ST. PAUL, Minn. - A heatwave that will envelop Minnesota and western Wisconsin this week is bringing with it warnings that conditions are ripe for lakes to produce harmful algae blooms.
The Minnesota Pollution Control Agency (MPCA) is reminding people that some types of algae can harm pets, livestock and even humans.
"High rainfall, which has been common throughout much of Minnesota this spring, results in nutrient-rich runoff entering our lakes, fueling algae growth," MPCA lakes expert Steve Heiskary said. "While spring and early summer temperatures were cooler than normal, lake temperatures have warmed rapidly. Given these conditions, we are likely to see blue-green algae blooms on many of our lakes."
Algae, microscopic aquatic plants, are a natural part of any aquatic ecosystem. Most algae are harmless, but under the right conditions certain types of algae can pose health risks. People or animals may become sick if they touch or ingest affected water.
In extreme cases, dogs and other animals have died after exposure to lake water containing toxic blue-green algae.
Blue-green algae thrives particularly in warm, shallow, nutrient-rich lakes. It is often blown into shorelines, where humans and animals most come in contact with blue-green algae. It is also there that the risk of algal toxins is greatest.
The MPCA says harmful blooms are sometimes said to look like pea soup, green paint, or floating mats of scum, and they often have a bad odor.
"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, don't take a chance. Stay out and keep children and pets away from the water until the bloom subsides."
An animal that has ingested toxins from an algal 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 rarely affected, probably because the unpleasant odor and appearance of a blue-green algal bloom tend to keep people out of the water. Still, warnings of human exposure include irritation of skin, eyes and nasal passages, and nausea and vomiting. Extreme cases can produce paralysis and respiratory failure.
Once a bloom occurs, the only option available is to wait for weather changes, such as significant rainfall, wind shifts or cooler temperatures, to disrupt the algae's growth.
For more information, go to the MPCA's Blue-green Algae and Harmful Algal Blooms webpage.
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