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Solving Pond Problems

By Kerry W. Prather
Central Fishery District Biologist (retired)

Owning or managing a pond or lake can be really fun or really frustrating. Most private pond and lake-owners’ experiences probably fall somewhere in between. There can be problems associated with every aspect of a pond, even deciding what to call it. Is it a "pond" or a "lake"?

Let’s clarify this first. There is no absolute definition between the two. The one used most often is the "5-acre rule": Ponds are less than 5 acres while lakes are more than 5 acres. Since most ponds in Kentucky are less than an acre, we will use the term "pond" for the sake of this article.

Typically, ponds are also managed for fishing. Problems with smaller display pools for goldfish or aquatic plant gardens are a little different, but some of the following information may be helpful.

BUILD IT RIGHT FROM THE START

The best way to solve a pond problem is to avoid it in the first place. This means locating and building the pond in the right place. These precautions can prolong the life of the pond, avoid leakage, preserve the dam, protect your fish population, minimize aquatic plant problems, aid with fertility, and influence fish growth.

Ponds should have a ratio of at least 15 acres of land draining into the pond for every acre of water. If the ratio is significantly less, then there will be fewer nutrients (nitrates and phosphates) supplied to the pond. Nutrients power the fish population through plankton development. This means the water will be too clear, which causes problems with aquatic plants and supports fewer fish that grow slower.

If the ratio meets or exceeds this level, then these problems will be minimal and the fish population should do well. If the ratio is too excessive, then the life of the pond may be shortened by high sedimentation or the dam may be damaged by high water.

Fertility or land use activities in the watershed will also influence fish growth. If the watershed is forested, then fewer nutrients make it to the pond and fertilizer applications may be needed. Before you start building the pond, make sure you have contacted your local office of the Natural Resources Conservation Service (NRCS, formerly SCS). They have the soil maps that can help locate the best pond site.

POND STOCKING

So now you have a pond in a good location and you are ready to stock it with fish. This step is as important as the pond location. The best advice is to be patient and stock it correctly with the right combination of fish species.  KDFWR recommends largemouth bass, bluegill and channel catfish.  This combination of species is easy to manage and does well in all sizes and types of ponds.

Many newly constructed ponds are incorrectly and hurriedly stocked in the spring with all types of fish. The result may be slow fish growth, an unbalanced fish population and poor fishing. In most cases, it is best to stock in the fall with small fish from a fish supplier that will grow quickly in the new pond, particularly if the pond is allowed to age over the summer and develop a good population of invertebrates (insect larvae, crustaceans, worms, etc.) for the fish to eat.

If you inherited a pond that isn’t quite in line with the above recommendations, or maybe you unknowingly made some mistakes during the process, then the following information may be useful. The following problems are commonly received by KDFWR fishery biologists from pond-owners through telephone calls, e-mail, letters and personal contact.

LEAKS

If the leak is on the bottom of the pond, drain it, bring in and pack at least 12 inches of clay (possibly mixed with Bentonite) with a "sheep’s foot" roller. If the leak is in the dam, dig it out and repack with clay or you can try having a commercial grouting procedure done.

Slow reduction of water level due to evaporation is normal, but rapid water level loss down to a certain point is a sign of a leak. Prolonged leakage is usually evident by wet or seep areas somewhere below the dam. These usually have cattails, rushes or black willows growing in them.

Tips: Drought conditions can cause cracking, leakage and pond water levels to drop drastically. During pond construction, make sure the builder ties the clay core of the dam well into each bank. Bentonite should be mixed with dry soil to get best results; dumping Bentonite in the water in the area of the leak will probably not cure most leaks. To prevent future leaks, do not plant trees or allow trees to grow on the dam.

WRONG FISH SPECIES

Too many green sunfish, yellow bullhead catfish, crappie, common carp or small bluegill will require that the pond be renovated and restocked. This is done with Rotenone, a chemical specially formulated to kill fish. Pond owners must buy it from a commercial source.

Good fishing for largemouth bass or bluegill will be difficult as long as this situation exists. A healthy population of largemouth bass must be maintained to keep these species under control if they are present in low numbers. In some cases, such as too many bluegill, stocking largemouth bass may help.

Try to find out how the unwanted fish got there and control the source. Some may have invaded the pond from another pond above or below yours; they may have come from a bait release or someone who thought your pond needed these fish. If the source is not controllable, then you will have to deal with them through a strong bass population and removal by fishing.

Tips: The common notion that fish get into ponds from eggs stuck to bird’s legs has never been proven and is almost impossible. Do not go to a nearby stream to get fish for your pond. You may end up with species you do not want and you might introduce diseases or parasites.

TOO MANY LITTLE BLUEGILL

This is usually a result of improper stocking or not enough largemouth bass, typically because of over fishing or die-off. The quickest and surest solution is to renovate with Rotenone and start over. If this can’t be done, then try stocking 3- to 6-inch largemouth bass at a rate of 150 an acre for two to three years in a row. You might also want to add 8- to 11-inch channel catfish at 50 per acre.

