Lake Eutrophication

Eutrophication is one of the stages in the life cycle of a lake which happens over a period of years. Eutrophication is a natural process where the oxygen levels in the lake decreases as it ages and eventually just becomes a wetland.  

But due to pollution and industrialization, this process has fastened. Eutrophication is a state where the lake becomes toxic with high levels of nitrogen and phosphorus and they are heavily silted. Eutrophication may be defined as inorganic nutrient enrichment of waters, leading to the growth of algae. Many lakes are in this state, this happens due to human activities, extensive agricultural practices and major anthropogenic activities like global warming, deforestation and large scale environmental destruction that has led to harmful effects on the ecosystem. 

Image by: tnluser

Effects of Eutrophication: 

A lake when there is limited availability of Phosphorus and nitrogen then it is called “Oligotrophic”, when there is higher levels of these chemicals available then it is called “Eutrophic”. An intermediate state is called as “Mesotrophic state”. 

The productivity of the lakes are high in the Eutrophic state, this causes major changes in the waterbody. 

  • There is reduced visibility in the lake because of discolouration. The light penetration is very low because of the algae blooms. When there is no light penetration, photosynthesis no longer occurs. 
  • Oxygen levels in lakes differ and no longer can sustain ecosystems. 
  • Eutrophication causes dense algal blooms and injures the aquatic ecosystem by poisoning of the water, clogging of gills and high nutrients in the water. 
  • Abundance of organic substances give the water disagreeable odors or tastes. 
  • The lake is prohibited from any social activity.
  • Eutrophication damages the ecosystem by decreasing the biodiversity and by increasing the water toxicity.

Why do water bodies become so rich in nutrients?

Phosphorus and Nitrogen are the main limiting factor for the ecosystem in freshwater. Phosphates tend to stick to the soil and carry along with it. Hence, Soil erosion is one of the main contributors to Eutrophication. Other sources of phosphorus are:

  • Fertilizers
  • Detergents
  • Untreated Sewage
  • Industrial Discharge
Image by: tnluser

As years pass by the algae in the lake die and sink to the bottom of the lake and are broken down by bacteria in the process they consume oxygen.  This over consumption of oxygen, decreases the oxygen levels in the lake. This condition tends to suffocation and death of fishes and plants in the water. 


The process of Eutrophication can be controlled at the inlet channels of the lake by not allowing phosphorus rich substances. Avoiding the overuse of fertilizers and encouraging people to adopt organic farming methods.   Water must not be commercialized but rather considered as a heritage protected and saved. Despite many efforts taken to improve the water quality, it results in pollution, fires and algal blooms. The action to prevent and protect these water bodies must be adopted not only in scientific ways but by citizens and with support of likeminded organizations. 

2 thoughts on “Lake Eutrophication

  1. Oxygen levels are reducing along with lakes we need to increase the rate of trees minimal every street should have 10_15 trees , the government should make it mandatory that each house should grow a tree

    Liked by 1 person

    1. Yep you are right; instead of that government should grow trees themselves. Even our corporation made 5 places miyawaki forests. That should be increased. On the effects on lakes, their should be trees in the banks of it. More than NGOs and individuals if Government takes action on doing these things , it will be more effective.


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