How does hydroelectric power cause pollution?

The major pollutant generated by hydroelectric power plant is methane, that has a warming impact much higher than that of CO2. This methane is generated in the reservoir that is created by building a dam across a flowing water body i.e. river. read more

Most hydroelectric power plants have a dam and a reservoir. These structures may obstruct fish migration and affect their populations. Operating a hydroelectric power plant may also change the water temperature and the river's flow. These changes may harm native plants and animals in the river and on land. read more

Hydropower is nonpolluting, but does have environmental impacts. Hydropower does not pollute the water or the air. However, hydropower facilities can have large environmental impacts by changing the environment and affecting land use, homes, and natural habitats in the dam area. Most hydroelectric power plants have a dam and a reservoir. read more

A hydropower plan will not necessarilly create pollution after it is built. It largely depends how it is designed, the topology of the terrain and the materials used to create it. If a dam is built, what Rachit Kansal said is likely to happen. read more