Advisory issued against swimming at 20 Nassau beaches

The Nassau County Health Department issued an advisory Sunday morning against swimming at 20 beaches, 16 on the North Shore and four on the South Shore.

The advisory was "a precautionary measure for beaches known to be impacted by stormwater runoff caused by heavy rainfall," the department said in its statement.

As of Sunday, Long Island has seen intermittent rain for the past 36 hours.

When rain falls on impermeable surfaces it carries animal feces — especially from domestic dogs when humans don’t pick up after them — into nearby streams and bays. Leaking cesspools and septic systems also contribute to the problem, according to Save the Sound's most recent beach report, released last week.

The advisory was issues for these North Shore beaches:

• Centre Island Sound — Bayville
• Creek Club — Lattingtown
• Crescent Beach — Glen Cove
• Lattingtown Beach — Lattingtown
• Laurel Hollow Beach — Laurel Hollow
• Morgan Sound — Glen Cove
• North Hempstead Beach Park — Port Washington
• Piping Rock Beach Club — Locust Valley
• Pryibil Beach — Glen Cove
• Ransom Beach — Bayville
• Theodore Roosevelt Beach — Oyster Bay
• Sea Cliff Village Beach — Sea Cliff
• Sea Cliff Yacht Club Beach — Sea Cliff
• Soundside Beach — Bayville
• Stehli Beach — Bayville
• Tappen Beach — Glenwood Landing

The advisory was issued for these South Shore beaches:

• Biltmore Beach Club — Massapequa
• Hewlett Point Beach — East Rockaway
• Island Park Beach — Island Park
• Philip Healey Beach — Massapequa

The health department said the advisory would end Monday morning unless heavy rain continued or if testing showed bacterial levels that exceed the standards for safe swimming.

Suffolk County had made no similar declaration by Sunday afternoon.