How to Maintain Farm Ponds? | Geography

The maintenance of farm ponds is generally done in respect of those points, which are counted for their protection. The maintenance is very essential, if their service is desirous to realize throughout their expected life. Severe damage of the dam and spillways is the result of lack of pond’s maintenance. In order to prolong the pond’s life and to have better service, it is very essential to maintain the pond very sincerely.

The maintenance of pond is done as under:

1. Vegetation:

The vegetations such as algae and aquatic plants are the integral part of pond’s ecosystem. These vegetations consume CO₂, oxygenate the pond water, provide food for small aquatic organisms and also create hiding place for fish. The aquatic organisms are also eaten by the large fishes, which provide food for waterfowl and other animals. Aquatic plants clean the pond water by consuming unwanted chemicals, cooling the water by creating shades and also provide shelter for breeding the fish and waterfowl.

Availability of these vegetations in pond water in suitable range is beneficial, but in excessive amounts they can cause nuisance in pond. At excessive quantity of vegetations there is possibility of interference in the use of pond, in addition to being detrimental to the eco-system.

The following are the categories of aquatic plants suitable for pond eco­system:

i. Phytoplankton:

These aquatic plants are commonly called algae. These are found in floating form in pond water. At lesser quantity these are not visible to eyes, but when they are in large quantity in pond, then the water appears as translucent green, brown or red, depending on their species.

ii. Submersed Plants:

These aquatic plants are grown in the sediments lying at the pond bottom. Leaves and stems of these plants are completely submerged in the water. These plants are normally found in floating form in pond water because of their thin and flexible stems. The most commonly found varieties are eelgrass, curly-leafed pondweed and Eurasian milfoil.

iii. Rooted Floating Leaf Plants:

Like submersed plants, these are also grown in the sediments lying over the pond bottom. They also have flexible stems but their leaves are large and flat, as result they float on the water surface. The water lilies are very common vegetations under this category.

iv. Emergent Plants:

These aquatic plants are grown in the sediment layer lying over the pond bottom. Leaves of these plants are very rigid, and projected above the water surface because of stem support. The cattail and bur-reed are very common species of this category of aquatic plants.

v. True Floating Plants:

These plants are floating on the water surface. These are also grown in the sedi­ment layer lying over the pond bottom. Their roots are in suspended form; and freely float in the pond water. The duckweed, water chestnut, planktonic and filamentous algae are the common species.

Aquatic Vegetation Control:

The control of aquatic vegetations from pond water can be performed by using following methods:

i. Physical Removal:

In this method, it is very important to identify the vegetation species to be removed from the pond water, first. After that they should be removed either by hand, rake or hoe. Care is always taken that their roots should not be left in the water; otherwise, they are likely to get develop again in the water.

Nowadays, machines have also been developed for this purpose, which are very convenient for larger beds of aquatic plants. However, the machines are very expensive; and their use results a large amount of weeds to disposed off; and also not remove the roots, completely.

ii. Nutrient Input Control:

This is also one of the very important control measures. In pond when sufficient nutrients are present then aquatic plants develop vigorously, as result the plant population becomes very large and their growth is to the extreme level. The sources of nutrients may be from the streams, surface water and ground water. In this condition such growth of aquatic plants needs to control, which can be suitably done by controlling the nutrients availability in pond water.

It can also be done by reducing the amount of fertilizer application in upstream area of pond. Also, the consi­deration must be given on agricultural land within contributing watershed, that it should be properly managed regarding fertilizer use, and use of erosion control practices. In addition, if pond is located in the wooded area, then surface runoff from these areas should be checked, because runoff water of these areas contains huge quantity of nutrients from the rotting leaf and other organic matters.

iii. Pond Lining:

The pond lining can also fulfill the task of vegetation control in pond water. The pond lining can be done by using plastic sheets of suitable thickness. This prevents the light to reach the soil, and inhibits the plant growth. Normally, for lining purposes 300-500 micron thickness polyethylene sheets are used. These sheets are very hard, as result the vegetations become unable to come out, above.

iv. Biological Control:

The Grass Carp can be an effective means of weed control in the pond. This species are sterile and non-predatory fish that eats exclusively aquatic vegetations. This species of fish should be stocked at the rate of 5 to 10 fish per acre; and they should be restocked at about every 5 years. Grass Carps are selective in their eating habits.

They prefer tender plants as compared to those with more rigid stems. They also convert plant materials to fish excrement. In other words, they make available large quantities of nutrients into the water. In addition, the insects can also be used as a means for control. The species such as Eurasian milfoil is one of the main.

v. Chemical Control:

The dyes such as Aqua shadow can be used to control the penetration of certain amount of light wavelengths preferred by the plants in the pond water. These dyes are generally inert, vegetative-based and are fairly inexpensive. However, for vegetative control the herbicides are commonly used.

Although, there are several types of commercial chemicals are available, but they are species specific which can be used for the specific vegetation species. The application of chemical for vegetation control in pond can cause decomposition of plant materials resulting into release of excess nutrients in the water, and reduction in oxygen level. These two effects may cause fish killing.

vi. Erosion Control:

The erosion control from exposed surfaces of pond such as dam, spillways and any other disturbed areas should be fully protected. It can be performed by planting a suitable vegetation to develop a good cover over exposed surfaces. If there is bank erosion due to wave action, then bank protection from wave action should also be carefully done. The bank erosion can be controlled by using a kind of wave barrier, which absorb the wave force, significantly.

Normally, for this purpose a single or double row floating logs are used. The bank erosion can also be controlled by riprap using boulders. The boulders should be of bigger size, so that due to wave action they could not get remove from the bank. For making the riprap more effective to check the erosion, the boulder packing should be done with little foundation for about 2 feet more in the pond’s lowest expected water level.

2. Inspection and Repairs:

Farm ponds should be inspected periodically, especially during heavy rains, so that the faults developed can be searched out and their proper repairs can also be done. Immediate action always eliminates the need of more costly repairs in later stages.

The rills formed at the sides of the dam and washes made around the spillway should be filled with suitable materials, and should also be thoroughly compacted. The development of rills on dam section and washes developed around the spillway are the result of soil erosion. This type of happening is the indication of either absence of vegetation or not application of protection measures on dam section.

The slope area of dam should be reseeded or re-sodded, and fertilizers should be applied, if required. If there is wash or slough in earth dam due to wave action towards upstream face, then they should be protected by installing the booms or ripraps. By the way, if there is seepage through or under the dam then an appropriate measure for that should also be followed.

The vegetative cover developed on the dam and around the spillway should be maintained by mowing and fertilizing, time to time, when needed. Proper mowing controls the formation of woody growth and also develops a uniform cover and root system, which provide sufficient resistance to the runoff.

Sometimes, burrowing animals also cause severe damage to the dam or spillway. If such damages remain unrepaired, then they can lead to failure the entire dam. The burrowing can be discouraged by providing a thick layer of sand or gravel fill around the dam or spillway.