Because of the confirmed presence of blue-green algae, residents are asked to avoid using the waters of Forge Pond and Peconic Lake in Calverton, Suffolk County health officials said Friday.

The blooms also have returned to Old Town Pond in Southampton, with the algae’s presence there earlier reported on June 24.

Pets and children should be kept away from the areas, officials said.

Similar precautions should be taken with other locations with blue-green algae: Spring Lake, Middle Island; Setauket Mill Pond, Setauket; Wainscott Pond, Wainscott; Georgica Pond, East Hampton; Mill Pond, Watermill; Maratooka Pond, Mattituck; Agawam Lake, Southampton.

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Any water looking “scummy or discolored should be avoided,” officials said in a news release. If contact does occur, rinse off with clean water and see a doctor for symptoms that can include nausea, vomiting or diarrhea; skin, eye or throat irritation; allergic reactions or breathing difficulties, the health department said.

Blue-green algae, also known as cyanobacteria, is naturally present in low numbers, but can increase, forming blooms of green, blue-green, yellow, brown or red, as well as floating scum, the county health department said.