Your Guide to Farm Pond Design
The Importance of Farm Pond Maintenance
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By Crow Miller – You can create an effective farm pond design, whether you live on a few acres or 500. The water from a small stream is sufficient. A fraction of the flow from a large stream or river can be diverted, without depreciation or serious reduction in irrigation volume. Except in dry country, good grading and cover-cropping of the local watershed will provide enough water to keep a pond filled. Nearby springs sometimes can be piped, or tapped upon excavating into a valley or hillside. Even a well that delivers 20 gallons or more per minute may be used to deliver supplementary water to a farm pond.
The banks of a good farm pond design should be grassy and trimmed to the water’s edge. The surface should be clean, rippling where fish have surfaced to catch an insect, and move gently to the overflow. It should serve as a pleasant welcome to fishermen and swimmers of all ages.
The key to a fine farm pond design is proper initial construction. The first consideration is water volume and availability. Do not attempt to build a second Lake Mead if you depend upon a small stream, springs or runoff. A skilled excavator can advise you on the practical area to consider. If, on the other hand, the supply of water is unlimited, you may plan on as large a farm pond design as is physically and economically practical.
Grading should compromise as much as possible with the original slopes. Especially avoid extreme drops where soil erosion can occur around the banks or on the lower side of the dam. It is not advisable to build a large farm pond if you have to create a high and steep artificial earthwork. Conversely, a good grading plan avoids creating areas of shallow water or gradually descending banks, especially likely to occur near the upper end of the farm pond. Banks should be fairly sharp, between 45 and 30 degrees, providing for rapid drop-off to water at least several feet deep to avoid warm and stagnant areas.
Don’t go for fancy curves and backwaters, since such places slow water movement, encourage algae growth and poor oxygenation for fish. If you want an island in the middle of your farm pond design, make sure the banks are fairly steep. The best over-all shape is approximately tear-drop end at the dam somewhat flattened across the inner surface of the breastwork.
An alternative is the nearly round farm pond design, where natural grades require a dam in the form of a crescent, sweeping back a considerable distance along either side to reach higher ground. Round farm pond designs are particularly appropriate if spring fed from below the surface, or if located at the head of a swale that receives surface runoff from a surrounding amphitheater of wooded and sodded areas.
Too many dams have tops that are too narrow. The finished top of any dam should never be less than 15 feet wide, allowing for a 20-degree inside slope, and a 30-degree outside slope. The edges will become rounded in time, reducing top width, and some settling and erosion will take place before a good sod is established and muskrats may start tunneling.
The best control of muskrats is never to let them get started. Fairly steep banks, clean mowing and no vegetation standing in the water are help in discouraging them. When the farm pond design is shaped, heavy galvanized turkey wire, one-by-two-inch mesh, can be laid all around the banks, from a point just above the anticipated water level to several feet below. A muskrat seldom can overcome this protection. If tunnels are found, it is time to start trapping (in season and according to local law).
Where your farm pond design is in a stream valley, the main watercourse should be diverted around the side, in its own channel, or in a newly created bypass. At a point slightly above the upper end of the farm pond design, the stream should be slowed and widened by building a loose stone or masonry dam, to form a small pool from which a pipe carries water to the farm pond. In times of flooding, most of the stream water flows harmlessly through and over the dam; if the force of water reaching the pipe becomes too great, a cover can be temporarily placed over the streamward end to prevent debris from entering.
The best type of outflow is a trickle tube: a vertical standpipe, connected with a tee to a horizontal pipe under the dam. The open end of the tee should be fitted with a wood plug, having a ring screwed into it and a chain attached, so that the plug can be yanked out if ever necessary to drain the farm pond. Mechanical valves, with long-handled controls, are generally a nuisance, becoming rusted fast or clogged with debris. In laying the horizontal pipe, concrete or metal collars are placed every few feet, to prevent seepage loss. An alternative outflow, especially in localities where rainfall is moderate and sudden heavy discharge from the farm pond is not likely to occur, is a depressed area toward one end of the dam, or along one side near the deep end. Such an overflow point should be kept well sodded, and a few stones scattered about will help break up any rush of water and resultant channeling. Concrete spillways are not generally advisable, since there is a tendency for water to undermine and cause serious damage, resulting in a lowering of the pond level.
Farm Pond: Design the Bottom
In some localities, especially where water volume is limited, the natural soil may not be impervious enough to form a suitable pond bottom. There are several solutions to this problem. Often, a bed of clay will be exposed during excavations which can be stockpiled, then graded over the shaped surface of the bottom and packed into place by the bulldozer treads. Clay can usually be purchased nearby, if necessary. In extreme situations of leakage, bentonite can be purchased and spread over the bottom, either before or after filling, to create a watertight layer.
