starry stonewort

The Geneva Lake Environmental Agency and the state Department of Natural Resources are battling starry stonewort, an invasive species of algae that could disrupt Geneva Lake.

WILLIAMS BAY — Chemical treatments have been applied and a lagoon has been temporarily closed in the battle to control a new invasive plant species on Geneva Lake.

The Geneva Lake Environmental Agency reports that a contractor applied chemical treatments June 18 to combat starry stonewort in the lagoon by the Trinke Estates neighborhood in the town of Linn.

Starry stonewort is an invasive algae that can spread and disrupt boating, fishing and other recreational activities on a lake. It was discovered recently in the Trinke lagoon, and efforts are underway to keep it from spreading elsewhere in Geneva Lake.

An earlier plan for dredging the lagoon was postponed because of high costs. The strategy now is controlling the starry stonewort with chemicals, and trying again for a dredging program in the fall.

After the chemical treatments were applied June 18, the lagoon was barricaded and was scheduled to remain closed for 10 days.

Ted Peters, director of the Williams Bay-based environmental agency, said state regulators would monitor the lagoon for 10 days to make sure that the chemicals were working and that the chemicals stay where they were applied.

The application of “algaecide” chemicals was performed by a private contractor with permission from the state Department of Natural Resources, and was paid for by the Geneva Lake Environmental Agency.

Peters estimated the cost at $5,000.

Leadership of the nearby Trinke Estates Homeowners Association voiced support for both the chemical applications and the temporary closure of their lagoon.

Tim Cavanagh, president of the Trinke Estates Homeowners Association, said some homeowners moved their boats out of the lagoon, while others were waiting for the lagoon to reopen.

“It is, of course, an inconvenience,” Cavanagh said. “But our 40 homeowners are committed to assisting GLEA and the DNR with eradicating starry stonewort.”

Peters said the chemicals should not have an adverse effect on other wildlife in the lagoon in the concentrations in which they were applied.

Jon Duggan, co-owner of contractor BioAquatics of Lake Geneva, said the two chemicals — Cutrine plus and Hydrothol — work specifically on algae. He said the Hydrothol was applied at 0.15 parts per million and the Cutrine was applied at 0.6 parts per million.

The amount of chemicals was strictly controlled by the DNR, officials said.

The concentrations of toxins was meant to kill the starry stonewort without harming surrounding plants, Peters said.

“If you kill all the plants in an area, you are opening the door for invasives,” he said. “But also the plants decompose, which uses up oxygen.”

A lack of oxygen would make it hard on the fish and animal life in the water, as well.

Peters said plastic barriers set up to contain the anti-algae chemicals were working.

A barrier separating the treated area from the rest of the lagoon appeared to have been cut, but Peters said it appeared that the barrier was still holding the chemical within the treated area.

The opening would allow the few fish still in the lagoon to move into the treated area. Peters said he believes that the fish will avoid the treated area, however.

The environmental agency will continue to monitor the lagoon and the barrier. It was uncertain whether the barrier needed to be repaired, he said.

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Chris Schultz has been a reporter for more than 40 years. He has been with the Lake Geneva Regional since 2010. He covers the Lake Geneva City Council and the Lake Geneva area schools.