Which of these is a disadvantage of hydropower?

Fish populations can be impacted if fish cannot migrate upstream past impoundment  

dams to spawning grounds or if they cannot migrate downstream to the ocean. Upstream fish passage can be aided using fish ladders or elevators, or by trapping  

and hauling the fish upstream by truck. Downstream fish passage is aided by

diverting fish from turbine intakes using screens or racks or even underwater lights

and sounds, and by maintaining a minimum spill flow past the turbine.

Hydropower can impact water quality and flow. Hydropower plants can cause low  

dissolved oxygen levels in the water, a problem that is harmful to riparian

(riverbank) habitats and is addressed using various aeration techniques, which  

oxygenate the water. Maintaining minimum flows of water downstream of a  

hydropower installation is also critical for the survival of riparian habitats.

Hydropower plants can be impacted by drought. When water is not available, the  

hydropower plants can't produce electricity.

New hydropower facilities impact the local environment and may compete with other  

uses for the land. Those alternative uses may be more highly valued than electricity

generation. Humans, flora, and fauna may lose their natural habitat.

Hope This Helps!  Have A Nice Day!!

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).