Livestock producers are being urged to monitor water quality closely as persistent dry summer conditions intensify contamination risks in ponds, wells, and dugouts, according to Manitoba Agriculture specialists.

"What we're left with is some of those salts and minerals," said Elizabeth Nernberg, forage and livestock specialist at Manitoba Agriculture. "If the water wasn't great quality to begin with, as the summer goes on... the poor water's going to get worse."

As evaporation reduces water levels and livestock water demand increases, salts, sulfates, and blue-green algae become more concentrated-posing serious health risks to cattle.

Water makes up 50 to 80 percent of an animal's live weight and is the most critical nutrient, Nernberg emphasized during a webinar on August 20. A cow-calf pair can drink about 15 gallons per day, making water quality pivotal to livestock health and productivity.

Blue-Green Algae: A Hidden Threat

One of the most alarming risks is the rise in blue-green algae, which thrives in shallow, sunlit, nutrient-rich water. Known for its paint-like appearance and slimy texture, this algae produces bacterial toxins when it dies-especially when blown by wind to shoreline areas.

"These toxins remain dangerous for up to two weeks after the bloom dies off," Manitoba Agriculture warns.

However, not all surface growth is harmful. Duckweed, often confused with algae, is a beneficial aquatic plant that can help reduce nutrient levels and block sunlight, discouraging algae growth.

Water Testing: An Annual Must

A recent provincial survey across 39 Manitoba pastures found that fenced dugouts generally had better water quality than wells. Still, total dissolved solids remained below 3,000 mg/L, a commonly cited threshold for livestock safety.

Nernberg advises producers to test water at least annually, and more frequently if they observe changes in taste, odor, clarity, or livestock performance.

"Do not rely on past analysis," she cautions. "Analyzing your water is important. It can change from year to year and even within a season."

Best Practices for Prevention and Control

Preventing algae and contaminant buildup requires a multi-layered strategy:

Control nutrient runoff from nearby cultivated fields.

Exclude livestock from direct access to water bodies.

Install aeration systems to reduce stagnant conditions.

Use mechanical methods first-like hand pulling or chaining aquatic weeds.

When necessary, chemical treatments must follow strict label instructions. For example, water treated with Reward herbicide should not be consumed by livestock for at least 24 hours post-treatment.

Nernberg also warns against overreliance on chemical solutions. Some algae species are becoming resistant to copper sulfate, a common treatment for pond systems.

Design and Vegetation Management

Proper dugout construction and vegetation management can mitigate risks:

Maintain grass buffers of at least 10 meters around water sources.

Keep trees at least 50 meters away to prevent organic matter accumulation.

Prevent nutrient-rich runoff from fields or feedlots.

These steps help maintain oxygen levels, reduce nutrient loading, and create a healthier water environment throughout the grazing season.