Emergency Fish Passage at a Fractured Mainstem Columbia River Dam

Wanapum Dam was one of the largest dams built with this type of design. Photo credit: Todd N. Pearsons.

Wanapum Dam was one of the largest dams built with this type of design. Photo credit: Todd N. Pearsons.

Authors: Todd N. Pearsons, Thomas J. Dresser, Peter J. Graf, Michael S. Nicholls, Shannon Lowry, Michael C. Clement, and Curtis L. Dotson

On February 24, 2014, a hydro mechanic from Grant County Public Utility District (PUD) discovered an anomaly in the handrail and track on the deck of Wanapum Dam, a structure that spans the 2.6-km-wide Columbia River near Beverly, Washington. After alerting others and after further investigation, a 19.8-m-long, 5.1-cm-wide horizontal fracture causing an uplift and forward tilt of the dam was discovered. Grant County PUD immediately went into emergency mode and lowered the Wanapum Reservoir by 7.9 m to reduce the pressure against the massive concrete spillway, one of the largest spillway gate designs of its time (Photo).

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