Note: hydro sources, of which we have gigawatt potential here in Maine, are not counted as "green".
The next big environmental deal will be water conservation. The EPA will require all users, even in water abundant locales to use is as if they were in the Sahara Desert.
Its going to be a lot harder to generate power by using water. It sounds silly but you got to know the government will find a way to declare water pushing as turbine as wasteful.