Nassau County's Department of Health issued an advisory against swimming at four North Shore beaches on Wednesday because of heavy rainfall the day before.

In addition, three South Shore beaches — Philip Healey Beach and Biltmore Beach Club in Massapequa and Hewlett Point Beach in East Rockaway — remain closed due to elevated bacteria levels, health officials said.

The health department advised residents against swimming at Morgan Sound in Glen Cove, North Hempstead Beach Park in Port Washington, Sea Cliff Village Beach in Sea Cliff and Tappen Beach in Glenwood Landing.

The advisory is a precautionary measure for beaches impacted by stormwater runoff caused by heavy rainfall. Stormwater runoff can impact bathing water quality by elevating bacteria levels above the state standards.

Health department officials said the advisory will be lifted at 7 a.m. Thursday unless there is additional heavy rainfall or water samples reveal elevated bacteria levels.

What began as a desperate hunt for Shannan Gilbert in the marshes near Gilgo Beach became, in three astonishing days in December 2010, the unmasking of a possible serial killer. NewsdayTV's Doug Geed has more.  Credit: Newsday/A. J. Singh; File Footage; Photo Credit: SCPD

'We had absolutely no idea what happened to her' What began as a desperate hunt for Shannan Gilbert in the marshes near Gilgo Beach became, in three astonishing days in December 2010, the unmasking of a possible serial killer. NewsdayTV's Doug Geed has more.

What began as a desperate hunt for Shannan Gilbert in the marshes near Gilgo Beach became, in three astonishing days in December 2010, the unmasking of a possible serial killer. NewsdayTV's Doug Geed has more.  Credit: Newsday/A. J. Singh; File Footage; Photo Credit: SCPD

'We had absolutely no idea what happened to her' What began as a desperate hunt for Shannan Gilbert in the marshes near Gilgo Beach became, in three astonishing days in December 2010, the unmasking of a possible serial killer. NewsdayTV's Doug Geed has more.

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