Some species of cyanobacteria (bluegreen algae) can produce toxins harmful to people and animals. Toxins such as anatoxin-a and microcystin can be produced by blooms of these species. Anatoxin-a is a potent nerve toxin, and chronic exposure to microcystin can cause liver damage. Contact with water containing toxins can be enough to cause illness in humans, pets and livestock. Ingestion of the toxins can cause severe illness or death, sometimes within minutes or hours.

Harmful algae blooms (HABs) are most frequently observed in Anderson Lake but have also been seen in Lake Leland, Gibbs Lake, Crocker Lake and others. Check our Lake Status page for the most recent observations.

"Blooms" (run-away growth of cyanobacteria) are most common in summer but can also occur at any time of year. Toxins may be present during a visible bloom or may persist after a bloom has disappeared. Visible blooms can also be produced by diatoms, green algae or non-toxic cyanobacteria that are not harmful.

Report a Bloom

If you see a bloom on a Jefferson County Lake, please report it by calling 360-385-9444.