Crack leads to potential failure at Vantage-area dam

BEVERLY, Wash. – Grant County PUD has alerted emergency officials, state agencies, other dam operators and downstream property owners that a potential failure situation is developing at Wanapum Dam.

PUD spokesman Tom Stredwick said the “Emergency Action Plan B” was declared at approximately 3 p.m. Friday. That level of alert means that a potential failure situation is developing, he said.

“Catastrophic failure is very unlikely,” PUD Assistant General Manager Chuck Berry said late Friday. “We’re generating now. We’re not anticipating a huge amount of water coming. In a worst-case scenario and that piece of the spillway would fail, the flows that would move into the river below would not exceed the regular flow of the Columbia River. There is plenty of room to handle it.”

PUD General Manager Tony Webb said it’s too soon to tell what caused the crack, but they’re investigating and focused on safety. “We have good people on it,” he said. “We’ve got the right mission: public safety and health and protection of the dam. We’re trying not to get distracted to see how we stabilize it, how to fix it and move on. I want my staff focused.”

The heightened alert at the dam comes after divers Thursday discovered a fissure in one of the dam’s concrete support piers that measures 2 inches wide by 65 feet long.

The PUD will draw down the reservoir to reduce pressure on the dam and help ensure the vulnerable area remains stable.

The fissure runs horizontally along the down-river face of the spillgate pier, Stredwick said. It’s about 75 feet below the water surface. It runs the entire width of the 65-foot-wide pier, which is 126 feet tall and 92 feet thick.

PUD officials have not said what could have caused the crack, Stredwick said.

Wanapum Dam is the PUD’s largest power plant, capable of generating 1,092 megawatts of electricity, enough to supply nearly 900,000 Northwest homes. It’s just south of Vantage where Interstate 90 crosses the Columbia River.