IDAHO ON YOUR SIDE CHANNEL6 7-30-15 Arrowrock Dam

Jul 30, 2015

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Corps of Engineers looks to build on Arrowrock Dam for future water storage

By Jake Melder. CREATED Jul 30, 2015

With the surging population across the Valley comes growing pains, and government agencies are going toe to toe with conservationists over one of our desert community’s most important resources: water.

Two worries plague local and state leaders when it comes to population growth and water resources - storing enough water to avoid running out, and protecting infrastructure from potential floods. The army corps of engineers is looking to Arrowrock Dam to help solve the problem.

"We're looking for solutions that will satisfy both reducing flood risk in the valley and providing water supply," said Cindy Boen, Project Manager of the Boise River Feasibility Study.

That study indicated the need for an additional 80 to 170-thousand foot acres of water for development. The Army Corps suggests by raising Arrowrock Dam an additional 74 feet, the reservoir capacity would double totaling 250,000 acre feet.

The Idaho Conservation League says it's an inadequate solution.

"That's not really addressing the fact that we would be better suited to better implement water conservation measures to address an uncertain water future than to rely or count on water that may or may not show up behind a reservoir," said Marie Kellner, who works for ICL.

The ICL contends relatively cheap measures could conserve what water we already get. Reducing run-off and seepage from farming irrigation is their main target.

"If we could reduce just four percent of the loss that happens through [irrigation] we could come up with 174,000 acre feet of water a year," said Kellner.

But adding to Arrowrock also provides a safety net for unexpected flows. In the rare event of a devastating flood $10 billion of infrastructure would be in the flood zone.

"The cities in the Boise valley have been well-protected so far,” said Boen. “It's really just a matter of time before there's a really significant flood in that valley."

The feasibility plan includes a handful of other options - upgrading bridges and irrigation head gates as well as building diversion flood plains. The Corps will release an initial plan for public comment next spring.