The South Dakota Department of Agriculture and Natural Resources (DANR) reminds the public to remain mindful when recreating on lakes around the state as harmful algal blooms (HABs) can develop rapidly and without notice during the summer. HABs can be harmful to people, pets, and livestock so please remember, When in Doubt, Stay Out!
HABs typically occur during July, August, September in nutrient enriched lakes and ponds, although they can occur earlier or later in the year depending on the conditions. In South Dakota, HABs are usually produced by blue-green algae, a primitive photosynthetic alga also known as cyanobacteria. Blue-green algae produce toxins that can be harmful to people (especially children), pets, and livestock. Be cautious when recreating during the summer and refrain from letting your pets drink from open water sources.
DANR and its partners collect toxin samples at lakes throughout the state and sample results are posted to an interactive web map.
The map shows toxin concentration levels at specific times and locations. The results should not be used to determine if waters are safe to use at any given time.