Check out the video of this 2 year old girl addressing a corporate committee with a coloring of a river she is trying to save, along with her parents of course.  It is a protest of a river run power project. 

Dams aren't needed, but I suspect it uses pipes top draw water upstream boost it's speed and energy with gravity, run a turbine, and exhaust the water downstream.  It can dry up part of the river at a crucial season, even though it isn't a dam type hydro project.

There are devices to harvest some of the power of moving water without interupting the flow or disurbing fish and wildlife, or wild rabble rousing kids frollicking in the river.  Old, young, and inbetween, all young at heart.

More on (hehey. I said more on) these river run and current generators coming.  Steady local green power for riverside homes and communities, happy wildlife!  It is posible without massive pipes and construction and destruction.