Egypt and Ethiopia have waged a diplomatic war of words over Ethiopia’s massive new dam – the Grand Ethiopian Renaissance Dam – on the Blue Nile, which started filling up in July 2020. The political row has threatened to get out of hand on occasion but now the two countries have finally agreed to conclude “a mutually acceptable agreement” within four months. We asked John Mukum Mbaku, the author of a recent article on the Ethiopian dam and a co-author of a book on the Nile River’s changing legal regime, to answer four key questions.