Health officials issue toxic algae advisory for Hebgen Lake

BOZEMAN (AP) — Health officials have issued a safety advisory for a lake just outside Yellowstone National Park after harmful algal blooms toxic to humans and animals were detected.

The bloom of algae was in Hebgen Lake, a reservoir in southwestern Montana near the borders of Idaho and Wyoming, officials said.

NorthWestern Energy monitors six locations around the reservoir weekly, said company spokesperson Jo Dee Black.

Warmer water temperatures and a lower-than-normal water level is causing more algae growth earlier in the season than in a typical year, Black told the Bozeman Daily Chronicle.

Blue-green algae is native to Montana's freshwater lakes and reservoirs and not all varieties are harmful.

But some algal blooms produce toxins that pose a risk to people, pets and livestock when ingested or through prolonged contact, according to NorthWestern Energy and the Gallatin City-County Health Department.

Symptoms can include muscle twitching, staggering, convulsions, paralysis and death. Children and pets are more at risk from the blooms, as they are more likely to involuntarily ingest the water and to wade in shallow waters.

Don't drink, swallow or swim in water that has harmful blooms, officials said. The blooms can look like pea soup, grass clippings or green latex paint and are typically suspended in the water and can appear as floating mats.