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Despite opening Utah Lake for swimming Tuesday, the Utah County Health Department had issued a warning against water activities in Big East Lake in Payson Canyon after a toxin from an algal bloom contaminated the water.

The toxin, cyanobacteria, is considered dangerous at a frequency of 10 million cells per milliliter, according to the World Health Organization, but samples taken Thursday from Big East Lake had 45.6 million cells per mL — more than four times the concentration considered dangerous — a Utah Department of Environmental Quality news release said.

The specific species of cyanobacteria found in the lake is Gloeotrichia echinulata, which can cause gastrointestinal problems and skin rashes, the release said. Another cyanobacteria genus, Microcystis, was also found in the sample, but at "extremely low levels."

The health department announced it would post warning signs at the lake Wednesday, advising people to stay out of the water. Patrons are specifically asked to avoid swimming, boating and water skiing in areas with scum, and to avoid drinking lake water or allowing pets and livestock near the water, the release said. Health officials also advised anglers to "clean their fish well with nonlake water and discard the guts responsibly."

Last summer, several types of cyanobacteria forced the closure of Payson lakes, the release said.

County crews were collecting more samples Wednesday to conduct preliminary screening tests, the release said, to determine whether it was necessary to submit samples to a lab for more detailed toxin analysis.

Payson City stopped drawing water from the lake for its pressurized irrigation system and instead used water from Strawberry Reservoir, Spring Lake and wells and springs, the release said.

Though there is no reason for concern from residents, anyone interested in taking additional precautions, officials suggested running sprinklers after 10 p.m. and before 6 a.m. to avoid any exposure to the spray.

Children should avoid playing in the sprinklers, the release said, and concerned parties may contact the city offices at 801-465-5200 for more information.

Exposure to cyanotoxins, the toxins produced by cyanobacteria, may lead to headache, fever, diarrhea, abdominal pain, nausea, vomiting and skin rash, the release said. People concerned about possible exposure are asked to call the Utah Poison Control Center at 800-222-1222 or a physician. Anyone concerned about possible pet or animal exposure to animals should contact a veterinarian.

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