WILLIAMS BAY — The Geneva Lake Environmental Agency is planning an underwater examination to determine how badly the lake is infested with starry stonewort.

At an emergency meeting Aug. 8, leaders of the environmental agency said they will send an expert to probe the bottom of Geneva Lake using a remote-controlled vehicle equipped with a camera.

The underwater mission was scheduled for Aug. 13.

Ted Peters, director of the Williams Bay-based agency, said going underwater to look at the plants is the only way to verify how large and widespread they are.

Starry stonewort is an unwanted invasive species that can grow into thick bushes and disrupt a lake’s boating, fishing and other recreational activities. It was first discovered last year in an isolated lagoon on Geneva Lake.

About 25 people attended the emergency meeting of the Geneva Lake Environmental Agency board of directors, which was called after reports that starry stonewort had been found in two new locations of the lake, signaling that it might be spreading.

Peters told the board that a professor from Aurora University near Chicago would conduct the underwater survey using a remote-controlled vehicle equipped with a camera. The professor also is a diver who will go underwater with the vehicle.

Depending on the what the survey shows, local efforts aimed at combating starry stonewort could turn from dredging the isolated lagoon to more widespread chemical treatments and boat cleaning programs.

“We may want to reassess what we want to do,” Peters said.

The agency’s board is scheduled to reconvene Aug. 15 to consider how to deal with the starry stonewort invasion.

After starry stonewort was found in Trinke Lagoon in the town of Linn, officials announced plans to dredge the lagoon in an attempt to eradicate the plant. That effort was later postponed when a dredging contractor said it would cost $800,000 — much more than expected.

The dredging plan was based on a hope that only the isolated lagoon was infested.

The invasive plant has since been reported found in two other areas of Geneva Lake, outside the Trinke Lagoon.

The new findings may result in the agency board deciding to devote resources to controlling with plant with chemical applications or other strategies, and establishing boat cleaning stations to ensure that no more invasive species get into the lake.

Several board members expressed support for prevention rather than dredging.

The two new areas with starry stonewort have been reported as a half mile east of Trinke Lagoon in 14 feet of water and just outside the lagoon entrance about 10 feet down.

Leaders of the Trinke lagoon area neighborhood in the town of Linn are still voicing support for lagoon dredging.

“Doing something is better than doing nothing,” said Stacey Cavanagh, a homeowner in Trinke Estates. “Time is of the essence. Let’s go get it where it is.”

Her husband, Ted Cavanagh, president of the homeowners association, said residents still support dredging.

“Now that the situation is worse, it seems like we’re falling away,” Ted Cavanagh said of the dredging plan. “We would like to see it done.”

Peters said he would recommend against the dredging.

Starry stonewort is a complex algae that can grow in thick mats, crowding out native plants and creating zones where fish and other aquatic animals cannot survive.

The plant has been found in 16 southeastern Wisconsin lakes and rivers, but never before in Walworth County.

Peters said that so far no one has been able to completely eradicate the plant from any lake. The best that anyone has done is control the plant by either using chemicals, smothering underwater blankets, or uprooting the plants with underwater vacuums.

All of those processes are expensive.

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.