Health Alert: Harmful Algal Bloom Seasonal Awareness

Published on May 21, 2026

HAB Alert: avoid harmful algal blooms; habs are toxic to people and animals. rinse self or pet if contact occurs and seek medical care.

Tompkins County Whole Health (TCWH) is reminding the community that cyanobacterial blooms, also known as Harmful Algal Blooms (HABs), are known to appear on Cayuga Lake and other calm bodies of water (including ponds) throughout the summer months and into the fall. TCWH encourages residents and visitors to be aware of HABs, as blooms have already been reported in the northern parts of Cayuga Lake. With Memorial Day weekend coming up and summer just around the corner, it is important to take precautions when accessing our local waterways, as HABs produce toxins that are harmful to people and animals.

What are HABs?

HABs often form after periods of intense rain or runoff events and following periods of hot temperatures. HABs vary in appearance, but may include bright green colored water, a paint-like appearance, blue-green oily swirls, parallel green streaks, floating mats or scum. These algal blooms may vary in size and be confined to specific areas of the shoreline and bays, though they can form in open waters as well. View this video for more information about identifying HABs.

When in doubt, stay out

People recreating in and on the water should be aware of the potential for HABs in any waterbody they consider using. Because it is hard to tell a HAB from non-toxic algal blooms, it is best to avoid swimming, boating, otherwise recreating in, or drinking water with a bloom. Areas where blooms are not observed can continue to be safely used for recreational use.

If a HAB is suspected:

  • Do not drink and avoid contact with the water if it appears discolored or has an unpleasant odor.
  • Do not allow pets to drink or swim in water where suspicious HABs are present.

If you come into contact with a HAB:

  • Rinse thoroughly with clean water to remove cyanobacteria.
  • Stop using the water and seek medical attention immediately if symptoms such as vomiting, nausea, diarrhea, skin, eye or throat irritation, allergic reactions or breathing difficulties occur after drinking or having contact with blooms or untreated surface water.

Exposure to HABs is extremely dangerous for animals. If your dog comes into contact with suspicious HABs from swimming in, eating scum, drinking the water, or self-grooming after being in the water, it is important to:

  • Rinse and dry dogs thoroughly.
  • Monitor your pet for signs of toxin poisoning and seek immediate veterinary care. Signs of toxin poisoning can occur within 30 minutes to a few hours after exposure, depending on the size of the dog and how much toxin the dog has ingested. If left untreated, cyanobacterial poisonings are usually fatal in dogs.
  • For emergencies, contact the Cornell Veterinary Emergency Hotline: (607) 253-3060.

Testing and Reporting:

Blooms can be tested to determine if toxins exist. TCWH tests samples at regulated beaches when blooms are reported. These beaches include: Jennings Pond, Myers Point, Ithaca Yacht Club, Ithaca Zen Center, and Comstock Camp. If a bloom is sighted, the beach is closed, and information is posted, a sample is collected, and the beach reopens once a negative result is received.  

Doug Barnes, Senior Environmental Health Specialist states, “Blooms are often transient, typically lasting only a few hours. However, without testing, it is difficult to know if an area of water is safe to use. During these summer months, we urge the community to be aware, know what to look for, and avoid the area if it appears discolored or has an unpleasant odor.”

HABs can also be present in smaller ponds. Residents who have private ponds should monitor their ponds for signs of blooms and avoid contact. Residents may contact Soil and Water Conservation District at 607-257-2340 for guidance on pond management and a possible site visit to view the suspicious bloom. If a private resident is interested in testing a bloom, please contact the Community Science Institute (607-257-6606) to determine testing options and fees.

The Community Science Institute (CSI), Cayuga Lake Watershed Network, and Discover Cayuga Lake lead a volunteer program to monitor the Cayuga Lake shoreline for HABs during the summer months. Check for current HABs activity on Cayuga Lake using CSI’s interactive map, online at: http://www.database.communityscience.org/hab.

To report a HAB:

  • If you see a suspicious bloom in Cayuga Lake, stay out of the water and report the sighting to the Cayuga Lake HABs Monitoring Program by using their reporting form: 2026 Community Member Cayuga Lake HABs Report Form.
  • If you see a suspicious bloom in another public body of water, stay out of the water and report the sighting to the NYSDEC by filling out and submitting a Suspicious Algal Bloom Report Form, online at: NYSDEC HABs Report or email HABSInfo@dec.ny.gov if you are unable to complete the form.

Learn more about HABs online at: Harmful Algal Blooms (HABs) | Tompkins County

Tompkins County Whole Health: envisioning a future where every person in Tompkins County can achieve wellness. Find us online at: https://www.tompkinscountyny.gov/health and follow us on Facebook, Instagram or X. Sign up to receive Whole Health updates or other county announcements via email or text.

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