Tip: Most bluegill only live 5 or 6 years; when fish are crowded, stunting occurs, and renovation may be the only solution.

TOO MANY LITTLE BASS

This may be a result of improper stocking, overprotection of bass, bluegill overharvest or limited bluegill spawning areas. Reduce the numbers of bass by fishing. A special management permit from KDFWR will be required to remove bass less than 12 inches. Also, while removing bass, you need to protect the bluegill. More bluegill will provide more food for the remaining bass.

Tip: This is the situation you want if you like extra large bluegill. Fewer bluegill mean bigger bluegill. However, if this situation exists for a number of years, there may be a few very large bass that have grown large by cannibalism.

"BUT I WANT TO STOCK CRAPPIE AND/OR HYBRID (BLUEGILL) SUNFISH TOO"

Don’t do it. Hybrid sunfish require special conditions with crowded predators to control the young of the hybrids. Hybrid sunfish are not sterile. Hybrids are produced by crossing a bluegill with a green sunfish—they will revert back to their original species.

Plan on stocking large numbers of predators such as bass and channel catfish to control the young if you want to have a hybrid sunfish pond. Even with these measures, you will probably have to renovate the pond every 5 to 6 years. Crappie must be kept under control by a strong largemouth bass population. Channel catfish will also help. If the numbers of these predators drop, then the crappie may overcome the population and become stunted.

Tip: If you must have crappie, use black crappie. They are less likely to overpopulate ponds.

"DO I NEED TO FERTILIZE MY POND?"

If your pond has an insufficient drainage and you can see 3 feet deep or more into the water throughout the summer, then you probably should fertilize. Fertilizing can reduce problem aquatic plant growth and improve fish growth by producing more plankton, which are microscopic plants and animals. Plankton actually clouds the water to shade out plants, but it also provides food for young fish.

Pond fertilization should be done at two-week intervals. Begin when water temperature reaches 60 degree, usually around the first of May, and continue until June 15. The easiest and most efficient fertilization method is with a liquid (7-14-7, 9-18-9 or similar formula) applied at the rate of one gallon an acre. Dilute with pond water during application. Apply fertilizer until water clarity reaches 2 feet. Stop applications when this is achieved. Resume if water starts to clear, but cease all applications by June 15.

Tip: Do not fertilize if you already have massive amounts of aquatic plants (underwater) as you may be boosting their growth; control this problem before fertilizing.

"DO I NEED TO ADD LIME?"

If you know the soil in the area around your pond is acidic or fertilizer applications haven’t worked, then you might need to add lime. To find out how much to apply, get a soil test done at a farm supply store or your county extension office. You want the lime application rate that would be used for an alfalfa field. Apply agricultural lime at the prescribed rate during the winter or early spring months. You can have the truck dump the lime in the pond drainage and let rain wash it in or you can apply it to the pond yourself. Applications may not need to be done every year afterward; try applying two or three years, then hold off a year or two to observe clarity. You may only have to apply every two or three years.

Tip: Check lime requirement of soil in a newly constructed pond and make applications on pond bottom before impoundment.

MUSKRATS

Heavy galvanized wire fencing can be placed a few feet above and below the surface to keep muskrats from digging holes. The dam needs the most protection. Other methods such as trapping and shooting can be used. First, however, check regulations and consult your local wildlife and boating officer. Muskrats are most active around sunset and sunrise. Letting your dog have access to the pond regularly will also help.

Tips: Muskrats move on wet nights and young disperse in the spring. You may get rid of your problem one day and have a new one the next week. Muskrats are the size of a large squirrel and have a long naked tail that moves from side to side when they swim. Muskrats often build large food mounds of soft vegetation for winter use in the pond. Don’t confuse muskrats with beavers. Beavers have large, flat naked tails and are the size of a small- to medium-size dog. Beavers feed on tree bark and build lodges of debarked trees and limbs.

TURTLES

Overall, these are not a danger to your fish population — they scavenge and eat very few live fish. Snapping turtles are a danger to young waterfowl. To remove turtles, bait heavy lines with chicken gizzards and place baited lines in the shallow water areas around the pond. Captured turtles can be eaten or relocated. Snapping turtles can be dangerous —stay well away from their head.

Tip: Smaller, hard-shell, or slider turtles can be captured with a trap. Make a trap place placing a box or barrel in your pond. Put a board across the top. Turtles will climb onto the board to bask in the sun, then fall into the box or barrel.

MUDDY WATER

If your pond stays muddy all the time and it is not because of rainfall, then the cause is either too many catfish keeping the sediments stirred up, or a fine clay soil around the pond. If the reason is catfish, then reduce their numbers by fishing or renovate with Rotenone. If the cause is the fine clay particles, then add organic material like hay.

Tip: Break open square hay bales and place them in the water every 10 or 15 feet around the shore. Clay particles will settle as the hay decomposes.

"DO I NEED TO FEED MY FISH?"

