The work deals with controversies surrounding North American hydroelectric mega-projects, including some basic information and statistics of the dams and hydropower in the US and Canada. To allow deeper analysis, among hundreds of hydroelectric projects in North America, the text focuses on two specific developments only, namely Tennessee Valley Authority (TVA) in the US and James Bay Project in Canada. Brief history of both projects is provided preparing grounds for further discourse of the controversial issues. The paper introduces problems concerning large hydropower developments such as the need of governmental assistance, clashes between federal and state or provincial governments, questionable economic feasibility, conflicting objectives, adverse effects on the environment, inevitable displacement of people in the inundated areas and dealing with Native Americans in this respect. TVA and James Bay Project share plenty of features, however, each of them constitutes distinct realms. In addition to the North American hydroelectric developments, the work comprises imbedded data on similar structures elsewhere in the world for better context.