A beach on Lake Hopatcong is closed to the public after two rounds of water testing in the area showed high levels of harmful algae blooms (HABs).
Colleen Lyons, administrator of the Lake Hopatcong Commission, confirmed the Crescent Cove Beach Club is closed due to sample results collected by the state Department of Environmental Protection Monday and last Wednesday, July 27.
The data on the DEP website showed concentrations of cyanobacteria, the type of algae in the blooms, at 450,000 cells per milliliter Monday and 308,750 cells per milliliter last week. Both readings are well above the threshold of 80,000 cells per milliliter that triggers an “advisory” from the state.
The latest test concentration is more than double the sample of 171,500 cells per milliliter taken in Crescent Cove July 15, which resulted in the lake’s first HAB advisory of the year. However, the beach remained open because the Sussex County Health Department determined the bloom did not affect the swim area.
The DEP website also shows an advisory from another test taken July 27 on Lake Musconetcong, which is located downstream from Lake Hopatcong and is part of its watershed. The Lake Musconetcong sample had a toxic algae concentration of 189,000 cells per milliliter.
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The DEP recommends the public avoid “primary contact recreation” such as swimming and water-skiing in an area under an algae advisory. Drinking water and eating fish caught near the site are also discouraged. People should be cautious when performing “secondary contact activities” like fishing or boating.
Cyanobacteria, if ingested, can cause headaches, sore throat, nausea, abdominal pain, dry cough, diarrhea and blistering around the mouth. Direct contact with algae may lead to a skin rash. Animals exposed to cyanobacteria may experience lethargy, stumbling and loss of appetite.
Harmful algae grows more quickly in warm, nutrient-rich water, conditions lake officials say were prevalent in the area because of recent weather. The region experienced several days of high temperatures, and the heavy rain likely washed nutrients like lawn fertilizer and animal waste into the lake.
Last week, the Lake Hopatcong Commission authorized the use of an algaecide called GreenClean in a five-acre section of Crescent Cove to reduce toxic algae buildup in the area.