Mud flats have emerged at Mirror Pond, the result of a drawdown of the dam at the north end of the pond to repair a leak.
Engineers with PacifiCorp, the company that operates the more than 100-year-old dam, discovered the leak earlier this week, according to Bob Gravely, a company spokesman.
Gravely said the leak appears to be far less significant than the one that emerged in late 2013, when a hole in the dam dropped water levels in the pond 2 feet.
The leak discovered this week is not large enough to lower water levels on its own, Gravely said. Instead, PacifiCorp let out water through the bottom of the dam, allowing its crews to safely approach and repair the hole.
The new hole is in an overflow gate between the timber portion of the dam and a concrete section. Gravely said the gate is designed to be opened to free ice, logs or other debris that periodically will get snagged behind the dam.
Gravely said the hole in the gate should not cause damage to other parts of the dam, but the water it is letting through is flooding a small lawn adjacent to the powerhouse. He said initial estimates suggest water levels behind the dam will remain about 4 feet lower than normal for the next two weeks while repairs are completed.
Mud flats are likely to be a common site at Mirror Pond for the next few months because the Bend Park & Recreation District has requested PacifiCorp lower the water level behind the dam for eight weeks starting in late November. The district intends to make adjustments and changes at the whitewater park to improve the experience for floaters, paddlers and river surfers; representatives of the district have said it will be easier to conduct in-water construction if the river level is dropped.
Gravely said PacifiCorp decided it was better to tackle its dam repairs now than to wait a month for the drawdown requested by the park district.
Separately, the park district board will be meeting Tuesday to consider awarding a design contract to come up with a plan and cost estimates for reshaping the banks of Mirror Pond.
The bank realignment and restoration project is one part of a longer-term plan that could involve dredging accumulated sediment from the floor of Mirror Pond. The slowing of the river behind the dam contributes to sediment accumulation, and as the pond gets shallower, water temperatures rise, allowing for the proliferation of aquatic plants and making the pond less hospitable to native wildlife.
Earlier discussions included the possibility that the dam could be brought under local ownership, or removed or replaced with a different structure that would allow for a freer-flowing river. The park district has elected to push ahead with exploring the bank realignment, as it could go forward regardless of who owns the dam, or the plans of the private parties who have purchased the land beneath the pond.
Gravely said since the completion of the repairs following the 2013 hole found in the dam, PacifiCorp has had no plans to sell or dismantle the dam, but remains open to offers.
“Now that we’ve made the fix and it’s operating, we are willing to continue operating it in to the indefinite future,” he said. “We don’t have specific plans, the hope remains that there will be an outcome that works for everyone, but now that we’ve made the fix there’s no sense of urgency on our part.”
— Reporter: 541-383-0387,