Pollution of fresh waters — hit of various pollutants in waters of the rivers, lakes, underground waters. Occurs at direct or indirect hit of pollutants in water for lack of adequate measures for cleaning and removal of harmful substances.

In most cases pollution of fresh waters remains invisible as pollutants are dissolved in water. But there are also exceptions: foaming detergents, and also oil products floating on a surface and crude drains. There are some natural pollutants. The compounds which were in the earth of aluminum get to system of fresh reservoirs as a result of chemical reactions. High waters wash away from the soil of meadows of compound of magnesium which cause huge damage to fish stocks.