Sedimentation trap eyed by city officials

ANTIGO — Thursday night at an inland lake district meeting, city officials detailed a potential plan to construct a sedimentation trap north of Antigo Lake.

The sedimentation trap would divert runoff that until now has flowed from farm fields north of the city into the lake through Spring Brook into a pond that would be emptied annually to make Antigo Lake, in theory, far cleaner than at present.

“When we get the spring runoffs, I’m sure a lot of you folks have seen that, basically, that lake turns to chocolate milk,” said City of Antigo Director of Public Works Charley Brinkmeier. “So if we can trap soil sediments upstream, what we’re going for is to get the sediment there, have our trucks come in with a backhoe, and actually move the sediment every year at that location.”

“It’s a manmade structure…We’ve already had some preliminary talks with a couple of [DNR officials]...They think we can do this. It’s just a matter of making sure we dot every I and cross every T with every department.”

Construction on the sedimentation trap could take the better part of a year and would likely occur close to the footbridge on the Spring Brook Trail near Virginia St.

“That’s an area where we can get our trucks right in on the dead end of Virginia,” Brinkmeier said. “We have to make a little path in here, have a flat platform for an excavator to sit, and a dump truck obviously as they load the truck out…

Obviously, we’re not going to purchase land up in the farm fields to stop that. That’s just impractical. This is an area where we already own the property. The engineers that looked at it said, ‘Yes, it should work. We’ll be able to get a large amount of tonnage out of there of sentiment to help stop that from getting into the basins.’”

Officials characterized the sedimentation trap as a far more efficient way by which to maintain the lake’s clarity than dredging it, an alternative they said the city commissioned several years ago at the cost of $1 million for just one of the lake’s three basins.

“As a member and citizen of the City of Antigo, we value those basins, and I would hope at some point in the future they would become pristine where we could use them for recreation,” said Third Ward Alderman Tim Kassis, who is also the chairman of the inland lake district committee. “A lot of things could be done in those basins if we could clean them up. I think by moving the money from the dredging to the sedimentation, it puts us on a course to do that.”

In order to begin construction on the project, Brinkmeier said the city will first need to get past considerable red tape, including assessments regarding whether wildlife could be harmed due to the construction.

“There’s a lot of moving parts to this because of the different divisions of the DNR,” he said. “We have to meet with the fishery people to make sure they’re OK with it. The wetlands people, the floodplain people — there’s a myriad of people we have to meet with, as well as the Army Corps. It’s going to be well over a year before we would even know 100 percent if this is going to go…Ayres did the original study on that to see what kind of siltation we could probably capture in an area like that. So we have that information which is what the DNR is going to want.”

Officials hope the prospective project will make cleaning Antigo Lake a sustainable endeavor.

“The dredging is a large operation — very expensive, very time-consuming,” Brinkmeier said. “If this were to go forward like we’re envisioning it to do, this would be something we could do on an annual basis, and remove a large amount of sediment from ever getting into the basins at all.”