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Posted on: August 21, 2023

Health Advisory Issued for Fernan Lake

Health Advisory

Panhandle Health District (PHD) in collaboration with the Idaho Department of Health & Welfare (IDHW) and Idaho Department of Environmental Quality (DEQ) have issued a public health advisory for Fernan Lake. Recent water sampling by DEQ indicates the presence of cyanobacteria, also known as a harmful algal bloom (HAB) in Fernan Lake. The public should take precaution throughout the lake as HABs can spread and move with wind and water traffic.  

Idaho’s active HAB advisories are listed here: 

Private domestic water system owners utilizing the lake as a drinking water source are cautioned that potentially present toxins cannot be removed by boiling or filtering the water. If contact (swimming, bathing, or showering) has been made with water containing a HAB, it is recommended to wash off with fresh water. 

If people choose to eat fish from the lake, it is recommended that they remove all fat, skin and organs before cooking, since toxins are more likely to collect in those tissues. 

Symptoms of exposure to HABs vary according to exposure. Symptoms can include rashes, hives, diarrhea, vomiting, coughing, and/or wheezing. More severe symptoms affecting the liver and nervous system may result from ingestion of water. If symptoms persist, consult with your health care provider or your veterinarian for pet exposure. 

Cyanobacteria are a natural part of Idaho’s water bodies. When temperatures rise, their populations can bloom and toxic chemical compounds, or cyanotoxins, can be released into the water. Caution should be taken anywhere the water appears discolored or murky as HABs can spread or move with wind and water currents. HABs have the potential to produce dangerous toxins especially when accumulated in high concentrations. The physical appearance of these blooms can vary, presenting as discolored water, streaks or globs of scum and can cause thick green mats along lake shorelines. Pets, children, the elderly, and people with compromised immune systems are most at-risk of harmful exposure. 

The public is urged to use caution when recreating in or near the water at Fernan Lake if the appearance of a HAB is present. 

For more information about harmful algal blooms, visit DEQ’s website at:

Idaho’s active HAB advisories are listed here: 

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