What is eutrophication?

Natural eutrophication is the natural aging of a lake by biological enrichment of its water. Due to this, lakes gradually become more productive. It normally takes thousands of years for this to occur. However, when pollutants from man's activities like sewage, effluents from industries, agricultural wastes etc. are released into the lakes, the aging process of lakes is greatly accelerated. This is known as accelerated eutrophication. This phenomenon has been widely seen during the past century.