Minnesota Pollution Control Agency

Contacts: Steve Heiskary, 651-296-7217 (technical) Ralph Pribble, 651-296-7792 (media) St. Paul, Minn. -- As the thermometer climbs and a string of rainless days stretches on across parts of the state, some area lakes are starting to "green up." The Minnesota Pollution Control Agency (MPCA) reminds people that these conditions can produce a type of algae in lakes and rivers that can harm pets, livestock and even people. On Wednesday, MPCA staff doing water monitoring on Goose Lake in White Bear Lake observed a number of dead bullheads in the water and on shore. The MPCA is checking on possible causes, but a severe bloom of algae in the lake may be a factor. "Conditions are now ripe for creating severe algae blooms," said MPCA lakes expert Steve Heiskary. "We're starting to get reports and inquiries from around the state about algae, and people are especially concerned about blue-green algae." While not all algae blooms in Minnesota lakes and rivers this time of year are harmful, a type called blue-green algae can produce toxins that can harm animals and people. Heiskary is part of an interagency work group that's spreading the word that blue-green algae should be avoided. "When in doubt, best keep out," says a poster the group has distributed around the state. Algae are microscopic aquatic plants, and are a natural part of any aquatic ecosystem. There are hundreds of species. Under the right conditions, algae populations can "bloom" with dramatic growth, turning the water cloudy and green, a sight familiar to most summer-time lake-goers. Most algae blooms are harmless. But blue-green algae, when present in the water in high concentrations, can produce potent toxins that can affect humans or animals. Blue-green algae are found throughout Minnesota, but thrive particularly in warm, shallow, nutrient-rich lakes. Not every blue-green bloom is toxic, but it can be difficult to predict which ones will cause problems. High concentrations seem to be needed to produce harmful conditions. Often the algae can be concentrated when the wind blows them to a windward shore. Most problems occur when the algae concentrate around a shoreline and animals drink the water or otherwise ingest the algae. Harmful effects on humans are not often reported, probably because the unpleasant appearance and odors 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 non-experts. But toxic blooms generally look pretty nasty, sometimes said to look like pea soup, spilled green paint or floating mats of scum. They often smell bad as well. While such conditions would seem to keep most people away, it's surprising how many still will swim or wade in such waters or let their animals enter it. "You don't have to be an expert to recognize water that might have a toxic algae 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, go to/water/clmp-toxicalgae.html, or call 651-296-6300 or 800-657-3864.