Blue-green algae, scientifically known as cyanobacteria, are microscopic organisms that can form harmful blooms in farm water sources such as dugouts. These blooms are most likely to occur during hot weather, especially when temperatures exceed 25°C (77°F), and they pose a serious risk to livestock health.
Identifying Blue-Green Algae
Blue-green algae typically appear as a blue-green scum, thick pea soup, or floating grass clippings on the water’s surface. However, not all green growths are harmful—if the substance can be picked up as a solid mass, it is likely not blue-green algae. When the presence of cyanobacteria is suspected, it is important to consult a water specialist for proper identification and to remove livestock from the water source immediately.
Health Risks to Cattle
If ingested, toxins produced by blue-green algae can cause severe organ damage or even death in livestock. Other farm hazards, such as toxic plants like water hemlock or improperly stored items like batteries, can also pose poisoning risks. If the cause of illness in cattle is unclear, veterinary advice should be sought.
Treatment and Management
If confirmed, blue-green algae in a dugout can be treated with a copper-based product registered for agricultural use. However, once treated, livestock should be kept away from the water for up to a month. Copper treatment can rupture algal cells, releasing toxins into the water all at once. During this period, the water must be allowed time for the toxins to naturally degrade.
Follow-up treatments with aluminum sulfate or hydrated lime can help remove excess nutrients from the water and prevent further algal growth. In some cases, these treatments may be more effective than copper alone.
Prevention Strategies
Preventative measures play a key role in reducing the risk of algae blooms. Constructing deeper dugouts with steep, stable slopes can help lower water temperatures, making conditions less favorable for cyanobacteria. It’s also important to prevent nutrient runoff—key drivers of algal growth—from entering the dugout. Techniques such as buffer strips, grassed waterways, culvert controls, and off-site watering systems can help reduce nutrient loading.
Dugouts should be built away from natural waterways to avoid sediment and nutrient buildup, which can reduce water depth and quality over time. Aeration systems and dye packets may also be used to limit photosynthesis, further discouraging algal growth. However, no single solution is guaranteed—often, a combination of measures is most effective.
Monitoring and Safety
Blue-green algae can shift within the water column and accumulate in concentrated areas, particularly when pushed by wind. This makes certain spots in the dugout more dangerous for cattle. Regular monitoring, including inspecting deeper sections of the water, is essential. For safety, it’s advised to inspect dugouts with another person present and to carry a rope and flotation device.
Proper identification, timely intervention, and long-term management can help ensure water safety for livestock and reduce the risks posed by blue-green algae on farms.
