Blue-Green Algae Harmful To People, Pets And Livestock

(UNDATED) – The Indiana Department of Environmental Management (IDEM) and the Indiana Board of Animal Health (BOAH) is warning Hoosiers about the dangers of blue-green algae blooms in lakes and reservoirs as temperatures get warmer. Blue-green algae blooms typically occur in Indiana from late spring to early fall and may produce toxins that can be harmful to people, pets and livestock. 

blue-green algae

According to BOAH, dogs are particularly susceptible to blue-green algae poisoning because the scum can attach to their coats and be swallowed during self-cleaning. More information about protecting pets and livestock from harmful algal blooms can be found on BOAH’s blue-green algae website

Each year, IDEM samples water from state parks and state recreation area beaches for blue-green algae toxins. Water sample results and alerts are posted to IDEM’s Indiana Reservoir and Lake Update website and the public is encouraged to review this website before heading to lakes or recreational areas.

Water containing high levels of blue-green algae may appear greenish in color and, occasionally, some shades of blue, brown or white. Some appear to have a thick, paint-like scum on the surface. Blooms may appear for only a few hours or remain unchanged for weeks, depending on water and wind conditions. Factors that promote significant algal growth, or blooms, include sunlight, warm weather, low turbulence, and nutrient sources such as phosphorus and nitrogen. 

Public health officials suggest avoiding contact with waters visibly impacted by algae, and showering or bathing with warm, soapy water after recreating in reservoirs, lakes, rivers, and streams. For more information on blue-green algae, visit