There can be a deadly danger in your dugout

Toxins from blue-green algae can be fatal if ingested by livestock, but you can reduce the risk

Toxins produced by blue-green algae can cause organ damage or even death if ingested by livestock or pets.
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It’s the time of year to keep watch for blue-green algae.

“Blue-green algae is actually cyanobacteria, and can produce toxins that can be very dangerous,” said Shawn Elgert, a provincial agricultural water engineer. “It can cause organ damage or even death if ingested by livestock or pets. If you are trying to determine the cause of poisoning, there are other potential toxins on the farm that can also cause damage to cattle such as poisonous plants. An example of this is water hemlock.”

The first important step is to identify the type of growth, he said.

“Blue-green algae can look like blue-green scum, pea soup, or grass clippings suspended in the water. You should start watching for it when the temperatures increase.”

If blue-green algae is suspected in a dugout, be cautious.

“You should contact a water specialist to diagnose the growth to determine if it is potentially a toxic growth,” said Elgert. “You should also remove your livestock from the water source in the interim and prevent them from accessing it. One rule of thumb is that if you can grab it as a solid mass in your hand, that is not blue-green algae.”

There is a copper product registered for use on blue-green algae in farm dugouts.

“Once you treat it, consumption should be restricted for up to a month. The use of copper will break the cells open and release the toxins, if present, into the water all at once. So it’s important that you stop using the water during this time so the toxins can degrade. You can follow up with aluminum sulphate and/or hydrated lime treatments afterwards to remove the nutrients from the water to prevent regrowth.”

There are also preventive measures that can be taken.

“Temperature is an important factor in the growth of blue-green algae, so a deeper dugout with slopes that are not too flat would help make the dugout water cooler.

For information on reducing nutrients — which are required for growth of blue-green algae — from entering a dugout, see the Quality Farm Dugouts manual (go to and search for ‘quality dugout’).

“Buffer strips and grassed waterways are examples of how you can reduce nutrients,” said Elgert. “Dugouts should not be built in the waterway as sediments can bring more nutrients into the dugout and depth can be lost quickly. Aeration of the dugout can also help improve the water quality. Also, a dye packet can be thrown into the dugout to help prevent photosynthesis from occurring, thereby reducing the growth of blue-green algae. However, one action alone may not be enough to prevent growth.”

Wind can push the blue-green algae into highly concentrated pockets where the risk of harm is higher.

“Since blue-green algae can rise or fall in the water column, inspection of the dugout should include peering into the deeper part of the water. Always be safe around the dugout by going along with another person and have a rope with a flotation device attached.”

For more information or assistance, contact an Alberta Agriculture water specialist at 310-FARM (3276).

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