Cyanobacteria blooms, also known as HABs (Harmful Algal Blooms) have been observed at various locations in Cayuga Lake, including in Tompkins County, during the summers since 2017. Trained volunteers and local officials monitor much of the county shoreline for HABs on a weekly basis during the summer. These blooms may be small in size and confined to specific areas of the shoreline and bays. Blooms are often transient, typically lasting only a few hours.
Several types of cyanobacteria can produce toxins and other harmful compounds that can pose health risks to people and animals through ingestion, skin contact, or inhalation. 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-harmful 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 used for recreational use.
The Cayuga Lake Harmful Algal Bloom Monitoring Program is a collaborative of the Community Science Institute (CSI), Cayuga Lake Watershed Network, Discover Cayuga Lake and others established to monitor HABs development during the summer months.
Tompkins County Whole Health urges residents and visitors to beware of HABs. These blooms can occur in any calm body of water and may produce toxins that are harmful to people and animals.
There is no concern with municipal water supplies at this time. In the unlikely event that a public water supply is affected by HABs, the TCWH will work with the water supply to evaluate the situation and provide notice to affected users.
7/11/2025