Upper Horizons hydropower scheme, Bosnia and Herzegovina

Bosnia and Herzegovina is home to the largest undiscovered karst rivers, caves, and springs in Europe.

These hidden ecosystems are seriously threatened by the Upper Horizons hydropower project.

Consisting of a series of dams, diversion tunnels, hydropower plants and channels, the project will completely change the natural hydrography of eastern Herzegovina and will have unforeseeable impacts on wetlands, rivers and underground karst.

Due to the complexity of the project, its limited assessment, and the hidden nature of the karst fields and rivers, few people outside the affected areas know about the problems.

Species that are found only in the karst fields and nowhere else are likely to be driven to extinction.

If the Upper Horizons scheme is built, karst rivers, caves, and springs will be left with almost no water even before their biodiversity has been properly studied.

The olm, a unique blind cave salamander, is one of the species most vulnerable to these changes. It can live more than 100 years in a single cave and depends on the spring floods to feed on the nutrients they bring. Many of its populations are already impacted by existing hydropower plants and water pollution, and it has nowhere else to go.

Three different endemic fish species called ‘gaovica’ by the local people (Telestes dabar, Telestes metohiensis, Delminichthys ghetaldii) would probably be driven to extinction by changes in the rivers caused by the channels and tunnels of Upper Horizons.

In some of the caves impacted by the Upper Horizons, there are unique species of invertebrates that have not yet been researched.

Species that are found only in the karst fields and nowhere else are likely to be driven to extinction.

If the Upper Horizons scheme is built, karst rivers, caves, and springs will be left with almost no water even before their biodiversity has been properly studied.

Upper Horizons will affect villages in Republika Srpska, the Federation of Bosnia and Herzegovina (BiH) and even Croatia. In Republika Srpska, four unique karst fields (the Gatačko, Nevesinjsko, Dabarsko and Fatničko polje) will be completely destroyed along with the loss of traditional livelihoods. In Nevesinjsko polje, several villages will be flooded and many more will lose their agricultural land. In the Federation of BiH, several sinkholes will close or dry out, reducing the flow of water to the iconic Buna, Bunica and Bregava rivers, which are vital to towns like Blagaj and Stolac. The Neretva delta, an important agricultural area, is already suffering from salination. But with even less fresh water, the process could irreversibly damage the local economy.

The Upper Horizons project would divert 85% of the water flowing from the Buna, Bunica and Bregava rivers into the Bileca reservoir. The Upper Horizons project would involve closing or drying of several sinkholes. This would endanger the water flow to the iconic Buna, Bunica and Bregava rivers that are of crucial importance to towns and villages in the Federation of BIH, like Blagaj, Hodbina and Stolac.

It would also result in several sinkholes closing or drying up, heavily curtailing the water supplied to the iconic Buna, Bunica and Bregava rivers, which are of crucial importance to towns and villages in the Federation of Bosnia and Herzegovina (BiH) such as Blagaj, Hodbina and Stolac. An environmental impact assessment (EIA) of Dabar hydropower plant – the largest in the Upper Horizons scheme – found that more than 85% of the water from the Biograd sinkhole would be diverted towards the Bileća artificial reservoir. The Ponikva sinkhole and others that feed Buna and Bregava would also be left with almost no water after the building of two new reservoirs and channelling of the Dabarsko and Fatničko polje.

The water currently flowing into the Buna, Bunica and Bregava would be diverted to the existing Lower Horizons hydropower plants, never to return to the Neretva basin. As observed with the Lower Horizons scheme, not even the minimum volume of water intended to be left in some of the rivers would be monitored or enforced, the EIA concludes.

Upper Horizons will destroy two wetlands of international importance: Hutovo Blato and the Neretva Delta.

Hutovo Blato in the Federation of Bosnia and Herzegovina and the Neretva Delta in Croatia are two unique wetlands on the Adriatic bird migration flyway. They are protected under the Convention on Wetlands as wetlands of international importance.

If Upper Horizons is built, they will disappear, affecting birds, fish, amphibians and plants.

The water that feeds Hutovo Blato will be diverted towards the Dubrovnik hydropower plant.

Dabar hydropower plant and Upper Horizons will leave even less water in the Neretva Delta and will make it saline. The Neretva Delta is a very important area for agricultural  production and is already suffering from salinization of the soil. 

If built, Upper Horizons would destroy four sites of European importance: the Gatacko, Nevesinjsko, Dabarsko and Fatnicko karst fields. 

These karst fields (polja) are unique flat plains surrounded by limestone mountains. Their complex hydrogeological features include spring caves, estavelles, sinkholes, and disappearing rivers.  

Protected as Emerald sites, all four karst fields are designated Key Biodiversity Areas (KBAs) under the Bern Convention and Important Bird and Biodiversity Areas (IBAs) by BirdLife International. 

If Upper Horizons goes ahead, this unique landscape will be destroyed and converted to dams, reservoirs, channels and tunnels. 

Built in the second half of the 20th century, the Lower Horizons project has already had a devastating impact on biodiversity and livelihoods in East Herzegovina. The Trebišnjica River in the Popovo karst field has been completely transformed. While one section of the river has been diverted through a tunnel to Dubrovnik hydropower plant, the rest now flows into a channel serving Čapljina hydropower plant. As a result, the longest sinking river in Europe is no more.  

Due to changes in the Popovo polje caused by the Lower Horizons project, corn can no longer be grown. This has led to the closure of all the mills near the river’s sinkholes. These businesses used to employ natural and ecologically friendly methods of making flour. 

But it’s not only people that have been affected. Critically endangered underground fauna are on the brink. For instance, populations of the olm, or Proteus anguinus, have almost vanished due to construction of the Lower Horizons project. If built, Upper Horizons will only add to the suffering. 

Given the documented impacts of the Lower Horizons project on the regional hydrography in East Herzegovina, as we have seen in Popovo polje, there is absolutely no way that Upper Horizons should proceed.  

The entire Neretva river basin is under threat from dozens of hydropower projects slated for Ulog, Upper Neretva, Upper Horizons, Glavatičevo, and Ljuta.  

On 11 November 2023, people from all over the country protested in Konjic against the destruction of the Neretva and its tributaries.  

Stopping Upper Horizons is a crucial step in the fight for Neretva!  

We’re calling on the governments of Bosnia and Herzegovina to revoke these destructive plans and to provide legal protection for the last remaining natural river stretches in line with the recommendations of the Bern Convention on the Conservation of European Wildlife and Natural Habitats.