Hydropower has important environmental benefits, but it can also have negative environmental affects as well.

Advantages of hydroelectric dams:

  • Hydropower is renewable.
  • Greenhouse gas emissions are very low under normal conditions, particularly in non-tropical regions of the world.


  • Dam reservoirs cause large loss of land.
  • There is significant damage to ecological systems, both upstream and downstream of the power plant.
  • In tropical regions, substantial amounts of methane, a powerful greenhouse gas, can be released, as submerged flora decay under anaerobic conditions.