The South Central Public Health District and the Idaho Department of Environmental Quality issued a public health advisory Monday for Mormon Reservoir south of Fairfield.
Recent samples collected by the DEQ show unhealthy levels of a cyanotoxin, caused by high levels of cyanobacteria, a harmful algal bloom.
Since Aug. 11, Cedar Creek Reservoir south of Twin Falls and Thorn Creek Reservoir off of state Highway 46 near Little City of Rocks have also been under public health advisories for harmful algal blooms.
“These toxins can cause neurological problems, gastrointestinal distress, and irritate areas of your body like your skin, eyes, and ears,” South Central Public Health District Public Health Program Manager Josh Jensen said in Monday's press release.
Residents are advised to keep children and animals away from the water. Fishermen are advised to thoroughly clean any fish drawn from these reservoirs before eating them.