The New York State Department of Health (NYSDOH) has established guidance values for total microcystins of 0.3 μg/L for public drinking water supplies and 4.0 μg/L for public swimming beaches (EPA, 2015).

Both suspected and confirmed HABs should be avoided by people and pets. Questions regarding drinking water, recreational water use, or potential exposure should be directed to NYSDOH or your local county health department:

• NYSDOH: harmfulalgae@health.ny.gov
• Tompkins County Whole Health: (607) 274-6688
• Cayuga County Health Department: (315) 253-1560
• Seneca County Health Department: (315) 539-1945

All confirmed HABs reported directly to CSI are also submitted to the New York Harmful Algal Bloom System maintained by the New York State Department of Environmental Conservation.

This webpage is designed to:

1. Quickly alert you to recent reports of cyanobacteria blooms (HABs)
2. Provide detailed information about each HAB reported
3. Make it possible to analyze long-term patterns of HABs occurrences.

All HAB reports listed are confirmed. Here's how confirmation works:

1. Visual assessment: A bloom is first documented visually, following the NYSDEC Harmful Algal Bloom Program Guide (Section 4: Bloom Reporting).
2. Microscopic examination: Submitted samples are then examined under a microscope to confirm cyanobacterial dominance.
3. Microcystin testing: Total microcystin results reflect only the submitted sample. They don't represent toxin levels across the whole bloom, or at other locations or times.

CSI's Cayuga Lake HABs Monitoring Program was launched in 2018, recording HABs and their location, approximate size, density, genera of cyanobacteria it contained, and concentration of microcystin (a toxin created by the most commonly detected genera of cyanobacteria on Cayuga Lake).

The reporting of bloom occurrences in this database is organized by geography and by areas of recreational interest, for example, parks and boat launches. Thus, Cayuga Lake is divided into 34 shoreline segments and four open water segments for a total of 38 segments used to track HABs spatially along the shore and in the open water of Cayuga Lake.