Eutrophication of water bodies has been studied since 1970. It is an urgent water pollution issue that needs to be addressed. In the past, eutrophication often occurred in reservoirs, lakes, or watersheds where water bodies have a slow flowing speed. Eutrophication or hypertophication refers to the accumulation of nutrients due to the addition of external nutrients into the water system (lakes, reservoirs, and wetlands). Eutrophication, according to nutrient concentration, can be divided into four types: oligitrophic, mesotropic, eutrophic, and hypertrophic. Read more..