are particularly concerned about Magic, Mormon and Fish Creek reservoirs.

As the reservoirs go dry, fishing limits may be lifted to allow salvage fishing. Already the limits have been lifted on the Big Wood River below Magic Reservoir.



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