Is the Pond Safe for Livestock?

By OKFR Staff

During the hottest part of summer, a farm pond can look like a welcome source of water. Cattle may be standing belly-deep along the bank, and the pond may still hold enough water to seem dependable. Looks alone won’t tell you whether that water is safe.

Hot weather, limited rainfall and falling pond levels can create water-quality problems. As water evaporates, salts, minerals, nutrients and other substances become more concentrated. Warm, still water can also encourage blue-green algae, and some forms can produce toxins capable of killing livestock.

Producers sometimes treat water as an afterthought compared to grass, hay and supplemental feed. Livestock need a dependable supply of clean water to maintain feed intake, regulate body temperature and support production. Poor-quality water can reduce consumption and performance even when it does not cause obvious poisoning.

A pond that has watered cattle for years is not safe under every set of conditions. Pay particular attention during drought, extreme heat or any period when the water level drops significantly.

Watch the Water and the Livestock

One of the most serious late-summer concerns is a bloom of cyanobacteria, commonly called blue-green algae. These organisms live naturally in many bodies of water, and most do not produce dangerous toxins. The risk rises when certain toxin-producing species multiply rapidly under favorable conditions.

According to Oklahoma State University Extension, toxic blue-green algal blooms typically develop in standing water after periods of hot, dry, calm weather. Nutrients such as nitrogen and phosphorus can fuel excessive growth. Those nutrients may reach a pond through manure, fertilizer runoff, soil erosion and decaying vegetation.

A suspicious bloom may turn the water bright green, blue-green, pea-soup green or even brownish. Scum, foam or mats may collect along the shoreline, particularly where the wind pushes floating material into one area. Some blooms look like spilled paint.

Not every green pond is poisonous. Common aquatic plants and harmless algae can also change the color or surface of the water. You usually cannot tell whether a bloom is toxic by looking at it, and a pond can contain toxin-producing cyanobacteria without showing every commonly described warning sign.

Keep livestock, horses, pets and people away from water that has an unusual color, heavy surface scum, a bad odor or unexplained dead fish or wildlife nearby. Do not let livestock drink from another part of the same pond on the assumption that the water is safe there. Wind can move a bloom, and toxin levels may vary across the pond.

Blue-green algae can produce toxins that affect the nervous system or liver. Depending on the toxin and the amount consumed, affected animals may develop weakness, staggering, difficulty breathing, tremors, convulsions, diarrhea or collapse. In severe cases, owners find animals dead near the water before realizing anything is wrong. Treatment often fails, which makes prevention especially important.

Treat any suspected poisoning as an emergency. Move the herd away from the water source without driving or stressing animals that may already be affected. Provide another clean water supply and contact a veterinarian immediately. Your county Extension office can also help you determine where and how to submit a water sample.

Blue-green algae is not the only potential problem. Pond water may contain elevated levels of dissolved salts, sulfates, nitrates, bacteria or other contaminants. Runoff can carry manure, fertilizer, pesticides and organic matter into the pond. Low water levels make some of these problems worse because the remaining water grows more concentrated.

Water with excessive dissolved solids may taste bitter or salty, so animals drink less of it. Depending on the substances involved and their concentrations, poor-quality water may contribute to diarrhea, reduced feed intake, poor weight gain or other health concerns. Young animals and livestock that are not used to the water may be more vulnerable.

Watch the cattle themselves, too. Are they reluctant to drink? Are they crowding around a different water source? Has feed intake or weight gain dropped without an obvious explanation? Are several animals having digestive problems? Changes across multiple animals can be an early clue that you need to look at the feed or water.

OSU Extension recommends collecting a representative sample and submitting it for a livestock water test whenever you suspect a water supply is harming animal health or performance. A standard livestock water test covers several characteristics, but blue-green algae can require different sampling and testing procedures. Contact the laboratory or county Extension office before collecting the sample so you take it from the right location, use the proper container and handle it correctly.

Reduce Problems Before They Develop

Good pond management cannot eliminate every water-quality problem, but it can lower the risk. One of the most effective steps is limiting the manure, soil and nutrients that enter the water.

Cattle with unrestricted access to an entire pond can damage the banks, muddy the water and deposit large amounts of manure in or near it. Hoof traffic strips vegetation and speeds erosion. Sediment fills the pond over time, while manure supplies nutrients that can encourage excessive algae growth.

Where practical, fence livestock away from most of the pond and provide a limited-access watering point. Another option is piping water to a trough below the dam or elsewhere in the pasture. OSU notes that reducing cattle manure in the pond can reduce the conditions that favor toxic algae and make the water more palatable.

A vegetated buffer around the pond can slow runoff and trap soil and nutrients before they reach the water. Apply fertilizer and manure carefully in the watershed, particularly before heavy rain, and do not let large amounts of hay, feed or organic debris pile up at the water’s edge.

Alternative watering systems need maintenance, too. Check troughs for algae, manure, drowned animals and other contamination. Install wildlife escape ramps in tanks so birds and small animals can climb out instead of drowning and fouling the water.

Be cautious about treating a pond on your own. Some owners use copper sulfate and other algaecides for algae control, but improper treatment can create new problems. Killing a large amount of algae or aquatic vegetation at once can deplete dissolved oxygen as the material decomposes, which can lead to a fish kill. Treatment may also release toxins from affected cyanobacteria into the water. Base any chemical application on proper identification and professional recommendations, not guesswork.

Livestock should always have enough water for the weather, their size and their stage of production. Demand rises sharply in hot weather, and a pond that barely meets the herd’s needs in spring may fall short in August. Check the source regularly instead of waiting for cattle to gather around a muddy shoreline.

Ponds can fool you. Crystal-clear water isn’t always safe, and a green pond doesn’t always mean toxic algae. Regular observation, testing and prevention are the best ways to keep a pond safe for your herd.