Meeting with Cologne City Council, a member of the Benton Lake Conservancy proposed moving forward with plans to clean the lake that has become the centerpiece of the city.
The plan aims to reduce pollution as well as trim the invasive carp population that has overtaken the biomass of the lake.
“Benton Lake is the most polluted lake in the seven-county metropolitan area,” Don Smith, of Benton Lake Conservancy, said.
The proposal involves the introduction of predatory fish. This would include the reintroduction of perch, bass and sunfish to keep carp populations in check. Smith noted that sunfish in particular are desirable.
“Sunfish are the biggest predator of carp eggs, they just love them,” Smith said.
Smith notes that the Carver County Water Management Organization recommends that to return Benton Lake to a healthy state, the carp population must be reduced to 10 fish per 1,000 square yards or eliminated entirely.
To support the new fish population, the group asked the city for its assistance in taking ownership of an aerator that would oxygenate the water, helping the predatory fish that are introduced survive.
“We think it will really work, and our goal is to get the lake cleaned up, and free of carp. Basically that’s the only way we’re going to be able to do it,” John Hendel, member of Benton Lake Conservancy, said.
The problems with the lake, according to Smith, are not limited to invasive fish. Smith said that currently there is approximately 15 feet of sludge in the lake, which is prohibiting survival of other plant and marine life. He told a story to the council regarding a six-inch clam he found dead, and what that showed him.
“For a clam to live that long, it had to be a good lake,” Smith said.
The city’s end in the proposed restoration would be assuming responsibility of maintenance for the aerator as well as contributing funds to repopulate the lake with predatory fish.
The compressor, described by Smith, is a single phase motor run off belts, and not very large. The only maintenance, he said, would be periodic oiling. With that, the motor could run 10 years, according to Smith. He went on to describe the aerator he proposed as having high appraisals from Lake County, who called it one of the best.
Problems acknowledged with the system involve the aeration tubes that would run through the lake. It was noted that other areas had experienced difficulty with boats anchors that could drift and pull on the tubes. This had been solved in other areas by adding six-inch well pipe to keep them grounded, Smith said.
When asked for a proposed timeline, the group was quick to respond with immediacy.
“I think it’s better to get the predator fish in there as soon as you can, because you’re not going to stay ahead of those carp, they’re going to keep multiplying ad multiplying, and you got to get something else in there to keep them in check,” Hendel said.
It was also noted that while there are currently sunfish in the lake, the population is too low to be effective.
Moving forward with the aerator and fish restocking would constitute phase 2 of the Benton Lake cleanup. Late last fall, the CCWMO, along with the independent contractor Carp Solutions, removed approximately 4,000 lbs. of carp from the lake in an effort to curb the population.
It was noted in the meeting that the estimated cost for these removals falls between $3,000 to $4,000.
It was acknowledged that the project will take time to see results. Water clarity is another issue that has had an impact on aquatic life, particularly vegetation, but reducing the carp population will aid in that.
“With an aerator there’s hope we can get this lake restored, hopefully having everybody’s kids, grandkids, fishing at a dock at some point,” Hendel said..