On a sunny day in late April, the U.S. Army Corps of Engineers released hundreds of millions of gallons of water from Idaho’s Lucky Peak Dam, a dozen miles upstream of Boise. The dam operators call it a “rooster tail” display; thousands of observers took in the spectacle. The water, roaring out of a dam gate, arced high above the Boise River, rainbows shimmering in its spray.
Rooster tails are one way the Corps releases excess water to reduce the risk of flooding — a partially empty reservoir can capture spring runoff before it can race downstream and inundate Boise. Releases are necessary about seven years out of every 10, including this year, when basin flows were among the highest recorded. Lucky Peak and two associated reservoirs also store water for irrigation. In snow-heavy years, that means dam operators must strike a balance between letting enough water go early in the spring and retaining sufficient water for the hot, dry days to come.
Getting releases right is crucial for the farmers who depend on the Boise River to irrigate crops like sugar beets and seed corn. The river also waters lawns and parks, and supplies about 30 percent of Boise’s drinking water. As in other Western states, water users with older rights get first dibs. But since 2013, several irrigation companies and the Idaho Department of Water Resources have been fighting over administrative details that determine which water Lucky Peak irrigators are entitled to use during a wet year: flood-control releases, or the “refill” water that collects after releases…
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