What Cracked Wanapum Dam? Experts Won't Know Until June | KUOW News and Information

What Cracked Wanapum Dam? Experts Won't Know Until June

Apr 10, 2014
Originally published on April 9, 2014 5:25 pm

Central Washington could be in for a bummer of a summer as Grant County officials have said they won’t nail down the cause of the crack on Wanapum Dam until June.

That means water levels on the Columbia River will stay lowered, leaving boat launches, resort communities and popular parks high and dry.

New details show the cause of the crack won’t be a simple fix.

The 65-foot fracture wasn’t caused by seismic activity, a bad foundation or a shifting riverbed. Army exercises at the nearby Yakima Training Center didn’t cause it and the dam’s spillway gates were operated properly.

Thomas Stredwick of the Grant County PUD says that leaves the dam’s design or its original construction as the possible cause.

“It’s likely one or a combination of the materials that were used at the time of construction, or a design issue at the time of construction.”

Stredwick says tension from water pressure on the face of the spillway may have played a role in the crack. That’s a problem, because the dam should be designed to handle that pressure.

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