Eutrophication is the natural process whereby a confined water body (e.g. lake or dam) ages with time due to accumulation of silt or organic matter in the lake (Ademoroti, 1996).
A young lake is characterized by low nutrient level and consequently low plant productivity and at this stage is described as oligotrophic (few food) lake. The water body gradually acquires inorganic and organic nutrient from catchment areas and these promote aquatic growth and increased biological productivity causing the lake to become murky with decaying organic matter and phytoplankton. The water body is said to be eutrophic (well fed) and consequently, the decaying organic matter depletes its available oxygen. Increase in the accumulation of silt and organic matter, makes the water body shallower and sunlight penetrate slowly to the bottom, making the water warmer. Plants take roots along the shallow edges and the lake slowly transforms into a marsh or swamp which may eventually lead to dry land (Ademoroti, 1996).
Anthropogenic impact and seasonal climatic changes have aggravated eutrophication in water bodies worldwide. Advancement in science and technological innovation in agricultural practices has resulted in increased usage of natural and synthetic manures rich in phosphorus, potassium, and calcium in farming. These have accelerated the natural process of eutrophication worldwide. Nations of the world are conscious of the famous Malthusian economic theory and hence fight against this detrimental prediction by increasing food production through the construction of dams for irrigation and energy.