Potentially toxic blue-green algae bloom detected at Mill Creek in Water Mill

Suffolk County health officials are warning residents and their pets to stay away from Mill Creek in Water Mill after water sample testing detected the presence of new blooms of potentially harmful cyanobacteria, which is more commonly known as blue-green algae.

Officials said the blue-green algae was found by Stony Brook University biologists, who took surface water samples, and is a health risk if residents use, swim, or wade in the waters.

Though blue-green algae are naturally present in lakes and streams in low numbers, they become harmful when they bloom or become abundant. Some species of cyanobacteria produce toxins that can cause health problems in humans and animals if exposed to large enough quantities, according to health officials.

Blooms can appear in shades of green, blue-green, yellow, brown or red, and at times produce floating scums on the surface or have a paint-like appearance.

If contact does occur with scummy or discolored water, rinse off with clean water immediately, officials said.

Hazardous algae blooms can be active for up to two weeks, may be present in all or parts of a waterbody, and may not reflect current conditions, the DEC said.

Harmful algae blooms were detected in 26 Suffolk water bodies in 2023, the most ever affected in the county in a single year since the DEC began tracking blooms statewide in 2012.

To report a suspected blue-green algae bloom at Suffolk County beaches open to swimming, residents can contact the Suffolk County Department of Health Services’ Office of Ecology at 631-852-5760 or email scdhsweb@suffolkcountyny.gov.

Algae blooms found at bodies of water not open to bathing can be reported to the DEC at habsinfo@dec.ny.gov.