ST. GEORGE — The Southwestern Utah Health Department recently issued a danger advisory/closure for Panguitch Lake based on toxin levels in the lake from an ongoing cyanobacteria bloom. Closure signs will be posted Monday.
According the Utah Department of Environmental Quality, harmful algal blooms occur when normally occurring cyanobacteria in the water multiply quickly to form visible colonies or blooms. These blooms sometimes produce potent cyanotoxins that pose serious health risks to humans and animals.
Although most algal blooms are not toxic, the department said, some types of cyanobacteria produce nerve or liver toxins.
A statement posted on the Utah DEQ website regarding the closure identified ‘extremely high toxin levels’ and said the Utah Department of Agriculture and Food contacted livestock operators in the area to recommend they prevent their cattle from drinking water from the reservoir and downstream sources. UDAF advises producers to find alternative water sources until conditions improve.
Toxin test results from the Utah Public Health Lab for samples collected on Sept. 12 showed that microcystin levels after 5000x dilution were at least 12.5 times higher than the recreation health-based threshold for a danger advisory. Further dilutions by the lab will be necessary to quantify microcystin concentrations, and these levels could go even higher after these dilutions.
The Utah Division of Water Quality also collected samples from Panguitch Creek at the White Bridge Campground below Panguitch Lake on Sept. 18. Toxin test results were non-detect for anatoxin and >5 µg/L for microcystins. Further dilutions by the lab will be necessary to quantify microcystin concentrations, and the preliminary values could go even higher after these dilutions.
The Division of Water Quality and UDAF is visiting Panguitch Lake on Monday to collect further samples.
A danger advisory indicates a high relative probability of acute health risk, cell count densities greater than 10,000,000 cells/ml, microcystins levels greater than 2,000 µg/L, cylindrospermopsin levels greater than 8 µg/L or anatoxin-a levels greater than 90 µg/L.
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