The Fatnicko Polje - Bileca accumulation tunnel represents an integral part of the 'The Upper Horizons' system, a key part of the 'Trebisnjica' hydro-electric power system (HES). The basic concept of this system is the collection of accumulated waters of eastern Herzegovina into a single accumulation, so as to maximize effects of its numerous uses.

The 'Trebisnjica' HES currently consists of four hydro-electric power-plants (Trebinje I, Trebinje II, Dubrovnik, Capljina), while the completion of the system envisages building of three more hydro-electric power-plants (Dabar, Nevesinje, Bileca) and two more accumulation tunnels (Dabar-Nevesinje) and (Nevesinje-Rilje). These three hydro-electric plants will secure additional annual production of 300 MWh of power.