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

Cyanobacteria, more commonly known as blue-green algae, has been identified in Henderson Lake. 

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.  

As always, park users are reminded to never drink or cook with untreated water from any recreational body of water including Henderson Lake, at any time.  

Cyanobacteria and algae are naturally occurring and often become visible when weather conditions are hot and calm. Cyanobacteria appears like a scum, grass clipping, fuzz or globs in the water and can be green, blue, brown or pinkish red, and often smells musty or grassy.  

People who come into contact with visible cyanobacteria or who ingest water containing cyanobacteria may experience skin irritation, rash, sore throat, sore eyes, swollen lips, fever, nausea and vomiting or diarrhea. Symptoms usually appear within one to three hours of contact and resolve within one to two days. 

Symptoms in children are often more pronounced but all humans are at risk of these symptoms. Exposure to the bacteria may be fatal to pets. 
  
The City of Lethbridge treats the lake monthly with beneficial bacteria that are designed to limit available nutrients that encourage blooms, as well as continuing to research preventative treatments for Henderson Lake. There are no treatments to stop or control cyanobacteria blooms. 

The City partners with Lethbridge Polytechnic to monitor the lake throughout the summer and find ways to manage the blooms.  

This advisory will remain in effect until further notice.  

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