Panguitch Lake has been closed because of “extremely high toxin levels” from an ongoing algal bloom, according to the Southwestern Utah Health Department (SUHD).

Closure signs were being posted Monday at the Garfield County lake after results from a Sept. 12 test showed levels of microcystin — also known as blue-green algae — from the cyanobacteria bloom were 12.5 times the threshold for a danger advisory. And, according to the SUHD, those levels could go even higher.

According the Environmental Protection Agency, the toxins “may persist for weeks to months.”

The Utah Department of Agriculture and Food was contacting livestock owners in the area to alert them to the danger from the toxins, recommending they prevent their cattle from drinking from the reservoir or downstream from the lake.

The Division of Water Quality planned to collect more samples from the lake Monday.