WORTHINGTON — Renovations to the Lake Ocheda dam south of Worthington wrapped up Dec. 17, and with none of the stop logs in place, water levels in the three-basin lake continue to recede as part of a wintertime drawdown effort.
The long-discussed drawdown is one of the easiest and cheapest ways to address water quality in the lake, which has been on the state’s impaired waters list since 2010. Rough fish levels in the lake — particularly carp — have destroyed aquatic vegetation, which in turn has had a negative impact on water clarity.
“Water is flowing out as quickly as it can,” shared Okabena-Ocheda Watershed District Administrator Dan Livdahl on Friday. “The stop logs will probably stay out ’til March or April … and one way or another, we’ll put the stop logs back in in the spring.”
The lake should recover to its full service level for any recreation activity next summer, he added.
Livdahl said water levels in Lake Ocheda can drop another 18 inches through gravity. Within three days of the reopening of the dam last week, the lake level had dropped four inches.
“We kind of expected it to start dropping fast and then the rate will start slowing down,” said Livdahl, noting that the narrow channels at the bridges under Nobles County 5 and 57 are being monitored.
“What we’re hoping is the water flows fast enough to scour out a channel to get to that 2-feet drawdown,” he said. “This is our first opportunity to see if that will happen or not.”
While Livdahl said he wasn’t particularly optimistic about the success of a drawdown this winter due to water depths, there’s still a lot of winter weather ahead.
“We need low water conditions so we can get enough ice to freeze to the bottom,” he said, noting that during more recent drought years, higher levels of oxygen in the water helped rough fish survive.
During past winters with low water levels, there have been partial fish kills in the lake.
“Nature is going to do what nature is going to do,” Livdahl said. “We’re hoping that lowering the lake level by 2 feet will occasionally cause that fish kill that we need to have to manage the carp population.”
While the renovations to the dam are now allowing water to flow freely, the new fish screens are still being manufactured and will be installed later this winter. The screens will keep rough fish from reentering Lake Ocheda from the Ocheyedan River and nearby Peterson Slough.