PHD Contact: Katherine Hoyer

August 28, 2019

(208) 415-5108

DEQ Contact: Robert Steed (208) 769-1422

Health Advisory Extended to Upper Twin Lake

KOOTENAI CO., ID — Panhandle Health District (PHD) and the Idaho Department of

Environmental Quality (DEQ) has issued a health advisory for Upper Twin Lake. The health advisory for Lower Twin Lake, including the channel, which is the narrow stretch of water that connects Upper and Lower Twin Lakes, remains in effect as well.

DEQ took samples at Twin Lakes (upper, lower, and the channel) on August 28 and found cyanobacteria, sometimes called blue-green algae or a harmful algal bloom (HAB), present in elevated levels in the upper lake. Scum was observed along the down-wind shoreline extending into the channel. Additionally, a localized scum was observed at the Idaho Fish and Game boat ramp in the channel.

PHD and DEQ are urging the public to use caution and avoid exposure when recreating in or near the water. Cyanobacteria have the potential to produce dangerous toxins in areas of the lake.

The physical appearance of these blooms can be unsightly, often presenting in discolored water, streaks, or globs of scum and causing thick green mats along lake shorelines. Those observed on August 28 had a ribbon-like appearance prior to condensing into scum. Pets, children, the elderly, and people with compromised immune systems are most at risk of harmful exposure.

Be cautious and avoid areas where scum has formed. Scums can form quickly and can change location depending on wind and weather conditions.

Anyone recreating near Twin Lakes is advised to take precautions to avoid exposure to lake water appearing to contain a HAB. Property 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 areas of the fish.

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

The public will be advised when the concern no longer exists. DEQ will continue to monitor Twin Lakes throughout the duration of the bloom. This advisory is to inform the public so they can make the best decision regarding recreation in the water.

Updated information on harmful algal blooms in northern Idaho can be found online at