Toxic algae prompts warning at Cow Creek Reservoir -

State of Montana NewsRoom

Montana Government News


Toxic algae prompts warning at Cow Creek Reservoir

Monday, September 9, 2019/Categories: Department of Environmental Quality/Tags:

CHINOOK – Blaine County health officials reported Wednesday that toxic, blue-green algae has been found in Cow Creek Reservoir, southwest of Chinook.


On Sunday, September 1, Blaine County was alerted that a woman’s 10-month old puppy had died after drinking water immediately below the outfall of Cow Creek Reservoir. On Wednesday, September 4, a qualitative water sample test was positive for the presence of microcystin, a known liver toxin, at or above the advisory level for recreation.


The Blaine County Sherriff’s office has posted five of the state Harmful Algal Bloom program’s caution signs at the Reservoir.


The Montana Department of Environmental Quality, the Department of Public Health & Human Services and the Blaine County Health Department strongly recommend that people stay out of any water where algal blooms are seen. Children and animals are most at risk because they can accidentally ingest the water as they spend time wading in shallow water where the algae tends to accumulate. Pets and livestock should also be kept away from water that has an algal bloom.


These types of algal blooms are native to freshwater lakes and reservoirs in Montana. They tend to grow in warmer water and where there’s an increase in nitrogen and phosphorus runoff from a variety of human activities. They become increasingly common this time of year. The algae blooms float on the surface of the water and may look like pea soup, grass clippings, or green latex paint.


If you see what you think might be a harmful algae bloom, you can report it using the Montana Department of Public Health and Human Services website at:  The site also has a map of reported HABs and information on how to identify them.


If you suspect a toxic algae-related illness in a person or animal, including livestock, call Poison Control immediately at 1-800-222-1222 and/or contact Blaine County Sanitarian Ron Andersen at: 406-868-4957


Number of views (1329)/Comments (0)

Please login or register to post comments.