The season summary status of Cyanobacteria (Blue-green Algae) shown on the map reflects conditions from early June through early November of 2017.
At most sites, observations and samples were collected once each week. Each dot on the map represents a testing site. Click on a test site on the map to display that site's results for the season
Download 2017 summary data.
Learn what blooms look like so you can avoid them.
See photos of what cyanobacteria blooms look like here.
What are Cyanobacteria?
Cyanobacteria, also known as blue-green algae, are a natural component of marine and fresh water ecosystems. Under certain conditions, cyanobacteria multiply quickly, creating blooms. Some blooms produce toxins which can make people and pets sick. Learn more about cyanobacteria (blue-green algae).