For Immediate Release: July 30, 2026

A harmful algal bloom (HAB) has been detected in the Rainbow Point area of Hebgen Reservoir, and that area is closed for water-based activities because toxin levels are high. Routine monitoring of Hebgen shows the water contains anatoxin-a, a toxin made by certain algae that can make people, pets, and livestock very sick. Other parts of the reservoir are also being monitored, but those areas currently have lower toxin levels and remain open.  

Read the full press release here. 

Toxin exposure can occur in humans from recreational activities where water might be ingested such as swimming, wind surfing, jet skiing, and water skiing. Children and pets are more likely to ingest HAB infested water because they spend most of their time wading in the shallow waters where algae can accumulate and they have less control over how much water they ingest. Animals and livestock that drink large amounts of contaminated water, and pets that collect scum on their fur and then ingest it by licking, are at high risk of toxin exposure.