A treatment to kill off an aquatic weed in Cayuga Lake was applied on the wrong day —

Thursday — in Don's Marina near the Town of Genoa, and now residents are being told not to drink water from a public water system or swim in the treatment area.

The United States Army Corps of Engineers was planning on treating a patch of hydrilla near Don’s Marina with the chemical Endothall next week, and residents were notified of the application.

However, because of miscommunication on the part of the certified pesticide applicator, Endothall was applied Thursday at Don's Marina, according to the Cayuga County Health Department.

There is one public water system intake in the notification area. Although no impacts are anticipated, the users of this system, Atwater Association, have been advised as a precautionary measure not to drink the water until samples collected by the Army Corps, in consultation with the Health Department, show that the herbicide is not detected in drinking water. The Health Department expects results by Aug. 23.

The notification boundary area includes a half-mile north and half-mile south of Don’s Marina. People should not swim in the treatment area and notification area to allow for adequate mixing of the product in the water.

Those who come in contact with the chemical by swimming could experience swim irritation or respiratory issues, said Eileen O'Connor, director of environmental health at the county Health Department.

"It is unlikely, because it dissipates quickly," O'Connor said. "If they experience symptoms, they should see their medical provider."

There are no restrictions on fishing, boating or using the water for irrigation. Additionally, there are no restrictions for use of the Endothall treated water for watering animals.

For people who draw water from the lake for use in their homes, the New York State Department of Health advises that people should never drink untreated lake water (water that is drawn from the lake, at any depth) under any circumstances regardless of whether Endothall is applied to areas of Cayuga Lake. Untreated lake water might contain bacteria, parasites, viruses and harmful algal blooms.

These contaminants can cause symptoms such as diarrhea, nausea and vomiting. Young children, pregnant women, older adults and people with health issues are at higher risk from symptoms associated with these contaminants. People should never use untreated lake water for drinking, making ice, washing produce, preparing foods, making baby formula or washing dishes.

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