PLEASE HURRY 20 POINTS!! What is a possible disadvantage of using a hydroelectric dam as a source of energy?

A Hydroelectric dams can harm the aquatic ecosystems both above and below the dam.

B Hydroelectric dams can harm the atmosphere by producing toxic gas.

C Hydroelectric dams do not produce carbon dioxide emissions.

D Hydroelectric dams do not produce radioactive waste.

Hydroelectric power is also a renewable resource; however, Hydroelectric power can have negative effects on the environment. The natural habitat of many organisms is changed by the building of a dam or power plant. Salmon are harmed more than other organisms because they swim upstream to reproduce and the dams block their route. If they are unable to reach their spawning ground upstream, the salmon simply do not reproduce.

fe 55.85 g/mol and h2o 18.02 g/mol.