Hydropower dams are among the most complicated renewable power projects in the world, especially when the rivers they are built upon cross national borders. JP Casey looks at recent controversies in the hydropower sector to see what lessons can be learned ahead of future developments.

Hydropower dams are, in some ways, an elegant solution to the world’s increasing desire for reliable, renewable power, taking advantage, as they do, of geographic features already in place around the world, and providing a more local source of power than distant offshore wind farms or solar panels built in deserts. 

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These advantages have seen hydropower become a critical component of the world’s energy mix. A report from Vaclav Smil and the BP Statistical Review of World Energy found that hydropower made the biggest contribution to the world’s energy mix of any renewable source in 2019, with 10,455TWh, behind only coal, oil, natural gas, and biomass.

Yet these dams bring with them their own challenges, ranging from prohibitively high start-up costs to the considerable environmental damage that can come from interfering with a river’s natural course. Unique to hydropower dams, however, is a challenge of geopolitics: the flow of rivers across and beyond national borders means that the decision to build a dam is often not merely a local one influenced by energy policy, but an international one, directed by national interest and political will.

The history of hydropower is filled with examples of dams whose influence spans national boundaries, and whose consequences extend beyond a single country. From the discourse surrounding downstream impacts in north-east Africa to the rush for cheap power in Europe that has threatened local wildlife, the world’s hydropower dams exist at a unique intersection of political policy and environmental idealism. Tackling this range of challenges and obstacles can require similarly complex solutions.

North-east Africa

The most recent example of cross-border tension is in north-east Africa, where Ethiopia and Sudan have been at odds over the former’s construction of the Grand Ethiopian Renaissance Dam (GERD) on the southern channels of the Nile. The dam promises to be a massive construction, a $4.7bn project that could generate 6,000MW of power for Ethiopia and give the country an element of control over its own water reserves.

Sudan, however, has consistently objected to the project, saying that it will bear the brunt of the dam’s downstream damage, and recent objections are built on a tradition of disagreement. Following 10 years of negotiations, several countries, including Ethiopia, signed the Entebbe Agreement in 2010, which set limits on the share of the Nile that countries around the river can claim for their own. 

This agreement has since not been recognised by either Sudan or Egypt, driving a wedge between the two and Ethiopia.

Ethiopia, for its part, has pressed on with its construction, filling the dam with 13 billion cubic metres of water in July, ahead of what it hopes to be the start of production in 2022. Moves such as these have angered its neighbours, with Egypt objecting to the move entirely, and Sudan even calling into question the volume of water set aside by the Ethiopian authorities.

This conflict has spilled out into broader African geopolitics, with efforts from the Democratic Republic of the Congo, the current chair of the African Union, to bring the countries back to the negotiating table going nowhere. Rather than negotiating with their neighbours, Egypt has resorted to threats of military action if Ethiopia continues with the GERD development, perhaps emboldened by recent US support for Egyptian water security at a summit held between the two countries in early November. 

The conflict is a messy one and with looming threats of military action and US involvement in the background, the controversy remains a clear example of the challenges associated with cross-border river developments.

The Indian Subcontinent

In the Indian Subcontinent, the challenges of dam construction are not tied to a particular project, but to India’s interest in hydropower more broadly. In 2019, the government granted renewable energy status to hydropower projects, granting the same legal protections to hydropower projects of all sizes, and encouraging further construction of dams as India looks to meet its massive energy need; since 1990, its total electricity consumption has risen by a vast 459%.

The plan appears to be to encourage hydropower development to make up for the lost production from India’s vast coal facilities, which it agreed to “phase down”, to considerable objections, at the COP26 summit. This is a sensible decision, considering the growth that Indian hydropower has already enjoyed; between 2008 and 2018, the total energy produced by hydropower in the country increased by over 2,000 kilotons of oil equivalent.

Tungabhadra Dam in India
The Tungabhadra Dam in India opened in 1953.

Yet this growth has concerned India’s neighbours, notably Pakistan. The $1.18bn Pakul Dul hydropower facility, which covers waterways that flow into Pakistan, is set to be completed in 2023 and India increased spending on the dam by 61.25% in February this year. 

