​Wanapum Dam May Break Near Columbia River​​

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March 3, 2021

Wanapum Dam worries local residents of possible breakage. A major dam poses a risk of failure in the Columbia River that Grant County authorities in Wanapum have activated an emergency-response plan. Wanapum Dam is no threat to the public, with a crack that is just down stream from where Interstate 90 crosses the river.

However, utility managers are lowering water levels a total of 20 feet because they fear the structure otherwise could endanger inspectors trying to get a better handle on how seriously the damage is.

Local Utility working to fix dam:

“At this point we already know there’s a serious problem,” said Thomas Stredwick, spokesman for the Grant County Public Utility District (PUD) about the Wanapum Dam. “We want to make sure the spillway is stable enough that inspectors are safe when inspecting it.”

Earlier this week, an engineer noticed a slight irregular “bowing” above the spillway gates near where cars can drive across the Wanapum Dam.

Analyzing the dam’s spillway:

When divers finally took a look under water they found a 2-inch-wide crack that stretched for 65 feet along the base of one of the dam’s spillway piers.

After analyzing the data gathered by the divers and plugging it into computer models, the PUD determined late Friday afternoon that the failure risk was high enough that they needed to officially start notifying other government agencies and downstream water users.

“This is a situation that’s really changing as more information becomes available,” Stredwick said. “But there’s no immediate threat to public safety.”

Wanapum, just below The Gorge Amphitheatre and the hamlet of Vantage, is in a rural area. Failure would primarily impact fisherman, orchardists, farmers, boaters — and, of course, power generation. Wanapum dam currently can generate more than 1,000 megawatts of power.

What have officials done for the dam?

PUD officials have lowered the water 6 feet behind the dam since discovering the problem earlier in the week, leaving many boat ramps above the dam inaccessible.

  • Wanapum Dam Authorities plan to let water levels drop another 14 feet by Monday.
  • So far the PUD has been able to continue meeting all of its power needs, but Wanapum is such a big electricity generator the utility may ultimately have to turn to buying power on the open market.
  • Even if the Wanapum dam doesn’t fail, the significance of the damage is likely to require extensive repairs and that, too, could impact the entire Columbia River system.

“All these dams coordinate to generate energy on a regional scope,” Stedwick said. “If Wanapum is impacted, that has impacts on dams up stream as well as below.”

Kevin Wingert, a BPA spokesman, said the immediate impact would be an increase in flow from Priest Rapids Dam downstream, which would temporarily exceed the low flows needed to protect chinook salmon redds (nesting holes) through the Hanford Reach area.

He expected flows to return to normal once the drawdown was completed.

Where is the Wanapum Dam?

It is located on the Columbia River, six miles downstream of Vantage, Wash., 18 miles upstream of Priest Rapids Dam and 415 miles above the mouth of the river.

The dam was named Wanapum in honor of the band of Native Americans who live along a stretch of the Columbia River from Vantage south toward Pasco, Wash.

Wanapum Dam was financed by long-term revenue bonds that were retired through the sale of power. No tax money or government appropriations were used for construction of Priest Rapids or Wanapum dams.