Hydrelectric dams are less damaging to the environment but they still cause problems, mainly with fish populations and then there is the overall impact to the river by blocking the waterways they essentially flood the area upriver. Celilo falls was buried because of a dam which was a complete and total sham for the native american tribes that called Celilo their home and fishing grounds for centuries. Dams can control natural flooding but they also alter the land forever (until they are removed) I do not see The Dalles ever loosing their dam just to bring back Celilo Falls.
I am unsure of how wind farms impact the environment, I have heard stories of flocks of birds flying into the blades and getting killed but other then that I am unsure. They do take up a lot of space but there is still viable land underneath them. Many wind farms are incorporated in actual farms like wheat fields or corn fields.