by Alexis DeCorby
Saskatchewan Ministry of Agriculture
Algae and bacteria commonly occur in dugouts. Fortunately, there are several ways to control algae levels in your surface water. While not all algae types are toxic to livestock, blue-green algae (Cyanobacteria), can pose a risk. Algal blooms are not toxic to humans or animals. Blue-green algae’s name is misleading, because it is not algae, but a bacterium, known as Cyanobacteria. Common toxicity symptoms associated with blue-green algae include weakness, staggering, difficulty breathing and convulsions.
Development of Blue-Green Algae
Like most algae, blue-green algae thrives in stagnant water, such as dugouts. Light and nutrients (particularly phosphorus and nitrogen) are required for growth and we typically see algae blooms in the warm summer months. While not all blue-green algae produce a toxic bloom, it is impossible to tell which will be toxic visually. Always err on the side of caution if you believe blue-green algae is present.
Identifying Blue-Green Algae
Blue-green algae is characterized by its shiny, reflective appearance. In some cases, the dugout may look like pea soup, spilled paint floating on top or even varying colors of red or yellow. One way to determine if you have blue-green algae is to try to scoop some into your hand. If there are green particles (similar to grass clippings) that stick to your hand or slip through your fingers, it’s most likely blue-green algae. Filamentous algae will be long and stringy in comparison.
Treating Blue-Green Algae
The treatment method discussed is applicable for non-draining waterbodies such as dugouts, that are on private land. If the waterbody drains to adjacent areas or waterways, a permit for chemical control of aquatic nuisances is required from the Saskatchewan Ministry of Environment. Blue-green algae can be treated with any registered product, typically containing copper sulphate. Be sure to follow all label directions and application instructions. When the bloom dies, either by treatment or natural disturbance to the water, that is when it typically releases its toxins. It is recommended that producers wait 12 to 14 days before allowing livestock to consume any water from that source, to allow the toxins to dissipate.
Preventing Blue-Green Algae
The most cost effective method to controlling algae is prevention. Keeping water moving through aeration prevents warm water from building up near the top of the water body where algal blooms would form. Additionally, reducing or eliminating the amount of nutrients from runoff, fertilizer and livestock excrement from entering the dugout can limit the nutrients needed for algae growth. Having healthy riparian areas and excluding direct access by livestock to the source are just a few options to reduce or eliminate these nutrients.
Preventing, monitoring and treating algae in dugouts as needed is one component to keeping your water sources safe for livestock consumption. For more information on this topic, or any other livestock related questions, please contact your local livestock and feed extension specialist or call the Agriculture Knowledge Centre at 1-866-457-2377.