Human activity can significantly increase the aging process of a pond or lake. Excess nutrients derive from point and non-point source pollution. Point source pollutants (though it may not be considered as a pollutant by some standards) are fertilizers added to the water to encourage weed growth, excess nutrients from fish food that speed up the metabolic process in fish causing them to produce more waste, and waste products that are directly deposited by other wildlife. Typically, these issues are easier to correct. In most cases, discontinuing the use of fertilizers and excessive feeding will fix the problem.
Non-point source pollution, however, is nutrients deposited to the water that come from other locations such as runoff from fertilized lawns, livestock pastures, septics and sewers, etc. Non-point source pollution usually is a bigger concern than point source and more complicated to remedy. The most effective way to correct non-point source pollution from runoff and other sources is to prevent the nutrients from entering the pond. You can accomplish this is to create a diversion by adding a buffer area that can utilize the nutrients before it the pond or eliminate the source entirely like discontinuing the use of fertilizer for the lawn.
Regardless of how your pond is accumulating excess nutrients, they will cause the aquatic plants to grow at a rapid pace. The added growth can become unsightly, particularly as the plants begin to die off, and speeds up the aging process of your pond. As the dead plants start decomposing, the organic matter and soil will begin to build up and fill the pond. All the added nutrients, weed growth, and sludge will quickly turn an oligotrophic pond to a eutrophic pond.
Treating the Symptoms
The overall aging process of a pond takes a long time, and there are steps you can implement to your regular pond maintenance to slow the process. As mentioned previously, most ponds with proper management can reverse the symptoms of poor water quality.
Aquatic plants, algae, and the gradual aging and filling of your pond or lake are all symptoms. There are several options for algae and aquatic plant control. However, just treating the symptoms repeatedly becomes costly and does nothing to solve the source of the problem.
An abundance of nutrients is the root of the problem with poor water quality and an aging pond. Although oligotrophic lakes and ponds are considered as young bodies of water, they can be hundreds of years old. Eutrophic lakes and ponds, though usually considered as old bodies of water, can be just a few years old. This is due to excess nutrients.