Bacterial runoff from heavy rainfall prompted Suffolk health officials to issue an advisory Monday against swimming at 47 beaches. The officials recommended that bathers keep out of the water at least until Tuesday morning.

"The advisory is based on the potential that bacterial numbers in excess of New York State standards, resulting from the heavy rain that occurred last night," the Suffolk County Department of Health Services said.

The beaches are subject to heavy stormwater runoff from the surrounding watersheds and waterways, or are located in enclosed bays with limited tidal flushing, officials said.

"The department recommends that bathing and other water contact be suspended in affected areas until the waters have been flushed by two successive tidal cycles (at least a 24-hour period) after the cessation of rainfall," the advisory said.

"The advisory will be rescinded at 6 a.m. Tuesday morning ... unless sampling done by the department finds elevated bacterial numbers persisting beyond the 24-hour period," the Suffolk health alert said.

The county offers more information on beach closings on its hotline, at 631-852-5822, or at suffolkcountyny.gov/health.

Here are the 47 affected beaches:

Asharoken Beach

Bay Hills Beach Association, Huntington Bay

Bayberry Cove Beach, Setauket-East Setauket

Baycrest Association Beach, Huntington Bay

Bayview Beach, Setauket-East Setauket

Beech Road Beach, Rocky Point

Broadway Beach, Rocky Point

Callahans Beach, Smithtown

Centerport Beach

Cold Spring Harbor Beach Club Beach

Crab Meadow Beach in Northport

Crescent Beach, Huntington Bay

Eagle Dock Community Beach, Cold Spring Harbor

Fleets Cove Beach, Huntington

Friendship Drive Beach, Rocky Point

Gold Star Battalion Park Beach, Huntington

Grantland Beach, Setauket-East Setauket

Head of the Bay Club Beach, Huntington Bay

Hobart Beach, Northport

Huntington Beach Community Association Beach, Centerport

Indian Field Beach, Setauket-East Setauket

Knollwood Beach Association Beach, Huntington

Little Bay Beach, Setauket-East Setauket

Lloyd Harbor Village Park Beach

Lloyd Neck Bath Club Beach

Long Beach, Nissequogue

Miller Place Park Beach

Nathan Hale Beach Club Beach, Huntington Bay

Nissequogue Point Beach

Prices Bend Beach, Eatons Neck

Schubert Beach, Nissequogue

Scotts Beach, Sound Beach

Shoreham Beach, Shoreham

Shoreham Shore Club Beach, East Shoreham

Shoreham Village Beach

Short Beach, Nissequogue

Sound Beach POA West

Soundview Beach Association Beach, Old Field

Steers Beach, Northport

Stony Brook Beach

Stony Brook Yacht Club Beach

Terraces on the Sound, Rocky Point

Tides Beach, Sound Beach

Valley Grove Beach, Eatons Neck

West Neck Beach, Lloyd Harbor

Wincoma Association Beach, Huntington Bay

Woodhull Landing POA Beach, Miller Place

Newsday travel writer Scott Vogel took the ferry over to Block Island for a weekend of fun. Credit: Randee Daddona

Updated now Newsday travel writer Scott Vogel took the ferry over to Block Island for a weekend of fun.

Newsday travel writer Scott Vogel took the ferry over to Block Island for a weekend of fun. Credit: Randee Daddona

Updated now Newsday travel writer Scott Vogel took the ferry over to Block Island for a weekend of fun.

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