Managing Aquatic Plants in Farm Ponds

Aquatic vegetation can make a pond look messy, but plant growth in the water is not always a problem. In fact, some vegetation is good for most ponds. The issue is not whether plants are present. The issue is what kind of plants they are, how much of the pond they cover and what the landowner wants the pond to do.

A pond used mainly for fishing, livestock water or wildlife habitat can benefit from a moderate amount of aquatic vegetation. Plants help stabilize banks, reduce erosion, provide cover for fish and wildlife, improve water clarity and give insects, frogs and other small creatures a place to live. A pond with no vegetation at all may look clean, but it may not be as healthy or productive as it appears.

On the other hand, too much vegetation can interfere with fishing, watering livestock, swimming, irrigation or general enjoyment of the pond. Dense plant growth can make it difficult for fish to move and for anglers to cast. It can clog pumps or water lines. In some situations, it can also contribute to low oxygen problems, especially if large amounts of vegetation die and begin to decompose.

That is why pond management starts with the goal. A catfish production pond may need very little vegetation. A waterfowl pond may benefit from heavy coverage of certain plants. A typical farm or ranch pond used for livestock water and fishing usually does best with a middle ground. The right amount depends on the pond’s purpose.

The best time to prevent aquatic plant problems is when the pond is built or renovated. Many aquatic plants are limited by water depth. Shallow water allows sunlight to reach the bottom, which encourages plant growth. Deeper water reduces that opportunity. The Noble Research Institute article notes that many plant problems can be prevented by shaping most pond banks to a 20 to 25 percent slope down to at least four or five feet of depth.

That does not mean every pond can or should be rebuilt. Draining and reshaping an existing pond just to deal with weeds is usually not practical. But for landowners building a new pond, depth and bank slope are important decisions. Shallow edges may look gentle and easy to access, but they often become prime spots for unwanted plant growth. If livestock use the pond, fencing can help keep cattle from breaking down the banks and creating more shallow, muddy areas.

Once a pond has too much vegetation, there are usually three broad options: change the pond environment, use fish that eat plants or apply aquatic herbicides.

Changing the pond environment means making conditions less favorable for plant growth. Aquatic plants need sunlight and nutrients. Pond dyes can reduce sunlight penetration and limit the growth of submerged plants. Muddy water can have a similar effect, but muddy water is rarely the best solution. It may reduce plant growth, but it can also create water quality problems and lower fish production.

Fertilization is another tool sometimes used to encourage a phytoplankton bloom. A bloom can shade the pond bottom and tie up nutrients, limiting the growth of some submerged plants. This approach requires care. Too much fertility can create oxygen problems, fish stress or algae issues. Pond fertilization should not be a casual guess. Landowners considering this route should talk with a fisheries biologist before starting.

Grass carp are often used for aquatic vegetation control. These fish feed on many types of aquatic plants and can be useful in the right pond. They are not a perfect solution for every situation. Grass carp do not eat all plant species equally, and stocking too many can remove more vegetation than desired. Landowners should check state rules before stocking them, since regulations may apply.

Goldfish may help reduce filamentous algae in small ponds or stock tanks that do not contain larger predator fish. The Noble article notes that goldfish reduced filamentous algae to acceptable levels in metal stock tanks at Noble’s Red River Demonstration and Research Farm. This may be a practical option in some small watering systems, but it is not a general answer for larger ponds.

Herbicides are another tool, but they need to be used carefully. The first step is identifying the plant. Different herbicides control different types of vegetation. A product that works on algae may not work on cattails. A product labeled for floating plants may not control submerged weeds. Accurate identification can save money and reduce damage to plants that are not causing problems.

Labels matter. Only products labeled for aquatic use should be applied in or around ponds. The label will explain rates, timing, water-use restrictions and safety precautions. Some products may limit when water can be used for livestock, irrigation or recreation after treatment. Landowners should read and follow the label every time.

Timing also matters. Treating a pond after weeds have already taken over can create a new problem. When large amounts of vegetation die at once, decomposition uses oxygen from the water. If oxygen drops too low, fish can die. This risk is highest in hot weather because warm water holds less oxygen. In most cases, treating smaller areas or acting earlier in the growing season is safer than waiting until the pond is covered.

Not every plant needs to be removed. Some shoreline plants protect banks and provide habitat. Some submerged plants help small fish avoid predators. Some floating plants provide shade and cover. The goal should be control, not always elimination. A completely bare pond can be less useful for fish and wildlife.

Landowners should also look at what is feeding the plant growth. Runoff from fertilized fields, lawns, corrals or feeding areas can add nutrients to the pond. Livestock standing in the water can stir sediment, damage banks and contribute manure. Fixing those sources may help reduce future plant problems. Buffer strips of grass and vegetation around the pond can help filter runoff before it reaches the water.

Aquatic vegetation is easiest to manage when landowners pay attention early. Walk the pond edges during the growing season. Notice where plants are starting, how fast they are spreading and whether they are interfering with the pond’s use. Take photos and, if needed, collect a sample for identification. County Extension offices, fisheries biologists and conservation professionals can often help determine what plant is present and what control options make sense.

A pond is a living system. Plants, fish, insects, livestock, wildlife, water depth and nutrients all affect one another. Managing aquatic vegetation is not just about killing weeds. It is about keeping the pond useful, healthy and balanced.

For most farm and ranch ponds, some vegetation is a benefit. Too much becomes a problem. The key is knowing the difference and choosing the right tool before a small issue takes over the water.