Contact: Ralph Pribble, 651-757-2657
St. Paul, Minn. — When the summer sun shines and temperatures climb, conditions are ripe for Minnesota lakes to produce harmful algal blooms. The Minnesota Pollution Control Agency (MPCA) is again reminding people some types of algae can harm pets, livestock and even people.
The MPCA reminds residents that some types of algae can harm pets, livestock and even people.Algae are microscopic aquatic plants and are a natural part of any aquatic ecosystem. Under the right conditions, some forms of algae, particularly a type called "blue-green algae," can pose harmful health risks. People or animals may become sick if exposed to these blooms. In extreme cases, dogs and other animals have died after exposure to lake water containing toxic blue-green algae.
“High rainfall results in nutrient-rich runoff, which enters lakes and fuels algae growth. As sunlight increases and temperatures warm, we can anticipate blooms of blue-green algae on many lakes,” said MPCA lakes expert Steve Heiskary. Heiskary is a member of an interagency work group that is spreading the word that blue-green algae should be avoided. “When in doubt, best keep out,” advises a poster the group created.
Most algae are harmless. However blue-green algae, when sunlight and warmth cause them to “bloom” in dense populations, can produce toxins and other chemicals. There are many types of blue-green algae. They are found throughout Minnesota, but thrive particularly in warm, shallow, nutrient-rich lakes. Often blown toward downwind shorelines, it is in these blooms that humans and animals most often come in contact with blue-green algae, and where the risk of algal toxins is greatest.
Complicating matters is that not all blue-green algae are toxic. There is no visual way to predict if a blue-green algal bloom contains toxins and is harmful to humans or animals. And distinguishing blue-green algae from other types may be difficult for non-experts. But harmful blooms are sometimes said to look like pea soup, green paint, or floating mats of scum. They often are smelly as well.
“You don’t have to be an expert to recognize an algae bloom that might be harmful,” Heiskary said. “If it looks bad and smells bad, it’s probably best not to take chances with it.”
An animal that has ingested toxins from an algae bloom can show a variety of symptoms, ranging from skin irritation, vomiting, severe disorders involving the circulatory, nervous and digestive systems, and severe skin lesions. In worst cases, the animal may suffer convulsions and die.
Humans are not affected very often, probably because the unpleasant appearance and odors of a blue-green algal bloom tend to keep people out of the water. But human health effects can include irritation of skin, eyes and nasal passages, and nausea and vomiting. Extreme cases can produce paralysis and respiratory failure.
These factors make it important to take a preventive approach to dealing with potential harmful algal blooms. There are currently no short-term solutions to correct a blue-green algal bloom. Once a bloom occurs, the only option is to wait for weather changes, such as significant rainfall, a wind shift or cooler temperatures, to disrupt the algae’s growth. According to Heiskary, the key to solving algae problems long-term is to improve water quality by decreasing the amount of nutrients that runoff carries into lakes.
For more information about harmful algae blooms, go to www.pca.state.mn.us/water/clmp-toxicalgae.html or call 651-296-6300 or 1-800-657-3864.