As soon as possible after grading, the banks and surrounding areas should be raked clean, sown to a quality pasture seed mix, then rolled. From this point of view, farm pond design and construction is best done in early fall to give time for seeding to take hold. Shrubs or willows can be planted around the edge, not too close to the water, to avoid overhanging branches or exposed roots.
Renovating an Old Farm Pond Design
If you have recently bought an old farm, it may contain the remnants of a farm pond design. Renovation involves the same principles discussed above. Possibly only a good cleaning, scything and seeding is necessary. But if the banks are in bad shape and water loss is serious, it pays to hire the services of a skilled excavator, who will bulldoze away the errors of man and nature and get you off to a proper start. There is no need to be afraid of a little mud. As the sod grows thick and the water ripples brightly, the sloppy mess created by grading will be recalled only in photographs.
The average farm pond owner receives a lot of varied advice about fish stocking, fertilizing, weed and algae control. Like so many things in this world, moderation is the answer.
Farm pond fertilizing is a major consideration, because you want to provide enough nutrients for development of the tiny single-celled algae that are the basis for plankton. The indirect approach is best; where the acreage of the watershed above the farm pond is under your control, it can be correctly limed, fertilized and cover-cropped to prosper and help your farm pond prosper. A few ppm (parts per million) of nutrients, dissolved in water, go a long way toward plankton growth. Runoff water from fertile land can supply the need.
In fertilizing a watershed, a heavy spreading of compost should be avoided. Especially near the pond itself. Such spreading can be done just ahead of disking and replanting, so that the compost is incorporated with the soil and undue amounts are not washed downhill. Composting is best done in winter and early spring months so that contamination or serious fouling of the water is ended in time for summer swimming.
Under condition of poor watershed fertility, where surrounding land is not under your ownership or control, or in rocky and sandy localities, direct treatment of the pond must be undertaken.
Compost may be applied directly to the water with certain precautions. The material should be partially decayed, taken from a heap that has been standing for some time; it should be low in carbon content; spreading should not be done on the shorelines; and the application should be done in cool weather.
In this way, most of the solids will settle to the deeper bottom gradually releasing their value, fish and humans will not be greatly offended, and the floating debris will be carried downstream harmlessly. Organic matter around the edges of a pond bottom, in relatively shallow water, is not wanted. It encourages the growth of sessile algae and grasses, can be stirred up to roil the water and may create an oxygen shortage that will destroy young fish and tadpoles.
A moderate application of phosphate rock and green sand can be made in early spring, scattered uniformly from a boat or the shore. The average amount would be 250 to 350 pounds of each per surface acre (43,560 square feet), applied every other year.
Directly liming your farm pond design is seldom a worthwhile limestone use. Ground limestone is slowly soluble, due to reaction with natural carbon dioxide in the water and unless judiciously applied is likely to increase the pH of the water to an unwanted alkaline level, discouraging the growth of desirable algae and killing some fish. A spreading of crushed oyster shells can be made, avoiding shallow areas and swimming beaches, to provide a mild alkalizing effect. Surface waters and spring waters of farm and hardwood land tends to be alkaline, while those of mountainous or pineland areas are usually acid.
The most controversial phase of farm pond design and maintenance is weed control. It is unwise to neglect a farm pond until algae, milfoil, pondweed, duckweed, grasses or cattails take over, and then search for some magic treatment. There are situations where the use of copper sulfate may be justified, but reasonable care will solve most of your weed problems. This should include fairly steep banks plus a constant water level, adequate inflow and outflow to avoid stagnation, well-sodded and mowed banks, no stands of rushes or aquatic growth, stocking the right fish and fishing them hard, maintenance of fertile soil and cover crops on the watershed, and finally, sufficient fertilizing in the farm pond itself.
When all of these things are done, the water should have a slightly cloudy appearance, caused by the growth of desirable single-celled algae, upon which insects and small water creatures feed, the plankton complex, which in turn provides food for fish. Hence, unwanted growth should have a rough time getting started. The combination of plankton and an absence of warm shallow water spots discourage the development of the large, slimy strands and masses so often seen in a neglected or poorly built farm pond.
When such algae get started, developing from spores brought in by a water source or by winds, they should be raked or pulled out promptly. Under no conditions should arsenical or chlorinated hydrocarbon compounds be considered for eco-farm pond treatment. They are dangerous to all vegetation, aquatic life, land animals and humans.
