SPOKANE — The crack in a spillway pier at the Wanapum Dam has been downgraded to a “non-failure emergency,” meaning the pier is no longer considered at risk of collapsing, the Grant County Public Utility District said Wednesday.
The downgrade is the result of engineering surveys conducted Monday and Tuesday that show the fractured area found on one of the dam’s spillways was continuing to stabilize, the PUD said in a press release.
“This is still a serious issue,” Chuck Allen, a public affairs officer for the PUD, said Wednesday.
As of 6 p.m. Tuesday, surveys showed that the impacted area was stable, the PUD said.
The dam is located a few miles south of Vantage on the Columbia River.
The crack has closed and a section of the spillway pier that had shifted has nearly returned to full alignment, the PUD said. That’s the result of the utility lowering the water level by 26 feet in the reservoir behind the dam, reducing pressure on the damaged spillway, the PUD said.
The 65-foot long crack was discovered last Thursday, and the dam had operated under the status of a “developing failure,” since last Friday, the PUD said.
Officials are still trying to determine what caused the crack and have not developed a plan for repairing the damage, Allen said.
The reservoir level will remain at 26 feet below normal for the foreseeable future, Allen said.
As a result, the dam is generating electricity at about half of its total capacity of 700 megawatts, he said. But it continues to meet customer electricity demands at the reduced level, the PUD said.
The 2-inch-wide underwater crack extends horizontally across the upstream side of the 65-foot wide pier. It’s one of 12 piers on the spillway.
A spillway is the portion of the dam that allows water to “spill” past the dam as opposed to running through the turbines.
The reduced water level behind the dam means that all boat launches on the Priest Rapids and Wanapum reservoirs remain closed. The Wanapum Heritage Center and the day-use park at Wanapum Dam are also closed, the PUD said.
Lowering the reservoir has exposed shoreline that had been covered with water since the dam filled 50 years ago, said Grant County PUD spokesman Tom Stredwick.
“It’s an opportunity to see something you wouldn’t normally see,” he said Tuesday.
The Yakima Herald-Republic reported that visitors were snapping photographs of the area on Tuesday, while others walked amid the rocks and sandbars. A family was exploring with a metal detector.
The banks of the Columbia are a rich source of tribal artifacts since Indians lived along the river and used it for travel for generations, said Allyson Brooks, the Washington state historic preservation officer.
She is concerned about looters digging into sites that were inundated, or amateur archaeologists looking for items such as stone tools.
“If they impacted a burial area, it would be a felony,” Brooks said Tuesday in Olympia.
The Grant County sheriff’s office announced Tuesday that what detectives believe are human bones had been found in an area newly uncovered by the drawdown of the dam.
The sheriff’s office said a person walking along the river at Crescent Bar on Tuesday afternoon found the bones.
Because it’s possible the bones are those of a Native American, leaders of the nearby Wanapum Tribe visited the scene. The sheriff’s office and Washington State Patrol Crime Lab plan to collect the remains for analysis.
