The Fatničko Polje–Bileća accumulation tunnel is an integral part of the “Upper Horizons” hydro-system in eastern Herzegovina. The concept behind the system is to accumulate waters in the fields of eastern Herzegovina during rainy periods and later move it through a system of tunnels, producing energy and creating valuable arable land.

The building of the “Upper Horizons” hydro-system began in 1969 but was not completed owing to building problems and later conflicts in the region. Among the unfinished parts of the system was the Fatničko Polje–Bileća accumulation tunnel.

In 2001 the authorities in Bosnia and Herzegovina called an international tender for the completion of the tunnel. EFT’s bid, in consortium with Bosnia’s Hidrogradnja, was by far the best. The company committed to invest EUR 26 million in further digging of the tunnel, completion of its concrete lining and the installation of control mechanisms and infrastructure.

In December 2006 the Fatničko Polje–Bileća accumulation tunnel was officially put into use, signaling the successful completion of the biggest civil engineering project in Herzegovina. The tunnel now produces some 150 GWh of energy per year by supplying additional flood waters to existing hydro-electric power plants in eastern Herzegovina.

The project directly employed some 400 people during construction, and several hundred more indirectly. It is environmentally sound and sustainable, and has no adverse effects on the surroundings. For more information regarding the environmental impact of this project please see (Analysis of the effects of water transfer through the tunnel Fatničko Polje - Bileća reservoir,
Part-01.pdf, Part-02.pdf, Part-03.pdf, Part-04.pdf).