Hydroelectric power still requires the building of dams, turbines and piping, the production of which all produce pollution. Again I agree that it is much small

Hydroelectric power still requires the building of dams, turbines and piping, the production of which all produce pollution. Again I agree that it is much smaller than that produced during the lifecycle of a coal plant, but building something like the hoover dam is not pollution free. Additional use of resources due to inefficiencies is always going to result in more pollution unless we can eliminate pollution from many industrial processes.