Gabčíkovo–Nagymaros Dams


The Gabčíkovo–Nagymaros Dams is a large barrage project on the Danube. It was initiated by the Budapest Treaty of 16 September 1977 between the Czechoslovak Socialist Republic and the People's Republic of Hungary. The project aimed at preventing catastrophic floods, improving river navigability and producing clean electricity.
Only a part of the project has been finished in Slovakia, under the name Gabčíkovo Dam, because Hungary first suspended, then tried to terminate, the project due to environmental and economic concerns. Slovakia proceeded with an alternative solution, called "Variant C", which involved diverting the Danube, the border river. These caused a still unresolved international dispute between Slovakia and Hungary. Both parties turned to the International Court of Justice for a ruling.

Budapest Treaty

The joint Hungarian–Czechoslovak project was agreed upon on 16 September 1977 in the "Budapest Treaty". The treaty envisioned a cross-border barrage system between the towns of Gabčíkovo, Czechoslovak Socialist Republic and Nagymaros, People's Republic of Hungary. The dams would eliminate regular flooding and provide a clean source of electric power. They would also allow year-long navigability of the river and serve as a part of the Rhine-Main-Danube Canal system of inland navigation.
The plan was to divert part of the river into an artificial canal at Dunakiliti to the hydroelectric power plant near Gabčíkovo. The canal would return the water into a deepened original riverbed and at Nagymaros a smaller dam and power-plant would be constructed. The plant in Gabčíkovo was to be a peak-power plant and the dam in Nagymaros, about 100 km downstream, was to limit fluctuations of the water level.
Because most of the construction was planned to occur in Slovak territory, the Hungarian government was obligated to participate in some construction in Slovakia, to ensure equal investment by both sides. Electricity produced was to be shared equally between the two countries.
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".

Limited project

In 1981 the two countries agreed to slow down the project because of their economic problems. In 1984 a movement protesting against the dam, the "Danube Circle", was founded in Hungary, which was later awarded the Right Livelihood Award and the Goldman Environmental Prize for protecting the Danube. The group objected to the withholding of information on the project from the public by the Communist government to avoid debate on its environmental impact. 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, especially around Budapest. After an intensive campaign the project became widely hated in Hungary as a symbol of the old regime. In Slovakia, construction continued and many people were involved in building the hydro-electric plant. The Hungarian government eventually decided to suspend work until the environmental effects of the project were fully assessed. Soon after, the Slovak authorities decided to unilaterally proceed with an alternative solution, called "Variant C". This effectively diverted the Danube into Slovak territory and kept the development entirely within its borders. This scheme dramatically reduced the amount of water flowing into Hungary and had a significant impact on that nation's water supply and environment. As a result, the Hungarian government attempted to terminate the 1977 Treaty.
The 7 proposals originally put forward by experts from Czechoslovakia in 1992 were as follows.

ProposalDescriptionComment
AComplete the original plans from 1977 together with Hungary.Slovak preference
BComplete only the Czechoslovak part of the waterworks.
CReduce the reservoir, build the waterworks only on the territory of the Slovak Republic and postpone construction at Nagymaros in Hungary. Split the shared reservoir into two with a dam and instead of the dam in Dunakiliti build a dam in Čunovo. This variant is called temporal, as it is technically possible to build the Dunakiliti dam and flood the Čunovo dam in order to finish the waterworks according to the 1977 treaty.winning project
DComplete only the upper part of the dam and finish the Dunakiliti dam.
EUse the waterworks only for flood prevention and ensure navigability.
FStop construction and retain the site in its current state.
GRemove all buildings and return the river to its original state.Hungarian preference


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. Construction started in November 1991. In October 1992 diversion of part of the water into the canal started and the Čunovo reservoir was filled; the secondary structures were finished and made operational in 1996.

Parts of the waterworks

Built parts

The waterworks on the Danube were designed to have an additional level at Nagymaros, consisting of a reservoir 95 km long and the Nagymaros power plant. 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. The Gabčíkovo works were designed for control and peak running of the power plant, and the Nagymaros works as an equalising power plant to provide better conditions for shipping and to regulate peak outflow from Gabčíkovo. Because the Nagymaros works were not built, the Gabčíkovo power plant cannot work at peak efficiency, which causes appreciable economic damage.
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 had to be solved by Nagymaros backwater. Transportation damages include also missing upgrade of river Váh waterway in Slovakia.

Lawsuit

After Czechoslovakia split up in 1993, the newly established Slovak Republic carried on with the project. In 1989 Hungary abandoned the site when scientists on both sides of the border expressed fears about the environmental consequences. After Hungary tried to terminate the 1977 treaty in May 1992 both
parties agreed to take their dispute to the International Court of Justice in The Hague.
In 1994, the Socialists came back into power in Hungary but could hardly back out of the court case, which was hailed as a landmark: for the first time, the court would rule over an environmental dispute. Hearings on the case were held between 3 March and 15 April 1997, and the Court paid a site visit. 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. The court handed down a decision in 1997:
Another four months of negotiations between Slovakia and Hungary led to a treaty between the two countries about the ICJ judgment. In March 1998 the government of Slovakia approved this treaty, but the government of Hungary, which was supposed to build Nagymaros or a Pilismarót waterworks, delayed approving the treaty and proclaimed a competition for the project. After elections in Hungary, the new government cancelled this competition. In 1998, after two appeals to Hungary, the Slovak government turned to the International Court, demanding the Nagymaros part be built.
The international dispute was not resolved for more than a decade. In June 2017, the Slovak Government requested that the International Court of Justice “place on record the discontinuance of the proceedings”. 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”.

Technical parameters

Regarding the environmental consequences of the dam, results of a 1996–2002 study by K. Holubová, Z. Capeková and J. Szolgay were:
Annual joint studies of the Slovak-Hungarian governments claim:
Differences between 2002 study and newer works may be attributed to size of studied area. As 1996–2002 study was done on area from Vienna to end of Slovak-Hungarian Danube. Government studies are targeting only Gabčíkovo waterworks and immediate area around it.
Groundwater levels are dependent on big floods, like in 2002, which removed fine silt from river bottom and allowed increased filtration. After that groundwater levels on many places reached pre-reservoir filling levels, on some places reached even higher.
Damming of the Danube improved ground water quality at Rusovce and Čuňovo water supply which are on right side of Danube. It was due changed infiltration conditions and changed groundwater flow direction from NW-SE to N-S. The ground water quality at water supplies situated on the left side of the Danube were not influenced to the same extent as on the right side.
One of the same problems identified is increased sedimentation upstream and riverbed erosion downstream from reservoir, which is a typical problem of water reservoirs.