PacifiCorp has completed repairs to the Mirror Pond dam, a spokesman said Wednesday, and believes water levels in the pond should return to normal this summer.
The recent repairs were prompted by a leak in the dam that emerged in early October. Within days of the discovery of the leak — described as a basketball-sized hole below the normal waterline — Mirror Pond began dropping, exposing wide mudflats that extended through Drake Park and upstream of the Galveston Avenue Bridge.
PacifiCorp, the owner of the dam, inspected the damage and concluded the century-old dam was too damaged to warrant further repairs. In late November, the company announced it was ready to decommission it or transfer it to another entity.
In February, the utility reversed course and agreed to repair the dam.
Spokesman Bob Gravely said Wednesday that crews completed nearly all of their work Friday, driving large pieces of metal sheeting into the bedrock beneath the upstream side of the dam. Gravely said because the equipment and crews were available, PacifiCorp also added sheeting to another two of the 13 wood and rock “bays” that make up the spillway visible from the Newport Avenue Bridge.
During last fall’s inspection, the two bays added to the repair operation were found to be holding water but in danger of failing, Gravely said. Six of the 13 bays in the spillway have now been repaired using the same technique in recent years. Gravely said discussions between PacifiCorp and the Bend Park & Recreation District about the district’s possible acquisition of the dam have been temporarily suspended until the district’s inspection report is complete.
“On hold would be the wrong word, but once the Parks Department decided to do its own inspection, I think both sides agreed it would make sense to wait until both sides had their own sets of numbers and projections before continuing the talks,” he said.
Gravely said PacifiCorp repaired the dam even though officials believe the new leak was allowing too little water through to affect the level of the pond once the Deschutes River returns to full summer flows. Water running through smaller leaks in the dam tends to displace the timbers and rock inside, he said, creating larger leaks if not repaired.
“Anything I guess could still happen, but this will significantly increase the likelihood that the dam will maintain the water levels for the foreseeable future,” he said.
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