In cooperation with the Idaho Department of Environmental Quality (DEQ), Public Health – Idaho North Central District is issuing a health advisory due to the presence of a harmful algal bloom in Mann Lake which is located about 5 miles east of Lewiston, Idaho.
Recent water samples taken from Mann Lake found high concentrations of blue-green algae (cyanobacteria) and the toxins they can produce are present in the Lake. Cyanobacteria occur naturally, but under certain conditions, some types of algae can release toxins into the water that are harmful to people, pets, and livestock. The blooms are generally green, or blue-green, and may form thick mats along shorelines. These may look like a surface scum, resembling pea soup and can have an unpleasant odor or stench.
Algae blooms are know to occur during hot and dry conditions; however, this rarely results in a water body and fishery closure. Usually, Idaho Public health issues a heath advisory alerting the public of the situation and to take precautions. However, due to the high levels of blue-green algae and the toxin in the water, the Lewiston Orchards Irrigation District and Idaho Department of Fish and Game felt extra precautions needed to occur and is why the reservoir is closed. When water quality conditions improve, Mann Lake will reopen.
You can read Public Health - Idaho North Central District's news release and health advisory for Mann Lake by following this link Mann Lake Health Advisory You can also read more about harmful algal blooms, including a map of advisories currently in effect throughout Idaho, by visiting DEQ’s website at Cyanobacteria Harmful Algae Blooms