Alberta Health Services has issued a public health advisory asking Albertans to avoid Matchayaw (Devil’s) Lake — about 60 kilometres west of Edmonton — after a cyanobacterial (blue‑green algal) bloom and/or toxins were identified in the water.
What AHS is advising
The agency’s notice, posted Tuesday, lays out a string of precautions aimed at reducing the risk of illness for people and pets who may come into contact with the water or washed‑up material along the shore.
- Do not swim or wade in areas where cyanobacterial blooms are visible.
- Avoid all contact with visible blooms in the water or material washed up on shore.
- Do not drink or use lake water for cooking; untreated lake water may contain toxins and boiling will not remove them.
- Avoid feeding whole fish or fish trimmings from the lake to pets; toxins can be concentrated in fish organs such as the liver.
- Keep pets away from the water, and do not allow them to swim where blooms are present.
- If contact occurs, wash with clean tap water as soon as possible.
Health effects and vulnerable groups
According to AHS, cyanobacteria are naturally occurring organisms. Large growths, called blooms, are more common in warm weather. They can appear in a range of colours and textures — blue‑green, greenish‑brown, brown, pink or red — and may look like scum, streaks, grass clippings, fuzz balls, paint or pea soup. Blooms often have a musty or grassy smell.
“People who come in contact with a cyanobacterial bloom or who ingest water containing cyanobacteria may experience skin irritation, rash, sore throat, sore red eyes, swollen lips, fever, nausea and vomiting and/or diarrhea.”
AHS says symptoms can appear within one to three hours of exposure and usually resolve in one to two days. The agency notes that children’s symptoms are often more pronounced, but warns people of all ages can be affected. The advisory also cautions that exposure may be fatal to pets.
Advice for anglers and pet owners
Anglers are warned not to eat whole fish or fish trimmings from Matchayaw (Devil’s) Lake because toxins can be stored in fish livers and other organs. AHS states fish fillets contain fewer toxins and are generally safer to eat, but the advisory underlines that caution is warranted.
Pet owners are reminded not to let animals swim in or drink from areas where blooms are visible and to avoid feeding pets any whole fish or trimmings taken from the lake.
| Risk | Recommended action |
|---|---|
| Human exposure (swimming, wading) | Avoid contact; wash with tap water if contact occurs |
| Ingesting lake water | Do not drink or use for cooking (boiling will not remove toxins) |
| Pets | Keep away from water; do not feed whole fish/trimmings |
Reporting and further information
AHS urges anyone who suspects health problems related to cyanobacteria, or who has other health concerns after possible exposure, to contact Health Link by dialing 811. Residents are also reminded that untreated water from any natural source should never be consumed.
For Edmontonians, the advisory is a reminder that warm summer weather increases the likelihood of cyanobacterial blooms in regional lakes and that simple precautions can reduce risks to families, anglers and pets. As the agency notes, visual signs and odour are common indicators; when in doubt, avoid contact and seek tap water for washing.
The advisory does not provide timelines for when the lake will be re‑classified as safe. AHS typically issues updates as monitoring results change; residents and visitors planning to use area lakes should check for the latest notices before travelling.
