Toxic algal bloom reported at Hebgen Lake

A toxic algal bloom has been confirmed along the north shore of Hebgen lake, posing a potential health threat to people, pets or livestock who come into contact with it, the Gallatin City-County Health Department said Wednesday.

The bloom, appearing as a green or turquoise scum along the lake surface, contains a toxin that, if ingested, can result in illness or death, the department says.

Symptoms including muscle twitching, staggering, convulsions and paralysis, with livestock that drink large amounts of water and pets that lick scum from their fur at greatest risk. Domestic animals have died from drinking lake water during past algal blooms at Hebgen, the department said.

Health officials recommend that people avoid swimming or recreation along the lake’s north shore during the bloom, and also keep pets and livestock from entering the water.

The bloom was detected during routine monitoring by Northwestern Energy, the health department said. The utility assumed ownership of the dam and Madison hydroelectric project in 2014, purchasing it from PPL Montana.

With a toxic bloom identified, the health department says the lake will be tested on a weekly basis as long as the toxic conditions persist, and that it will provide further notification if conditions change.