See event listings and more articles in this edition of Agri-News: June 17, 2026 issue
What is commonly called blue‑green algae is actually cyanobacteria, and under the right conditions it can produce toxins that are dangerous to livestock, pets and people. In the worst cases, it can cause organ damage or death if animals drink contaminated water.
“There are other toxins on the farm that can cause damage as well, things like water hemlock or even accidental ingestion of contaminants, so if you are dealing with a suspected poisoning, a veterinarian should be part of the conversation,” says Shawn Elgert, agricultural water engineer with the Alberta government.
Elgert says the first step is knowing what you are looking at. Cyanobacteria can look like:
- blue‑green scum along the surface
- water that looks like pea soup
- fine material suspended in the water, like grass clippings
- jelly-like nodules that can be squished into slime
“Even though cyanobacteria can start growing at a water temperature lower than 20°C, you can start monitoring it at that temperature, as the warmer it gets, the more the growth rate increases. One simple rule of thumb: If you can scoop it up as a solid mass, it is not cyanobacteria. If you do suspect cyanobacteria, act cautiously. It is better to be cautious than deal with a livestock loss.”
- Contact a water specialist to assist with identification.
- Remove livestock from the dugout immediately.
- Prevent access until you know what you are dealing with.
Also keep in mind that wind can push cyanobacteria into concentrated pockets and become highly toxic.
If cyanobacteria is confirmed, treatment is possible, but timing and management matter. Elgert says copper-based products (registered for dugouts) can control the bloom; however, copper breaks cells open, releasing any toxins into the water all at once. Because of that, do not let livestock drink treated water for up to a month, depending on the intensity of sunlight. He adds that the toxins will eventually break down under sunlight.
In many cases, follow-up treatments such as aluminum sulfate (alum) and hydrated lime can help remove nutrients and reduce the chance of regrowth. In some situations, these approaches are more effective than relying on copper alone.
Prevention – your best tool
Cyanobacteria need warm, nutrient-rich water. Management focuses on limiting those conditions.
Dugout design
- Build deeper dugouts with steeper slopes to keep water cooler.
- Avoid sediment buildup that reduces depth over time.
- Don’t locate dugouts directly in waterways where runoff carries nutrients in.
Keep nutrients out
- Maintain buffer strips.
- Use grassed waterways.
- Install culvert controls where needed.
- Install off-site watering systems to protect the dugout.
Elgert adds that there are other tools that can help prevent cyanobacteria, including aeration, which can improve overall water quality, and dyes, which can reduce sunlight penetration and limit growth.
“No single method is a silver bullet. Layering these approaches gives the best results,” says Elgert.
In addition to these management practices, Elgert says it is important to inspect the dugout, while keeping safety top of mind. Cyanobacteria can move up and down in the water column, so a quick glance is not enough. Look across the entire dugout and check deeper water where possible. Avoid working alone around dugouts and carry a rope with a flotation device if you are inspecting close to the edge.
Refer to the Quality farm dugouts manual for further information.
For more information or assistance, contact an Alberta Agriculture and Irrigation water specialist at 310-FARM (3276).
For more information, see:
Contact
Connect with a water specialist for more information:
Phone: 310-FARM (3276)
Sign up for Agri-News
Start every Monday with the week’s top agricultural stories and latest updates.
Read about all things agriculture at Alberta.ca/agri-news