Nassau County health officials are telling swimmers to stay out of the water at three South Shore beaches.

The county Department of Health advised Monday against swimming at Hewlett Point Beach in East Rockaway, Island Park Beach in Island Park and the Merrick Estates Civic Association Beach in Merrick.

The advisory is a precautionary measure for beaches known to have substantial stormwater runoff caused by heavy rainfall. The runoff can raise bacteria levels, which results in the waters failing to meet New York state standards for swimming, health officials said.

The advisory will be lifted at 8 a.m. Tuesday unless there is additional heavy rainfall or water samples reveal elevated bacterial levels, the county said.

In Suffolk County, six beaches overall remained under a swimming advisory on Monday, health officials said.

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Four are in Babylon: Amityville Village Beach, Tanner Park Beach, Venetian Shores Beach and Copiague Harbor (Great South Bay); and two are in Huntington: Gold Star Battalion Park Beach and Centerport Yacht Club Beach.

Suffolk had advised against swimming at 62 beaches on Friday.

Suffolk County’s Department of Health Services said Lake Ronkonkoma (Islip) and Benjamin Beach in Bay Shore remained closed to swimming because of elevated bacteria levels.

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.

For updates in Suffolk, call the bathing beach hotline at 631-852-5822 or check the health department’s beach monitoring Web page at suffolkcountyny.gov/Departments/HealthServices.aspx.