Gabčíkovo–Nagymaros Waterworks, Hydroelectric complex on the Danube River, Hungary and Slovakia

The Gabčíkovo–Nagymaros Waterworks is a barrage system on the Danube, built only in part: the Gabčíkovo Dam in Slovakia has a hydropower plant and two lock chambers on the left bank, where the water level differs by about 20 metres, and a 10 m wide road bridge crosses the complex. The Hrušov reservoir, 16 km long and 1 to 4 km wide, holds 196 million cubic metres behind a 10.5 km embankment.

The 1977 Budapest Treaty committed Czechoslovakia and Hungary to a joint barrage system. Hungary suspended work in 1989 after the Danube Circle movement and scientific warnings, then tried to terminate the treaty in 1992. Slovakia built Variant C alone, diverting the Danube at Čunovo; the Čunovo reservoir was filled in October 1992 and the Gabčíkovo plant became operational in 1996.

The project represents a shared approach to managing a major European river between two nations. It shapes how both countries think about using water resources and generating power today.

You can view the complex from both riverbanks with observation points and walking paths offering different perspectives. The area is best visited outside of flood season when water levels are more stable.

The International Court of Justice settled disputes between Hungary and Slovakia over this project. This made it a landmark case in how countries resolve water-sharing disagreements.