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Blue Green Algae

Blue-green algae, or cyanobacteria, are bacteria present in freshwater lakes and marine environments, like the Prospect Park Lake and other bodies of water in the NYC area. While they usually exist in low numbers, this type of algae can bloom during the summer months, which gives the water the appearance of neon blue or green paint. Certain types of cyanobacteria produce toxins, and during a bloom, ingestion or skin contact with these toxins can pose a health risk to humans and animals.

The Prospect Park Alliance is working closely with NYC Parks and the New York State Department of Environmental Conservation to test the biology of Prospect Park’s Lake on a weekly basis to monitor for blooms. Recent tests have indicated the presence of blooms near the Peninsula, but not at Dog Beach.

Where can dogs swim?
To minimize the risk of exposure to blooms, the Peninsula has been closed to dog swimming, Dog Beach currently remains open and will be monitored on a weekly basis. Please continue to check this website for updates as environmental conditions may change the presence of algal blooms.

Where can you fish?
Fishing information, including permitted fishing locations, can be found on our Fishing page.

What to do if exposure occurs
If a person or pet is exposed to a blue-green algae bloom, rinse with clean water. Seek medical attention if symptoms such as skin, eye or throat irritation; allergic reactions or breathing difficulties; nausea, vomiting, diarrhea, dizziness, headache or fever occur

For more about algal blooms, visit the NYC Parks website.