Thermal Pollution:

It is caused by addition of hot effluents and hot water bodies. Warm water contains less oxygen. So there is decrease in rate of decomposition of organic matter. Green algae are replaced by less desirable blue green algae. Many animals fail to multiply. Trout eggs fail to hatch while salmon does not spawm at higher temperature.

Agriculture sources.
Use of high yielding varieties of crops increased the demand for fertilizers are carried to ground water by leaching. They are also added through surface run off. Many pesticides are non-degradable. Huge amount of animal excreta-dung, piggeries are either discharged into grazing fields or dumped into pits.