Lake/Dam News from NE WI
Dunn County News
Draw down and out
By Joel Becker, Editor
On Friday, the draw down of Tainter Lake reached the five-and-a-half-foot mark. The level of the lake was taken down so that work can be done to the dam in Cedar Falls by Xcel Energy.
According to Rob Olson, hydro licensing specialist with Excel based in the Western Avenue Service Center in Eau Claire, the draw down went well.
He reported that earlier in the week he accompanied DNR officials to check on areas where fish may be stranded by the dropping level of the water. "We didn't find any problems at all," he said.
The lake was taken down in six-inch-per-day increments, which Olson said allowed fish to escape to deeper water.
While much of the lake and river area behind the dam just looked like there was much less water available, the area near Champney Park showed what people have known for years.
There is a large amount of sediment on the north end of the lake where the Red Cedar River feeds into the larger body of water.
Though Excel has nothing to do with the sediment, Olson's observation was, "You get a really good appreciation for the amount of sediment that has been delivered to that lake since 1910. God knows how many truckloads of sand you'd have to haul out of there to restore it."
At the dam, subcontractors have begun working to replace the old wood flashboards. During the next four to six weeks the level will be kept down and the concrete on the dam will be prepared for the new rubber system.
Olson said he believes the flashboard system was installed in the 1930s following a flood. He also said the flashboards allowed more energy to be generated, but during high-water events the flashboard would sometimes get washed out.
Once the water level went down, the flashboards would have to be replaced.
"We knew this project was upcoming and it was just a matter of time of getting the new license to where we could ahead and start the project," Olson said. "We've just gotten by with the basic essentials knowing we were going to replace them anyway."
He said the rubber system doesn't give any more spillway capacity, but the level of the lake will be able to be controlled better.
In the past, when the boards went out, Olson said there would be a four-foot draw down to replace the boards, which happened, on average, once a year. The repair and replacement of the boards cost about $10,000 per time.
"People have this idea that the flashboard didn't work very well," Olson said. "That's exactly how flashboards work. That's how they're designed. They're designed to fail and they're designed to fail to pass excess water that you can't pass any other way. They've actually been very effective for a lot of years. Now we're just going to a new system where we won't have the draw down anymore."
The cost of the project is $600,000.
If everything goes well, Olson estimates that by the end of October or the first part of November, the lake will be back up to its usual level.
However, heavy rains and increased flow in the river in the next four to six weeks could delay the project.
The lake will be refilled at a 60/40 rate.
Olson said 60 percent of the water that flows through the river will be passed downstream and 40 percent will be retained to fill the lake.
"We could fill it a lot quicker, but we don't want to cut off flow because eventually there's no water downstream," he said.
posted by Slide @ 10:40 AM
