Photo: Warm, nutrient-rich dugout water can support cyanobacteria that may poison livestock. Producers should restrict access to suspicious water until the growth has been identified. Photo credit: Unsplash

Alberta livestock producers are being advised to monitor farm dugouts for cyanobacteria, commonly called blue-green algae, because contaminated water can cause serious illness or death in animals.

The bacteria can produce toxins that are dangerous to livestock, pets and people, according to Alberta Agriculture and Irrigation.

Cyanobacteria may appear as blue-green surface scum, pea-soup-like water, fine material resembling grass clippings or jelly-like nodules that turn to slime when crushed.

Growth can begin when water temperatures are below 20 C, but the bacteria reproduce more quickly as the water becomes warmer. Nutrient-rich water and sunlight can also contribute to blooms.

Wind can push the bacteria toward one part of a dugout, creating a concentrated pocket that may be more dangerous than the surrounding water. Cyanobacteria can also move up and down through the water column, making a quick surface inspection unreliable.

Producers who suspect a bloom should immediately move livestock away from the dugout and prevent access until the growth has been identified. Alberta Agriculture recommends contacting a water specialist for assistance and consulting a veterinarian when poisoning is suspected.

Other farm hazards, including water hemlock and accidental exposure to contaminants, can produce symptoms that may be mistaken for cyanobacteria poisoning.

A growth that can be lifted from the water as a solid mass is generally not cyanobacteria. However, producers are advised to treat unidentified growth cautiously rather than relying only on its appearance.

Copper-based products registered for use in farm dugouts can control confirmed cyanobacteria. Treatment breaks open the bacterial cells, which can release toxins into the water.

Livestock may need to be kept away from treated water for up to one month while sunlight breaks down the toxins. The required period can vary depending on the severity of the bloom and the amount of sunlight reaching the water.

Aluminum sulfate and hydrated lime may be used after treatment to remove nutrients and reduce the chance of another bloom.

Long-term prevention includes maintaining deeper dugouts with steeper slopes, limiting sediment buildup and reducing the flow of nutrients into the water. Buffer strips, grassed waterways, culvert controls and off-site watering systems can help protect water quality.

Aeration and pond dyes may also reduce conditions that support cyanobacteria, although the province cautions that no single measure will prevent every bloom.

Producers can contact an Alberta Agriculture and Irrigation water specialist through 310-FARM for help identifying suspected cyanobacteria or managing a farm water source.