Eutrophication is derived from two Latin words meaning "good" and "food". For Fresh water, the term eutrophication refers to enrichment of lakes, ponds and stream with inorganic plant nutrition especially phosphorous and nitrogen.

Lakes receive inputs of nutrient and silt eroded and running off from the surrounding land basin.  Eutrophication is the name given to this natural nutrient enrichment of lakes. Over time, some lakes become more eutrophic, but other does not because of differences in surrounding basin (G.T Miller).

The process of eutrophication happens from both natural and cultural causes. In natural eutrophication, the organic material like leaves, plant residue etc. from the surrounding accumulate to the lake after washing from rain, river and stream, then decomposition of these matter occurs in the lake enriching the plant nutrient. Cultural eutrophication happens due to human activity. Agricultural field and animal farmland are highly fertilized area and when it rains, fertilizer from these land runoffs to the lake, causing nutrient enrichment in the lake. Also near urban area human activities can increase the nutrient in the lake resulting cultural eutrophication.

Phosphorous and Nitrogen are limiting nutrient in the lake. Their levels in the lake determine primary productivity. When these nutrient increase sharply then algal bloom results in the lake. Algal bloom is a sudden explosion of algae due to nutrient enrichment. With the increment of algal population, water become more increasingly turbid. This turbidity is due in part to the single-celled algal organisms present in the water and in part to dead and decaying organic material. The turbidity coupled with the appearance of algal mats, which can sometimes reach from shore to shore, render eutrophic bodies of water unappealing to swimmers and boaters.

During the past 40 years, eutrophication has become an increasing threat to the usability of South African freshwater resources. Ginkel (2011)