Dam leak adds twist to pond debate

Oct 05, 2013

Bend Bulletin

Dam leak adds twist to pond debate

Dam owner to inspect for other issues while Mirror Pond water level is low

By Scott Hammers

Water levels in Mirror Pond are expected to drop in the coming days, as PacifiCorp inspects a leak discovered in the Newport Avenue Dam.

Bob Gravely, spokesman for the utility company, said the leak is in one the 13 wooden “bays" visible from the Newport Avenue bridge. The company has previously repaired leaks in two other bays, he said, but the severity of the latest leak will not be apparent until water levels are lowered sufficiently to allow closer examination.

Water levels at the dam have already fallen approximately 21⁄2 inches due to the leak, Gravely said, and PacifiCorp has shut down its electrical generation turbine to maintain water levels upstream.

As of Friday evening, PacifiCorp was checking whether any permitting or regulatory obstacles prevent the company from dropping water levels to begin the work. The company has not yet determined how much water will have to be released, or how low water levels above the dam could drop.

The leak comes in the middle of a larger public process surrounding Mirror Pond, and what should be done to address silt that has accumulated on the floor of the pond in the 29 years since it was last dredged. In public meetings and online surveys conducted earlier in the year, community members were largely split. One faction supports dredging to maintain the pond, and another favors removing the dam to create something closer to a free-flowing river.

PacifiCorp has been involved in the discussions but has been noncommittal, other than to state the day will come when the dam is no longer economical to operate. In recent years, the dam has generated enough electricity to power 200-300 homes.

Gravely said that while the new leak does not appear to be significant, PacifiCorp intends a thorough inspection of the entire dam while water levels are lowered to look for any other emerging maintenance issues.

“It is 100 years old, and I think we've been saying we could be one repair away from this not being worth it to fix," he said.

Don Horton, director of the Bend Park & Recreation District, said he won't know until PacifiCorp has completed its work if the leak will change the discussion of what to do with Mirror Pond. Horton is one member of an ad-hoc committee that has been gathering information from PacifiCorp to report back to the Bend City Council and the park district board with a recommendation for Mirror Pond. He said the leak will, at minimum, give him and others involved in the process a preview of what a free-flowing river might look like.

“If it does come down, it's an opportunity for us to photograph what we see — it's not very often this happens — we may be able to learn something from it," he said.

Horton said he's curious to see if opening the sluice gates to lower water levels will actually flush out significant quantities of silt, though he added he's doubtful that will happen.

Spencer Dahl, a past member of the Mirror Pond Management Board, said he'd prefer to know what the undammed river looks like when flows are not already reduced on account of the end of irrigation season, but is still interested to see what areas dry up when the water levels drop.

During his time on the board, Dahl unsuccessfully tried to persuade PacifiCorp to drop water levels in order to show the public what the area might look like if the dam were removed.

Dahl said he suspects the announcement of the leak — Gravely said the leak was discovered Wednesday; Dahl said he's noticed the bay in question leaking for much longer — suggests PacifiCorp may be ready to take a firmer public position on their plans for the dam.

“I'm pretty sure its a move toward resolution of the Mirror Pond problem, whether it's them selling the dam or them trying to justify abandoning it," Dahl said. “I can't see any other reason for the timing, because that leak's been there for months, if not years."

Gravely said water levels during dam repairs could be further affected by activity at Wickiup Dam, where water managers have begun refilling the reservoir by cutting back on the water released into the Deschutes River. Within the last week, releases at Wickiup Dam have been reduced by more than half, according to figures compiled by the Bureau of Reclamation.

e_SEmD Reporter: 541-383-0387, shammers@bendbulletin.com

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