Question

Why is hot water discharge into river considered as a pollutant?

Answer 1

common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. When water used as a coolant is returned to the natural environment at a higher temperature, the sudden change in temperature decreases oxygen supply and affects ecosystem composition.

Answer 2

One of the major causes of water pollution is the discharge of waste from industries. ... Often, hot or contaminated water is also released into the rivers from industries, which increases the overall temperature of the rivers, thus making them unfavorable for the aquatic flora and fauna to thrive

Hope it helps you my dear friend..