Whenever unwanted vegetation is destroyed by any means, it should be removed from the water as soon as possible and carried away from the watershed. Otherwise, spores and seeds may re-infest the pond, and decaying material in the water take up valuable oxygen and cause suffocation of fish.
One of nature’s most efficient pond weed controllers is the ordinary duck. Domesticated mallard ducks do the best job, nibbling at weeds and grasses with little damage to bank structure. Pekin ducks do a good job, too, but spend more time at the shoreline, pulling out bits of mud and sod. A dozen ducks should be the limit, with the population held to a number that will do their work without becoming destructive. Geese will serve, but they need to be fenced in fairly close to the farm pond, since they spend less time in the water and can be very inhospitable to swimmers or fishermen. A simple fowl shelter should be placed near the shore, or on an island (especially if there are dogs or foxes roaming the area). A daily corn feeding should supplement their foraging.
Ninety-nine swimmers out of a hundred will jump into any water without checking bacteriological conditions. It is a proper precaution, however. Many of our streams, rivers and lakes are dangerously contaminated by intestinal wastes. Nature has the ability to destroy these organisms gradually, as well as many industrial by-products. But when the load is heavy, oxygen becomes depleted, biological activity is curtained, and pollution can remain for long distances.
If your watercourse is questionable, flowing through civilized areas, it is advisable to call upon a commercial laboratory to make biological analysis and advise on safety for swimming; a factor that may govern your decision whether to go in for farm pond building.
Where upstream stretches are generally rural or wooded, there is little danger of serious contamination, unless gross amounts of barnyard wastes reach the flow. Normal runoff from farm lots carries some manure, but natural balance usually exists, so that bacteriological counts stay within reasonable levels. It is wise, however, to fence off the watershed above stream and farm pond at least several hundred feet to keep grazing animals moderately distant. The droppings from a few ducks will not seriously contaminate the water, unless stagnant conditions exist.
If the water source has satisfactory bacteriological qualities, and no pollution occurs in the farm pond itself, there will not be any buildup locally. On the contrary, adequate inflow and outflow, proper plankton/insect/fish balance, and freedom from weeds all assure bacteriological control. And the plankton — is quite harmless to swimmers.
What about fish? You must decide on the kind of fish that are desirable and suited to your farm pond design. When and where to obtain them, and whether there is a competitive situation existing in the farm pond already. Old farm ponds may have a conglomeration of stunted, useless fish, multiplying rapidly but never growing to a decent size. These should be eliminated.
The best plan for de-stocking is to drain the pond and leave the fish high and dry to suffocate painlessly. Their remains make good organic fertilizer. If there is any likelihood of causing havoc downstream by allowing mongrel fish to be flushed out in draining, suitable screens should be placed to hold them back, just as there would be a screen at the inflow point to keep out uninvited species.
One of the most popular fish combinations is bass and bluegills, in a ratio of one to ten. Both are good eating and tolerant of differing water qualities. The bass develop mainly by devouring young bluegills, which in turn live on plankton, a complex mixture of small plant, water animal and insect life. The right time to stock is in early summer, late enough to be past the main breeding season for bluegills, but allowing a few months for the new fish to become acclimatized fingerlings one to three inches long, not grown fish.
There are alternative types of stocking. A farm pond with a fairly generous flow of water, well aerated, as from a hillside or mountain stream, can support a population of trout. Rainbows are best for western areas, brook trout for the northeast. But trout may not be stocked with other species. If you are inclined, the farm pond can be stocked with catfish. Again, it is useless to try to mix them with other fish.
Most states supply fish from hatcheries, at a nominal cost. Details can be obtained from your extension agent. There are many commercial hatcheries selling fingerlings in season at moderate cost. If you have doubts as to the best kind of fish to stock, whether water temperature and chemical conditions are suitable, and, how many fish to obtain, be sure to contact your local commercial laboratory consultant or fish hatchery representative. Many factors which are known to these experts govern the carrying capacity of your farm pond.
Having stocked the farm pond, there is one requirement: Fish! Fish should be pulled out and eaten. More farm ponds are underfished than overfished. Population crowding results, with many small fish, unfit for use, causing an even greater overpopulation. You can help nature keep a balance, first by stocking properly, then by maintaining and fertilizing the farm pond correctly and finally taking that bamboo pole down from the wall and using it.
Herons and kingfishers may take a fancy to your farm pond. Do not take alarm. At first, it may seem that they are robbing you of good fish. Actually, they concentrate on the runts and are more likely aiding you against overcrowding. Anyway, no one has ever found a humane method for chasing them away.
With common sense, you can be proud of your farm pond design and even the worm on your hook will appreciate being dropped into nice, clean water.
Originally published in 2009 and regularly vetted for accuracy.