2026 Weekly Cyanobacteria Emails to the Community

Week 3 brought cyanobacteria blooms to several regions of Lake Champlain, with 14% of monitoring reports indicating bloom conditions. Missisquoi Bay recorded the highest percentage of blooms relative to the number of reports received, with one-third of monitoring reports documenting bloom conditions. 

The second week of monitoring brought the season's first widespread reports of cyanobacteria blooms, with monitors documenting green surface accumulations and shoreline scums at several locations around Lake Champlain and inland lakes. The Category 3 bloom pictured above, reported from Philipsburg, Québec, formed a dense, spilled-paint-like scum that extended along the shoreline.

The first week of the 2026 cyanobacteria monitoring season (6/14 - 6/20/2026) kicked off with rainy weather and a range of generally safe conditions around Lake Champlain - though some phenomena including turbid waters, pollen-filled shorelines, and rocky habitats coated with filamentous green algae provided a good early test in identifying circumstances that are not cyanobacteria. 

Thank you to our volunteer monitors for a great first week of tracking water quality across the basin!