Only 1/3rd of the world’s great rivers remain free flowing. The rest are dammed.
Hydro power involves damming mighty rivers so that their majestic flows turn turbines to transform rotary motion into electricity. Every dam is an ecological disaster that destroys the ecosystem where it is located. The larger the dam, the greater the damage. The horrendous Hoover Dam, near Boulder, Colorado, has caused earthquakes.
The damn cost of dam construction and maintenance makes hydro power uneconomic on top of being environmentally outrageous. There were 3,185 hydroelectric dams in the world as of 2016, built at a total cost of ~$2.4 trillion.
The ecological impoverishment of rivers is particularly dramatic when a series of dams prevents interlinking different habitat types. ~ German biologist Juergen Geist