Book excerpt: The design of a hydroelectric plant, along with an installation of transformation of potential energy of water into electricity, is an activity that is not standardized. Each new project is an interesting engineering challenge, and teams need to work in different conditions of each site, integrated to design a functional, economical and environmentally sustainable project. The development of a project, here understood as the plant itself, the reservoir, the maneuver substation and the associated transmission line, is a multidisciplinary activity that encompasses areas of civil engineering, geology, mechanical and electrical engineering, environmental engineering, economic engineering, construction and assembly, and the engineering of operation and maintenance of civil works and electromechanical equipment. The book is organized to facilitate the performance of professional life of the new generations of engineers who will join the Electric Sector, or in other sectors that demand the knowledge regarding hydraulic structures. The book is a simple manual providing the practical step-by-step procedure for designing hydroelectric plants, including legislation, with a general view of the project.