A hydroelectric dam produces renewable energy for the local area. Which best explains why more hydroelectric dams are not built?

The dam disrupts the river wildlife and ecosystem.

Explanation:

Though it is believed that using the dam as a power generation or hydroelectric power supply generates no greenhouse gases, it, however, has many disadvantages which make it deemed not suitable or sustainable for use in the contemporary time.

Majorly, the top reason why more hydroelectric dams are not built is that "the dam disrupts the river wildlife and ecosystem."

Also, it affects the water quality and other use of water for humans such as recreational use.

There is also a possible chance of dams producing methane; a greenhouse gas through the organic materials in the water that is rotting.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.