Minnesota Pollution Control Agency

Media contact: Jennifer Maleitzke, (651) 296-7706 Note to editors: A photo suitable for use with this news release is available in the News Media Center at www.pca.state.mn.us/newscenter/index.html. St. Paul, Minn. -- When the summer sun beats down and temperatures climb, conditions are ripe for Minnesota lakes to produce dangerous algal blooms. Toxic blue-green algae can harm pets, livestock and even people, according to the Minnesota Pollution Control Agency (MPCA). Blue-greens are a form of aquatic algae that normally occur in many Minnesota waters, but under the right conditions, they can become toxic. "High rainfall, resulting in nutrient-rich runoff entering our lakes fuels the growth of algae," said MPCA lakes expert Steve Heiskary. "Earlier this summer, cloudy and cool conditions served to minimize algal blooms. However, as sunlight increases and temperatures warm, we can anticipate blooms of blue-green algae on many of our lakes." Heiskary is a member of an interagency work group that's spreading the word that waters experiencing blooms of blue-green algae should be avoided. "When in doubt, best keep out," says a poster the group has distributed around the state. In addition to the MPCA, the work group includes the Minnesota Department of Natural Resources, the Minnesota Department of Health and the Minnesota Veterinary Medicine Association. Algae are microscopic plants that are a natural part of any aquatic ecosystem. There are hundreds of species. Under the right conditions, algae populations can "bloom," increasing so dramatically that they turn the water cloudy and green, a sight familiar to many summertime lake-goers. Most algal blooms are harmless. But blue-green algae, when present in high concentrations, can produce potent toxins that can harm people and animals. Blue-green algae are found throughout Minnesota, but thrive particularly in warm, shallow, nutrient-rich lakes. As algal concentration can vary widely across a lake, so can algal toxins. Often occurring on downwind shorelines, high algal concentrations may produce harmful conditions. It is these near-shore blooms where humans and animals most often come in contact with blue-green algae and where the risk of algal toxins is greatest. Harmful effects on humans are not often reported, probably because the unpleasant appearance and odor of a blue-green 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. Distinguishing blue-green algae from other types may be difficult for most people. However, toxic algal blooms generally look pretty nasty - like pea soup, spilled green paint or floating mats of scum. They often smell bad too. While such conditions would seem to keep most people away, it's surprising how many will swim or wade in such water or let their animals enter it. "You don't have to be an expert to recognize water that might have a toxic algal bloom," Heiskary said. "If it looks bad and smells bad, it's probably best not to take chances with it." For more information about toxic algae blooms call (651) 296-6300 or (800) 657-3864 or go to hhref="/water/clmp-toxicalgae.html.