2 disadvantages would be damage to Marine life and hydroelectric plants are very expensive.If they plant is not stable and breaks it can cause flash floods and property damage.2 advantages would be that they do not emit any carbon emmissions.Some cities cannot build hydroelectric power plants because the stream does not have that kind of pressure .so really it matters greatly on where the dam would be placed. but sunny places like arizonasolar plant would be great
I hope this help