No, not even in a newly stocked pond. You can feed bluegill and channel catfish floating fish pellets. You can boost their growth and enjoy watching them eat — just don’t overfeed them.

TURNOVER AND FISH DIE-OFFS

True turnovers do not occur until late summer or fall when the pond is stratified (a deep layer of cold water with no oxygen). All ponds turn over, or mix, in the fall. Usually the pond turns a dark color and no fish die. During certain weather conditions, such as cloudy, windy, rainy or cool days, the turnover can occur too quickly and kill fish.

Fish die-off in the summer is a result of oxygen depletion. In this case, bacteria use oxygen faster than plankton can replace it.

In both cases, the fish populations are not a total loss and will eventually recover. Restocking may be necessary. In oxygen kills like these, the biggest fish will die first. Smaller fish will gulp air at the surface and may survive.

Tips: Mechanical aeration can help while these kills are in progress. Installation of an aeration system may be helpful if a die-off occurs regularly. Die-off in the spring of all fish species present, especially after a rain, is probably due to a toxin — usually a pesticide treatment. Do not make lawn pesticide applications in the pond drainage with rain in the forecast.

"DO I NEED TO ADD COVER FOR THE FISH?"

Fallen trees or brush piles along shore areas up to 5 feet deep are great fish covers — especially if there is no aquatic vegetation. Young fish need cover to hide from predators. Fish attractors can be placed every 50 to 100 feet.

GRUBS (WORMS) IN FISH

These are trematodes that use fish as part of their life cycle: fish, to fish-eating birds, to snail, then back to fish. The fish is usually a bluegill. Grubs are white, yellow or black. There is no cure. You can try to interrupt the cycle by treating the pond with copper sulfate to remove the snails — but this is hard to do, and you may kill some small fish. The presence of grubs will come and go. Just cut them out and cook the fish as usual. They can’t infect people anyway.

Tip: Redear sunfish (shellcracker) like to eat snails. Add 2- to 4-inch fish at a rate of 50 to 100 an acre to feed on snails.

AQUATIC VEGETATION

Owners should tolerate some plants in the pond. Plants provide cover for fish, add oxygen to the water and attract waterfowl. Control is suggested when plants cover more than 15-20 percent of a pond. Excessive plants can protect too many bluegill from bass predation, make fishing difficult and cause oxygen loss as the dead plants decay. Excessive shallow areas contribute to plant growth - your pond may need to be deepened.

There are four basic types of aquatic plants that require different chemical treatment and control. You’ll find these controls at farm supply stores, large nurseries or chemical suppliers. Treat about 1/3 of the pond at a time and avoid excessive treatments during the heat of the summer. Always make sure you know the kind of plant you are treating before applying any chemicals.

Tips: Drought conditions cause aquatic vegetation problems to be at their worst. Normal rainfall can reduce problems. Most chemicals cannot be applied until the water temperature is 60 degrees. These chemicals will not hurt your fish, but fish loss may occur because of oxygen loss if you kill too many plants at one time. Check labels on all chemicals for restrictions. If appearance is more important than fish production, commercial dyes for water plant control, such as Aquashade and Sky Blue Lake Dye, may be used if plants are in depths greater than 2 feet. Triploid grass carp (sterile) must be purchased from a KDFWR-certified dealer.

Chemical controls are available for algae. Triploid grass carp also may help solve algae problems in ponds.    Chemical controls are available for algae. Triploid grass carp also may help solve algae problems in ponds.
  1. Filamentous Algae ("pond scum"): Green cotton-like or hair-like floating mats that begin growth on the bottom. Treat with one of the following: Cutrine–Plus, K-TEA, Hydrothal 191 or copper sulfate. There are no restrictions for water use with these chemicals. Triploid grass carp, stocked at a rate of six to eight fish an acre, will eat it for the first year or two.
  2. Submerged ("seaweed" or "grass"): Visible growths underwater with stems, leaves and usually roots. These are pondweeds, naiads or "coontail." Some possible chemicals are Reward, Komeen, Aquathol, 2, 4-D, Weedtrine, Sonar, Avast!, Aquacide, Aquaquat and Hydrothal. Triploid grass carp will eat these. Stock fish at three to six an acre for gradual control or eight to 12 fish an acre for quicker control.
  3. Emerged (rooted under water but with stems and leaves out of the water): These are cattails, creeping water primrose, lilies, lotus, floating leaf pondweed, arrowhead and rushes. Possible chemicals are Rodeo, Reward, Aquacide, Aquaquat, 2, 4-D and Weedtrine-D. A surfactant may also be needed. Triploid grass carp are not a good control for these.
  4. Floating (plants float freely on the pond surface): Examples are duckweed and watermeal. These plants are very small, bright green and move from one end of the pond to the other on windy days. They are often confused with algae. These are the hardest and most expensive to control. Suggested chemicals are Sonar and Avast!. Triploid grass carp are not a good control for these.

These are a few of the problems pond owners may encounter. For more detailed information, order our Guide to the Management of Farm Ponds in Kentucky. For more information, call (800) 858-1549 on weekdays.