2)A huge amount of dangerous pollutants such as pesticides, ammonium and nitrate nitrogen, phosphorus, potassium and others are washed away from agricultural areas, including areas occupied by livestock complexes. For the most part, they enter the river without any treatment, and therefore have a high concentration of organic matter, biogenic elements and other pollutants.
3) The Ishim reservoir is mainly fed by the waters of the Ishim river, as a result of which there is a difference in mineralization by season. According to hydrochemical analysis of samples from the lower reaches of the Ishim reservoir, the mineralization increases to 0.5-0.8 g / dm3. The water in the reservoir has a pronounced calcium character.
4) Waste water from rural localities containing organic suspensions or dissolved organic matter adversely affects the condition of the studied reservoirs. Being deposited, suspensions fill the bottom and delay the development or completely stop the vital activity of microorganisms involved in the process of water self-purification.
