PacifiCorp pulled the drain plug on Mirror Pond early Monday, opening up the sluice gates on the Newport Avenue Dam to allow for the inspection of a recently discovered leak.
Bob Gravely, spokesman for PacifiCorp, said the utility plans to lower the pond on the Deschutes River at a rate of 2 inches per hour for two to three days until the water has dropped enough for inspectors to approach the dam safely.
“I was told it could be pretty low, even lower than anyone in town has ever seen it,” he said.
Gravely said the inspection itself is expected to take around eight hours. No repairs will be performed this week. Once the inspection is complete, PacifiCorp will close the sluice gates, and the pond will return to the roughly two feet-below-normal level it’s been at since the leak was discovered early this month.
“There’s no fix planned; this is the assessment that will inform all of our decisions going forward, that’s both the fix, and the long-term plans for the dam,” Gravely said.
Engineers from the Oregon Water Resources Department will also inspect the dam while water is low this week.
Bend City Councilor Mark Capell said PacifiCorp and the state will separately produce reports on the viability of the dam.
“We expect to know something in six weeks,” Capell said.
Kyle Gorman, south central region manager with the Oregon Water Resources Department, said Monday that the state normally inspects this dam once every three years, with its last inspection in July 2012.
“But, given the opportunity with the water level being very low and some other coordinated efforts, we thought it would be good to get out there and inspect,” Gorman said.
Gravely said the PacifiCorp inspection will be conducted on the downstream side of the dam, once the water is low enough that it is no longer flowing through the hole in the dam. Inspectors will examine all 13 wooden “bays” visible from the Newport Avenue Bridge, he said, as well as the concrete portion of the dam between the wooden dam and the powerhouse.
Mirror Pond Project Manager Jim Figurski said city and parks officials have not yet scheduled the next meeting of the Mirror Pond ad hoc committee. The committee was formed by Bend City Council and the Bend Park & Recreation District to refine a final plan for the future of the landmark body of water in the heart of Bend.
In the meantime, Figurski plans to take advantage of the lower water level to take more photographs of the pond.
“I’ll probably get more photos,” Figurski said. “I’d like to get it as low as possible, because I think it helps people visualize.”
On Friday, a subcommittee that consists of Capell, park district Executive Director Don Horton and park district lawyer Neil Bryant met privately with the utility.
“Basically, we wanted to know what Pacific Power wanted to do with the dam,” Capell said. “We basically said we’d like to know what your plans are. At this point, they want to wait until they see the results of the studies and at that point, they’ll be able to look at the economics of the dam and figure out the best long-term approach.”
Capell said he did not know when he and Horton and Bryant will next meet with PacifiCorp executives.
Gravely said the utility will keep the public informed about the results of the dam inspection this week, though the utility may not share all of its findings.
Over the last five years, three leaks have been repaired in the wooden portion of the dam. While the newest leak appears to be similar, the more-than 100-year-old dam is nearing the end of its useful life as a power generation facility. In order to maintain water levels, the dam’s hydroelectric turbines have been turned off since the discovery of the hole.
This week’s inspection should help determine whether PacifiCorp can feasibly repair and continue operating the dam, Gravely said. If not, the utility would have the choice of transferring ownership to another entity that would continue running it, or dismantling the structure, effectively draining Mirror Pond permanently.
“I think there’s this impression you can just go down and nail up some plywood, and it’s a little more involved than that,” Gravely said.