The move has raised concerns that India is throwing its financial weight around to prevent Pakistan from building similar facilities as much to secure its energy future, and to demonstrate to Pakistan that it controls the rivers and waterways that flow between the countries. Economic power, and political will, it seems, still reign supreme when making decisions regarding the future of these international projects.

South-east Asia

The Don Sahong dam, which was built by Laos and covers waters which flow into Cambodia, is an example of a dam with a relatively amicable political past, but one that has still encountered its fair share of challenges. 

The dam, a relatively small project which was only built to produce 260MW of power, is expected to produce 195MW. All of this will be sold to Cambodia at a price of $7.295 per kilowatt for the next 30 years, a reasonable price and a long-term deal that demonstrates how compromise and co-operation are possible in the world of cross-border dams.

Yet the history of this, and indeed other, dams on the Mekong river demonstrates the limits of the international agreements put in place to manage the river’s resources. The Mekong River Commission (MRC) was set up in 1995 to oversee industrial projects on the river, and draws its members from Cambodia, Laos, Thailand, and Vietnam, with China occupying a role as a “dialogue partner”.

While the MRC has published a number of reports into the present and future of the river, including plans for both the next five years and next decade of development, its advisory process, known as Procedures for Notification, Prior Consultation and Agreement, has reportedly been ignored by Laos. 

The Sanakham dam near the Thai border, for instance, was rejected by the advisory process after it was found that its application was copied from that of a different dam, yet the MRC lacks the legal authority to prevent Laos from working on the dam regardless. The recent history of cross-border negotiations in the region has been warm, but episodes like this highlight the legal challenges associated with such projects.

South America

Built on the Paraná River between Brazil and Paraguay, the huge Itaipú Dam is one of the largest and most productive in the world. Since its construction in 1984, the dam has produced 2.6 billion MWh of electricity, and currently produces 90% of Paraguay’s electricity, alongside 16% of Brazil’s, and is estimated to have generated $45bn in net value over the last four decades.

The Itaipú dam spans the border between Paraguay and Brazil. Credit: Börkur Sigurbjörnsson under CC-BY-NC-ND-2.0 license.

Yet a project of this size has equally significant environmental consequences, and the dam’s operators have planted over 44 million trees to compensate for the deforestation caused in the dam’s initial construction. The construction itself is believed to have generated around 11 million tonnes of carbon dioxide equivalent, significantly damaging the dam’s overall environmental impact.

Beyond these challenges, there are further geopolitical controversies. For instance, Brazil and Argentina have been in talks to release water from the dam to top up the declining levels of the Paraná River, an option that has been exercised in the past and has been agreed upon by both countries, but one that conspicuously leaves Paraguay absent from negotiations. 

With the emptying of the dam’s reservoirs set to have negative impacts on the dam’s ability to produce electricity, Paraguay would stand to lose the most from such an arrangement, yet is absent from the negotiating table.


The tension between generating renewable power and minimising environmental damage is one that often blights hydropower facilities, and none more so than the Vogelgrün dam between the French towns of Vogelgrün and Strasbourg, close to the German border. First built in 1959, the dam boasted an electricity generation capacity of 140.4MW, but was torn down in recent years due to pressure from environmental activists, who argued that the dam was obstructing the migratory patterns of local salmon.

Data collected by the Salmon Comeback organisation supports this, reporting a decline in the number of salmon identified in the Rhine River from around 75 in 2000 to just over 20 in 2013. This decline was particularly sharp in waters around the Iffezheim dam, where the number of salmon fell from 75 to around two in this period, and highlights the significant disruption to salmon populations in the waterways around the French-German border.

The eventual deconstruction of the Vogelgrün dam demonstrates a prioritisation of the welfare of local wildlife over energy production in the short-term, but in the long-term, could set a precedent where a greater range of opinions and actors are considered ahead of the construction of similar projects in the future. 

Hydropower dams typically affect a greater range of people than other renewable power facilities, both in terms of people affected in different countries, and different types of groups affected altogether. Perhaps the rise and fall of the Vogelgrün project will show that such complex issues can be addressed in a similarly sophisticated manner.