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Blue-green algae is in some KS, MO lakes. What is it, and should you be worried about it?

Big Eleven Lake in Wyandotte County
Big Eleven Lake in Wyandotte County tljungblad@kcstar.com

Toxic blue-green algae has been reported in several Kansas lakes and one Missouri lake in recent days, and officials are advising residents to stay away.

Big Eleven Lake in Wyandotte County and Shawnee Lake in Shawnee County are among the six Kansas lakes affected by current algae blooms. The Kansas Department of Health and Environment (KDHE) warned visitors about the toxic algae in a news release on Thursday.

The US Army Corps of Engineers also reported blue-green algae on Pomme de Terre Lake in Hermitage, Missouri on Friday, June 3. This lake is around a two hour drive from Kansas City, but is located near popular vacation destinations around the Lake of the Ozarks.

Can I swim or operate a boat in lakes with blue-green algae?

No. Contact with this toxic algae can be very dangerous. In humans, it can cause symptoms including a skin rash, vomiting, diarrhea, fever, sore throat and headaches.

Skin contact alone is enough to make some people sick, so swimming is not advised. Boating is also risky because water spray can contain algae particles. If inhaled, these droplets can also lead to illness.

Pets are at even greater risk: KCUR reports that several Midwestern dogs have died in recent years after ingesting lake water that contained blue-green algae. Sometimes, algae is present in lake water before its colorful blooms are visible.

How can I tell which lakes have blue-green algae?

This KDHE map shows Kansas counties where blue-green algae has been found. However, the department only tests lakes where potential algal blooms have been reported by residents. That means any lake you visit could have unreported algae.

Algae blooms often look like bright green paint spilled into lake water or scum floating on the surface. Despite its name, this algae can be blue, green, brown or red in color.

“If the water appears suspicious or there is decaying algae on the shore, avoid contact and keep dogs away,” the KDHE wrote in its recent news release.

What should I do if I see or touch blue-green algae?

If you think you see a blue-green algae bloom, avoid coming into contact with the water. Keep pets from wading in the lake or drinking from it. In Kansas, report a suspected bloom here immediately. In Missouri, here’s what to do if you think the water may contain algae.

If you come into contact with lake water that may contain blue-green algae, the KDHE recommends washing the affected area with clean water as soon as possible. If a human or pet falls ill after exposure to lake water, even if no algae is visible, seek medical attention immediately. In Kansas, you can then report the incident here for the KDHE to investigate further.

Do you have more questions about recreation in and around Kansas City? Ask the Service Journalism team at kcq@kcstar.com.

Natalie Wallington
The Kansas City Star
Natalie Wallington was a reporter on The Star’s service journalism team with a focus on policy, labor, sustainability and local utilities from fall 2021 until early 2025. Her coverage of the region’s recycling system won a 2024 Feature Writing award from the Kansas Press Association.
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