The River San Francisco, very famous since the time of the discovery of Brazil, is in this article as general focus of analysis, being unfolded and contextualizado in the thematic one of its transposition. This article approaches a context controversial, a time that shows the ambient impacts that the River San Francisco supports front the action human beings whom they intend to modify its course, to change its volume of water, being alleged benefits of communities that are located in its course. Our intention in this article is to analyze the ambient River San Francisco and impacts that can elapse of the project of transposition of its waters, analyzing the advantages and cons of the action human being of intervention in a so old natural resources how much proper Brazil. The methodology adopted for the present research was fruit of the bibliographical research in books and articles on the subject, that had taken in them to conclude that many are the divergences in the context of the transposition of the River San Francisco. The care with the environment must be redoubled and the prevention of possible ambient impacts will be treated in our text, as form to prevent that measured remediadoras they are not infinite. Words key: Waters. Transposition. River San Francisco. Ambient impact.