This is a tricky question with many considerations. It is important to recognize that most dams were not built primarily for hydropower purposes, and only 3% of the nation’s 80,000 dams currently generate electricity. If you were to get rid of hydropower, most dams would still be needed, as they play a critical role in public safety (flood protection), water supply (for homes and agriculture), recreation, and transportation (locks). In many instances, hydroelectric renewable power is simply an ancillary benefit.
Dams can and do impact the environment, sometimes changing natural flow patterns or interfering with fish and aquatic life. And not all dams are beneficial. Some dams, often built many years ago, are no longer needed or used as intended. In these situations, removing the dam may be the most prudent and responsible action.
Not all hydropower facilities even use dams. There are several ways to generate energy from hydropower:
Storage Dams: Moving water flows downward from an elevated reservoir to a lower reservoir or back into the natural river.
Run of River (ROR): Dependent on the natural flow of rivers, ROR hydropower diverts a portion of the river water to a turbine. Vulnerable to natural fluctuations in water level, there are more variables related to natural water cycles and their impact on water flow to generate electricity.
Pumped Storage: In some situations, the water can be pumped back uphill after it has gone through the turbine and used over and over to make electricity. Pumped storage hydro can even be designed as a “closed loop” system, where there is no connection to any river.