WILLIAMS BAY — Trinke Lagoon will not be dredged this fall to combat the invasive plant starry stonewort, in part because the invasive plant species has been reported elsewhere in the lake.
The Geneva Lake Environmental Agency board of directors on Aug. 29 tabled the dredging option at a special meeting to consider options against the unwanted invader.
Agency director Ted Peters told board members now that starry stonewort has been reported in other areas of Geneva Lake, dredging isolated spots in the town of Linn’s Trinke Lagoon would be “a waste of resources.”
Dredging was first proposed when officials thought Trinke Lagoon was the only site of infestation.
“I thought we had a chance to eradicate it if it was in the lagoon,” Peters said. “We lost that chance. I’m sorry.”
First located in the Trinke Lagoon last year, starry stonewort is an unwanted algae that can spread and grow into thick bushes disrupting a lake’s fishing, boating and other recreational uses.
It has never been eradicated from any lake, and it has never been discovered anywhere in Walworth County until now.
Instead of dredging, the Williams Bay-based Geneva Lake Envionrnmental Agency will consider chemical applications to control the underwater plant species, following a planned Sept. 11 on-site review by the state Department of Natural Resources.
The action also sets aside the agency’s earlier plan to borrow up to $300,000 to pay for a combination of dredging and chemical treatments in the lagoon.
The purpose of dredging, which would be an expensive proposition, would have been to uproot and remove the plant’s only known area of infestation, thereby preventing it from spreading elsewhere in the lake.
Dredging cost projections had ranged from $174,000 to $800,000.
But since it was first discovered in Trinke Lagoon in October 2018, starry stonewort has been reported in two other parts of the lake — just outside the lagoon and also about a half mile east of the lagoon.
A more recent survey seemed to show that the plant had spread and may be even thriving in the lagoon.
On Aug. 13, the environmental agency sent a diver and a remote-controlled submersible robot into the lake looking for starry stonewort at locations where it had been detected.
The plant was found in abundance in the lagoon, but poor visibility in the lake made it difficult to find the invasive elsewhere, Peters said. That search was inconclusive.
The areas where the plant is growing in the lagoon had been chemically treated in June. A check earlier this summer indicated that the starry stonewort in the lagoon was not doing well.
The cost of using chemicals to try to control the starry stonewort is about $27,000.
The four board members present at the Aug. 29 special meeting were Pat Kenny of Fontana, Doug Skates of Lake Geneva, Roy White of town of Linn and LaMarr “Sparky” Lundberg of Williams Bay.
Jen McMannamy of Williams Bay was absent.
Not everyone at the meeting was ready to give up on dredging, however.
Tim Cavanagh, president of the Trinke Estates Property Owners Association. said his group still supports dredging the lagoon and is willing to help with such an effort.
“We are willing to provide access, support, whatever you need,” Cavanagh said.
Later, Cavanagh said homeowners support the most aggressive method to combat starry stonewort. That would include removing their boats from the lagoon and providing access to Trinke property.
Peters said Geneva Lake is only one of 12 lakes in Wisconsin invaded by starry stonewort.
“We’re still learning about it,” he said.
Most of the data that Wisconsin uses to deal with starry stonewort comes from Minnesota, Michigan and New York, where starry stonewort appeared earlier.
“Every report I’ve read said dredging doesn’t work,” Peters said.
He added that no process, from hand-pulling by divers to dredging to chemical treatments, has been successful in eradicating the plant anywhere in North America.
If there is a bright side, he said, the starry stonewort is not expanding quickly where it is surrounded by native plants. Instead, the weed tends to grow more quicker and thicker on bare spots on the lake floor.
A key to containing starry stonewort appears to be maintaining a healthy diversity of plants on the lake bottom, Peters said.
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