Frequently Asked Farm Pond Questions

August 2018


How do I get rid of pond weeds?
Bring or send a sample of the problem plant or a close-up photo to the local county Extension office for identification. How much of the pond is covered? A map view sketch of the pond can be useful. Are there large shallow areas filled with plants? Are there sources of nutrients that drain into the pond such as fertilizer for lawns, animal manure, etc.? Is there a thick layer of black smelly organic matter on the bottom of the pond? This can release nutrients promoting excess plant growth. Pond plants, in moderation, have major benefits — shoreline plants protect against bank erosion by waves. Submerged and floating plants often prevent growth of algae – either filamentous algae or excess planktonic algae – by competing for light and nutrients. Pond plants work to keep water clear and prevent muddiness. With all these factors in mind, use of herbicides and other management steps can be considered. There is no general-purpose aquatic herbicide. The identity of the problem plant, the uses of the pond and other factors must be considered in selecting a suitable herbicide. Herbicides are not a permanent solution – if factors favoring excess growth of aquatic plants are present, they typically return.

How do I clear up a muddy pond?
There are no guaranteed ways to permanently clear muddiness. That said, underlying factors need to be considered. Check the watershed for active erosion. Look for bare soil from construction, county roads, eroding bar ditches and overgrazing. Unless and until these can be corrected, the pond will likely remain muddy. Collect a jar of water and allow it to sit for one week on a shelf. If the water does not clear significantly, something is keeping the pond stirred up and re-suspending the clay. Are there common carp or other bottom feeding fish in large enough numbers to stir the bottom? Is the pond exposed to wind? If so, is it feasible to establish a windbreak? If erosion in the watershed is controlled and the jar of water does not clear, consider old hay. Add two small square bales per surface acre. More details and alternative methods can be found in NREM 9206, Common Pond Problems.

Why are my fish dead?
Fish kills happen one of two ways: all at once or slowly over several weeks. How quickly are the mortalities happening? A sudden large number of dead fish usually is due to a decline in dissolved oxygen levels. This happens when a large amount of plants die and decompose or when ponds turn over, typically in the fall. Less often, a toxic substance can be the cause of a fish die-off. A gradual die-off, with some fish showing unusual swimming patterns or behavior is a sign of a disease problem. The fish kill section of NREM 9206, Common Pond Problems, offers a series of questions to help narrow down the possible cause of a fish kill.

Are livestock and pets safe after a fish kill?
To be on the safe side, keep livestock and pets away from the pond in the short term. If you cannot discover other likely causes and valuable animals are at risk, consider contacting the Animal Disease Diagnostic Lab (405 744-6623) to see about having the water checked for toxic species of algae. If it is a toxic algae, practical advice is given in NREM 9213, Toxic Blue-Green Algal Blooms.

How do I fix a pond that is leaking?
There are many possible reasons why a pond may not hold water or fill. Many pond owners jump to the conclusion that the dam is the problem – this is often incorrect. Consider leaks in the basin (the “bowl” that fills with water) or an overly small area of land that slopes toward the pond basin (the watershed). Ponds that have never held water likely suffer from sandy soil, rock outcroppings or gravel or sand layers that are allowing water to leak out of the basin. Alternatively, there may be issues with leaks under or through the dam. Limited leakage through or under the dam is normal in some ponds. Another explanation for the inability to fill is that the watershed is too small to generate adequate runoff. Ponds that used to hold water, but now do not may have a leak through or under the dam. Some pond dams do leak slowly without being at risk of failure. Fast leaks or flows are a serious warning flag of internal erosion that may quickly lead to a dam failure. We can only narrow down the possibilities and suggest possible fixes: there are no guaranteed solutions. Bentonite clay is often used but is messy, expensive and labor-intensive to apply properly. Powdered bentonite is only recommended when a pond is empty – it should be tilled into the soil. If you must apply bentonite through standing water, the granular form is needed. Pond owners with these problems should visit with the Natural Resource Conservation Service (NRCS) – they are the local pond design and repair experts.

How do I get rid of turtles?
“Sliders”, including the red-ear, are the most common turtle causing complaints from pond owners. Sliders bask in the sun on logs and can be trapped using teeter traps – see the illustration in NREM-9206, Common Pond Problems. Sliders do present an unattractive appearance when overabundant and will consume fish feed intended for fish. If sliders are eating fish held on stringers, consider holding caught fish in fish baskets. Snapping turtles, or snappers, are less often a problem. They can be trapped using either submerged hoop nets or an extra-large snap trap attached to a dock leg or upright stake. Both traps should be baited with a piece of tough meat.

Should I cut down the trees on my dam?
Young trees and shrubs should be removed each year, either mechanically or by herbicide. If allowed to grow to a large size their roots can allow leakage, leading to internal erosion and failure of the dam. The larger the trees and taller the dam, the greater the risk is that cutting trees will accelerate a dam failure. In situations where a dam failure poses a significant risk, seek expert help from the Natural Resource Conservation Service (NRCS). It is especially important to seek expert help from pond engineers and technicians at the NRCS, if your pond dam impounds a large quantity of water and buildings, roads or people below the dam are at risk if it should fail. In cases where it is judged safe to remove trees, root wads may need to be grubbed out and the hole refilled. Add 6 to 10 inches of clay soil, hand-tamp thoroughly and repeat until the hole is completely refilled.

My fish have worms. How do I get rid of them?
Yellow grubs are the most common fish parasite matching the description worm. About the size of a large pinhead, they are found throughout the muscle or sometimes just under the skin on the body or fins. They are not harmful to humans. There is no practical, approved deworming medicine or other quick and easy fix. Instead, try to reduce or eliminate the other two hosts of the parasite: fish-eating birds and aquatic snails. Without a way to complete the lifecycle, they die in the fish and disappear. A copper sulfate application is sometimes successful in reducing or eliminating aquatic snails. If submerged aquatic plants are overabundant, use of herbicide can be considered to reduce aquatic plants that are used by snails for cover and food. See the E-832, Extension Agents’ Handbook of Insect, Plant Disease and Weed Control for advice on using copper sulfate and other herbicides in ponds. Eliminating roosts used by fish-eating birds is sometimes beneficial. Scare methods can also be used to reduce the number of fish-eating birds using a pond. Red-eared sunfish are a snail-eating fish that can reduce snail populations. More information is in NREM-9206, Common Pond Problems.

 

Marley Beem
Assistant Extension Specialist

DASNR Extension Research CASNR
OCES  Contact
OCES
139 Agricultural Hall
Oklahoma State University
Stillwater, OK 74078
OKLAHOMA STATE UNIVERSITY