Gabčíkovo–Nagymaros Dams

The Gabčíkovo–Nagymaros Dams (more precisely Gabčíkovo–Nagymaros Waterworks, Hungarian: Bős–nagymarosi vízlépcső, Slovak: Sústava vodných diel Gabčíkovo – Nagymaros) is a large barrage project on the Danube.

The plan was to divert part of the river into an artificial canal at Dunakiliti (a village in Hungary) to the hydroelectric power plant near Gabčíkovo (eight turbines, 720 MW).

An important provision of the treaty was its Article 15.1, which stated: "the Contracting Parties shall ensure, by the means specified in the joint contractual plan, that the quality of the water in the Danube is not impaired as a result of the construction and operation of the System of Locks".

Biologists worried that the dams would damage both the treasured scenery of the Danube Bend and the underground water reserves on which more than a million Hungarians depend,[6] especially around Budapest.

In the end it was decided to switch to an alternative solution on a smaller scale, Proposal C. The artificial canal would start at Čunovo, part of the Slovak capital city Bratislava, and the Gabčíkovo power plant would operate in run-of-the-river mode with no water level fluctuation.

In October 1992 diversion of part of the water into the canal started and the Čunovo reservoir was filled; the secondary structures (such as the power-plant) were finished and made operational in 1996.

This level was to be located between the Hungarian towns of Visegrád and Nagymaros and its purpose was to use the gradient of the reservoir for production of electricity and also to allow ships to pass.

[citation needed] Non-existence of Nagymaros dam also causes main obstacle of inland navigation on the 2400 km Danube Pan-European corridor due to low levels of water.

Hungary requests Slovakia to manage regulation works on problematic stretch of Danube that were supposed to be solved by Nagymaros backwater.

Besides other issues, the Hungarian representatives wanted the court to decide whether or not Czechoslovakia was entitled to embark on Proposal C, and to rule that the 1977 treaty was not binding on Slovakia and Hungary.

In a letter dated 12 July 2017, the Agent of Hungary stated that his Government "did not oppose the discontinuance of the proceedings instituted by means of the Request of Slovakia of 3 September 1998 for an additional judgment".

Groundwater levels are dependent on big floods, like in 2002, which removed fine silt from river bottom and allowed increased filtration.