What are the two negative impacts of a hydro power plant on the ecosystem?

The negative impacts of hydro power plant on ecosystem are as follows:

1. Since dams always have a reservoir where the abundant quantity of water is stored, the blocking of flowing water causes harm to aquatic animals and their migration.

2. Dams also causes submerging of the nearby lands and all the natural areas, agricultural lands and hence requires relocating of the people who lived previously near the dam area.

3. Water from the reservoirs of the dams is lost due to evaporation at a faster rate as compared to flowing water.

4. Normally reservoir water has a lesser amount of dissolved oxygen and is cooler as compared to normal water. So when such water is released, it causes negative impacts on the organisms and plants downstream.