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Idaho Matters

A plan to raise Anderson Ranch Dam

Officials want to raise Anderson Ranch Dam to provide more water storage to the Boise Basin.

Broadcast on:
15 Jun 2023

A large body of water sits in front of an earthen dam with large sloping plateaus on either side.
In May, #CPNRegion engineers briefed representatives from the Idaho Department of Water Resources, U.S. Forest Service, Idaho Transportation Department - Division of Aeronautics, and Idaho Power on multiple engineering projects related to the Anderson Ranch Dam Raise project. (Marc Ayalin / Bureau of Reclamation)

Officials want to raise Anderson Ranch Dam by six feet to provide more room for water storage in the reservoir.

The dam, which was online by 1951, sits on the south fork of the Boise River and provides power, irrigation water and flood control.

It’s one of three dams in the Boise River Basin that stores water as it melts and flows from higher elevations. During a spring like this one too much water melts at once, filling the dams and forcing officials to release large amounts of water downstream to avoid flooding. As of today, the three dams are 97 percent full and Anderson Ranch is at 98 percent of its capacity.

If Anderson Ranch is raised it would add 29,000-acre feet of storage space which could be a boon to irrigators and fish, and it would fill a growing demand for more water.

But raising a dam isn’t easy and could affect boaters and campers and the cost of the project recently jumped up by as much as $40 million.

So how do you raise a dam? To answer that question, we asked Cynthia Bridge Clark, the Water Projects Section Manager at the Idaho Department of Water Resources, and Lanie Paquin, Area Manager for the Bureau of Reclamation’s Snake River Office to join Idaho Matters.