Rogun, set to be the world's tallest dam, passes 190 m of 335 m

What happened

Webuild, which is building the main part of the project, announced the milestone from Milan on 25 August 2026. The top of the dam's structure is now 1,155 metres above sea level. This allows the water in the reservoir to be raised by another 40 metres, to 1,140 metres above sea level. Ground Engineering, a British trade magazine, reported the news on 2 September.

The extra water matters because Rogun is producing electricity while it is still being built. Two of its turbines are already running. Webuild says that with a higher reservoir, the turbines have more head, the height difference that drives the water, so they can produce more power. When complete, the plant will have six turbines of 600 megawatts each, a total of 3,600 megawatts, which Webuild says will double Tajikistan's electricity production capacity. Webuild compares this capacity to the output of about three nuclear power plants.

Webuild says that about 49 million cubic metres of material have been placed so far, more than half of the total. More than 500,000 metres of drilling have been completed to strengthen the rock under the dam and to build the grout curtain. Webuild's part of the work, called Lot 2, is worth about 2.3 billion US dollars. The project is financed by the World Bank, Italy's Cassa Depositi e Prestiti and other international lenders.

Rogun has a long history. Ground Engineering reports that construction first began in 1976, in the Soviet period, and was restarted by the Tajik government in 2016. Early estimates aimed to finish by 2028, but an analysis by S&P suggests the work may extend toward 2035. Webuild says its own part of the work is on schedule.

The engineering behind it

Webuild describes Rogun as a rockfill dam with a clay core. In general, this kind of dam is a huge pile of compacted rock and gravel, with a central wall of clay that stops water passing through. The rock gives weight and stability. The clay core, which has very low permeability, makes the dam watertight. Each layer must be spread and compacted to a tight specification, because poor compaction can lead to settlement or leakage.

The ground under a dam matters as much as the dam itself. Water can find paths through cracks in the rock below and around the structure. A grout curtain is a common solution. Engineers drill a line of deep holes into the foundation rock and pump in cement grout under pressure, filling the cracks and forming an underground barrier. Rogun's 500,000 metres of drilling show how large that task is at this scale. Webuild's list of work also includes grouting galleries, which are tunnels inside and below a dam from which this drilling and grouting can be done.

Before any of this could start, the river had to be moved. Webuild explains that the Vakhsh River was diverted into two underground tunnels to keep the dam foundations dry. Because the river is so strong, that work could only be done in winter, when the mountains were frozen and the water level was low.

Building in stages is the most unusual part of Rogun. The dam rises, the reservoir rises behind it, and each increase in water level gives the turbines more head and more stored water. This brings income from electricity years before the project is complete. It also means engineers must design every stage to be safe on its own, with the dam holding a partly filled reservoir while construction continues on top.

What it means in Nepal

Nepal is preparing its own large storage project. Spotlight Nepal reported in March 2026 that the investment plan for the 1,200 megawatt Budhigandaki reservoir project, on the border of Gorkha and Dhading districts, had been formally approved. The base cost is estimated at 374 billion rupees, with a target of eight years to build. Major construction is planned to begin in Poush 2084, and most of the land has already been acquired. The plan is to fund it with 30 percent equity and 70 percent loans, including government loans at 1 percent interest and green bonds worth 30 billion rupees.

The questions Rogun is answering will matter for any project of this kind. Engineers must decide how to build a dam in stages, and whether it can generate power before it is finished. They must place and check huge volumes of fill, seal the foundation rock, and plan the finance and schedule over many years. Each of these tasks needs civil engineers who understand soil, rock, water and construction management.

The Rogun timeline is also a lesson in itself. A project that started in 1976, stopped and restarted, and may now take until 2035 shows that dam engineering is not only about design. It also depends on finance, politics, agreements with neighbouring countries and careful planning across decades. Webuild says Rogun will supply power for around 10 million people and allow electricity exports to Kyrgyzstan, Afghanistan and Pakistan. Those plans depend on transmission lines and trade agreements as much as on the dam.