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.

It seems shark sightings are dominating headlines on Long Island and researchers are on a quest to find out why more sharks are showing up in Long Island waters. NewsdayTV meteorologist Rich Von Ohlen discusses how to stay safe.  Credit: Newsday/A. J. Singh; Gary Licker

'Beneath the Surface': A look at the rise in shark sightings off LI shores It seems shark sightings are dominating headlines on Long Island and researchers are on a quest to find out why more sharks are showing up in Long Island waters. NewsdayTV meteorologist Rich Von Ohlen discusses how to stay safe. 

It seems shark sightings are dominating headlines on Long Island and researchers are on a quest to find out why more sharks are showing up in Long Island waters. NewsdayTV meteorologist Rich Von Ohlen discusses how to stay safe.  Credit: Newsday/A. J. Singh; Gary Licker

'Beneath the Surface': A look at the rise in shark sightings off LI shores It seems shark sightings are dominating headlines on Long Island and researchers are on a quest to find out why more sharks are showing up in Long Island waters. NewsdayTV meteorologist Rich Von Ohlen discusses how to stay safe. 

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