Cyanobacteria (Blue-Green Algae) advisory remains for Henderson Lake

The final long weekend of the summer is on the horizon. While many residents and visitors will flock to Henderson Lake Park, the City of Lethbridge is reminding everyone to be mindful of the Cyanobacteria advisory in effect for the lake.

More commonly known as blue-green algae, Cyanobacteria appears like a scum, grass clipping, fuzz or globs in the water. It can be green, blue, brown or pinkish red, and often smells musty or grassy.

Cyanobacteria are often born from hot, calm weather. This week’s rain and cooler temperatures have helped improve conditions. However, the expected heat during the long weekend and beyond might make things worse. 

Contact or ingestion of water containing cyanobacteria can result in skin irritation, rash, sore throat, sore eyes, swollen lips. Ingesting water containing Cyanobacteria may cause fever, nausea and vomiting or diarrhea. Symptoms usually appear within one to three hours and can resolve within one to two days. Symptoms in children are often more pronounced. Consuming the bacteria may be fatal to pets.

Residents and visitors are advised to take the following precautions:

• Avoid all contact with water experiencing Cyanobacteria blooms. If contact occurs, wash with tap water as soon as possible.  
• Do not allow pets or children to wade or swim in the lake.
• Do not feed whole fish or fish trimmings from this lake to your pets.
• Consider limiting human consumption of whole fish and fish trimmings from this lake as it is known that fish may store toxins in their liver.  

The City of Lethbridge treats the lake monthly, during the summer, with beneficial bacteria designed to limit available nutrients that encourage blooms. We are also continuing to research preventative treatments for Henderson Lake. Currently, there are no treatments to stop or control Cyanobacteria blooms.

In partnership with Lethbridge Polytechnic, the City monitors the lake throughout the summer.  

The advisory will remain in effect until further notice.

For Public Inquiries:
Call 311 | Monday to Friday, 8 a.m. to 4:30 p.m.