Lake Elmo Water Tests Positive For Toxic Algae

Earlier this week, my co-worker promised her kid she would take him to Lake Elmo this weekend. After I told her about this development, they'll be skipping Lake Elmo. You and your dog will probably want to avoid the water as well.

Water samples collected from Lake Elmo in Billings on August 26 tested positive for cyanobacteria toxins, more commonly known as a harmful algal bloom, or HAB. The samples were sent to the Montana Department of Environmental Quality's laboratory in Helena for toxicity testing.

FW&P says Billings has received plenty of rain since the samples were collected, along with cooler temperatures. Those conditions can help reduce the likelihood of HABs, which typically thrive when water temperatures and nutrient levels are high.

FW&P will continue monitoring Lake Elmo and reporting its findings to DEQ.

When I stopped by today (9/3) to get some photos, I didn't immediately spot any particularly nasty-looking water along the shore, but you can't tell if HABs are present by looking at it. Two people were swimming.

What Exactly Is a Harmful Algal Bloom?

Despite the name, HABs aren't actually made up of algae. They're caused by cyanobacteria, sometimes called blue-green algae, that naturally occur in Montana's lakes, reservoirs, and streams.

Under the right conditions, those organisms can multiply rapidly and form a bloom. Importantly, not every bloom produces toxins. Water sampling is necessary to determine whether toxins are present.

HABs can look like spilled paint, pea soup, or grass clippings floating on the water. They can also produce unusual blue, green, red, or other discoloration and may have an unpleasant smell.

Cattails on the shore of Lake Elmo. Credit Michael Foth, TSM

A Labor Day Weekend Reminder

Labor Day weekend is practically a Montana holiday for getting outside. There will undoubtedly be people fishing, boating, paddleboarding, swimming, and letting the dogs enjoy the water before fall takes over.

FWP recommends avoiding water that looks discolored, has scum on the surface, or smells unusual. Keep children and pets away from suspected blooms, and don't let your dog drink the water. Pets and livestock can become seriously ill and even die after ingesting cyanotoxins.

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If you or your pet accidentally comes into contact with a suspected HAB, rinse off with clean tap water as soon as possible.

When in Doubt, Stay Out

That's the advice Montana DEQ gives on harmful algal blooms. Exposure to cyanotoxins can cause skin, eye, nose, and throat irritation.

Ingesting contaminated water can lead to symptoms including nausea, vomiting, diarrhea, headaches, and dizziness, while more serious exposure can cause muscle weakness or damage to the liver and kidneys.

Check the state's HAB information and reporting system for current reports and health advisories.