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

Apr 9, 2014


A view of the lowered Columbia River at Crescent Bar near Vantage, Wash.
Credit Grant County PUD

Grant County officials said Wednesday they won’t nail down the cause of the crack on Wanapum Dam until June. It all means water levels on the Columbia River will stay lowered. That leaves boat launches, resort communities and popular parks high and dry. And as Correspondent Anna King reports, new details show the cause of the crack won’t be a simple fix.

So far, it’s not looking like a little tweak. Here’s what we know now: the 65-foot fracture wasn’t caused by seismic activity, a bad foundation or a shifting riverbed. And Army exercises at the nearby Yakima Training Center didn’t cause it either. Finally, the dam’s spillway gates were operated properly.

Thomas Stredwick is with the utility district. He 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,” said Stredwick.

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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