Should big hydropower be counted as renewable energy towards meeting a Renewable Portfolio Standard for a state? It generally isn’t, but that could be changing as states scramble to meet their RPS goals.
Construction of big dams is indeed destructive to surrounding area. Really massive dams can heighten the risk of earthquakes. However, virtually all potential sites for big hydropower in the US are already being taken so few if any new ones will be built. Hydropower certainly is renewable, so why not count it as such?
One problem is that if big hydro is counted as renewable, then states will need far less new renewable energy to meet goals and thus less development of renewables within states. In New England, big hydropower is indeed available, but it comes from Canada. New transmission lines will need to be built. NIMBYs don’t like that.
The Connecticut Senate just passed a bill saying large hydro, including Canadian power, can be used to meet their RPS. The governor of New Hampshire strongly opposes it.
All across the U.S., state governments are wrestling with their renewable energy standards, weighing the costs associated with renewable energy economic development against the perceived added electricity costs to ratepayers.