BLACK LAKE -- Laboratory testing has confirmed a blue-green algae bloom in Black Lake that can have harmful health effects on humans and pets.

The St. Lawrence County Public Health Department has issued a Blue-green Algae Advisory for the lake, in the northwest of the county, due to potential harmful effects such as skin or eye irritation, or diarrhea and vomiting if ingested.

The department warns that people and animals should keep out of the water where blooms are present and should rinse off with clean water if contact occurs.

Results from Citizens Statewide Lake Assessment Program (CSLAP) sampling efforts on Aug. 4 confirmed the presence of an open water cyanobacteria HAB in the lake based on a blue-green chlorophyll a level above the DEC confirmed bloom threshold. Further confirmation came from a microscopic analysis that found the blue-green algae glaucospira, dolichospermum, microcystis, and anabaena, and filamentous green algae.

A shoreline sample confirms a cyanobacteria bloom characterized as “Widespread/Lakewide.”

Black Lake, the largest lake in the county, borders on the towns of Hammond, Rossie, Macomb, Morristown, Oswegatchie and DePeyster.

The Public Health Department recommends taking the following precautions:

• Don’t swim, wade or fish near blooms or scums

• Don’t drink the water

• Keep children and animals away from any blooms or scums

• Rinse with clean water if exposed.

The department asks that people report to their primary care provider any symptoms that may be associated with exposure to blue-green algae blooms, such as skin or eye irritation, or diarrhea and vomiting.

For more information, visit https://www.stlawco.org/Departments/PublicHealth/.

There is more about blue-green algae at www.health.ny.gov/harmfulalgae and www.dec.ny.gov/chemical/77118.html .