Many people don't know that the first test of the Endangered Species Act was used to try and stop a runaway federal agency called TVA. TVA wanted to build an extension of sorts Ft Loudon Lake called Tellico Lake and they connected via a canal. Tellico Dam does not generate power it has no generators. It simply increased the pool capacity of Ft Loundon Lake. TVA by it's own admission building Tellico Lake was a monetary and energy looser that would not pay for itself.
The opposition too the lake as such wasn't environmentalist but local land owners of prime farm land and sportsman. There was several dams upstream but the river was good Trout fishing water.
A biologist found what they thought at the time was a fish {Snail Darter} common only too that river and that was the how those opposed chose to try and bring an end too TVA's roughshod you'll do as we say or else tactics.
After several court battles the project finally died out so everyone thought. But Sen Howard Baker and Rep John Duncan Sr ran a midnight bill through to fund completion.
What was done after that should anger anyone who believes in property rights. Landowners who had even a small portion of their property touching the TVA high water boundary were forced to sell the entire parcel. Meaning if you had 500 acres and one tenth an acre was lake front TVA got the 500 as well. TVA then sold it to developers for a song. The original landowners had their land sold for many times over what TVA paid and what developers had paid TVA.
Hydro power still has lots of untapped potential. The dams along my river provide much better boating and fishing opportunities than the undammed areas. Run-of-the-river generation and small dams add smaller amounts of power than large dams, and create no blockages or other problems. The large dams you are talking about have been created by a large out-of-control bureaucracy. Despite them screwing over some landowners, the amount of new power and new recreation is very large despite losing the trout and other migrating fish. In any case trout can easily be farmed and replaced in any stretch of the river where they are desirable.