Toxic Scum Sours Swimming Fun on Conesus Lake

CONESUS – An unusually large patch of blue green algae floating on the North Shore of Conesus Lake has made many lakeside residents turn up their noses to the water for the past two weeks. According to the Livingston County Department of Health, who issued a public warning about the algae on August 19, the raft of tiny bluish-green plants is home to a special strain of bacteria that release toxins as the plants inevitably die.

The algae is a part of the lake’s normal ecosystem, Department of Environmental Health officials said, but cause problems when the right environmental factors make patches of it grow to abnormal size. Sunlight, temperature, wind disturbance, and nutrient quality all affect the size of annual algae patches.

“The wind is a day-to-day thing,” said Mark Grovanz, Director of the Environmental Health for the Health Department, “some days it’s windy and some days not. But fertilizers do get into the lake from runoff. Even grass clippings from lawns in the watershed can have enough fertilizer on them to affect the lake, and the watershed for Conesus is quite large.”

The Health Department confirmed it is currently testing the lake for toxins several times a week. In their notice to residents, the Health Department made it clear that it is safe to swim or play in water that is not green with algae, and that local drinking water supplies have not been affected. However, they do not advise that people or pets drink or play in water that is green with algae.

“The dying algae contain cynobacteria, which are a skin irritant,” added Grovanz. “Cynobacteria can release toxins that cause rashes and welts with repeated contact.”

The Health Department advises that if contact with algae does occur, simply wash the plant material off with soap and water.