The Nassau County Department of Health said Tuesday it is advising against swimming at five South Shore beaches because of bacteria concerns.

The advisory is a precautionary measure for beaches known to have substantial stormwater runoff, which can raise bacteria levels so the waters fail to meet the New York standards for swimming, health officials said.

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The agency said swimmers should stay out of the water at Biltmore Beach Club, Massapequa; Hewlett Point Beach, East Rockaway; Island Park Beach, Island Park; Merrick Estates Civic Association, Merrick; and Philip B. Healey Beach, Massapequa.

For recorded information on beach closings and openings in Nassau, call 516-227-9700. Health department representatives are available weekdays, from 9 a.m. to 4:45 p.m., at 516-227-9717.