WILLIAMS BAY — The Geneva Lake Environmental Agency is planning a new underwater examination to get a clearer picture of infestation of the invasive plant starry stonewort.

At an emergency meeting Thursday night, 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 is 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 algae 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 Thursday night's 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.