Region-Wide Evacuations Underway After Attack on Ukraine's Nova Kakhovka Dam. Here’s What We Know So Far

A local resident makes her way through a flooded road after the walls of the Kakhovka dam collapsed overnight, in Kherson, Ukraine, on Jun 6. Credit - Evgeniy Maloletka—AP

The collapse of a huge dam in a Russian-occupied region of southern Ukraine has triggered flooding, with both Russia and Ukraine blaming each other for its strategic destruction.

The Nova Kakhovka dam, built in 1956 on the Dnieper River—30 km east of the city of Kherson—was breached as the result of an explosion Tuesday morning. Ukraine accuses Russian forces of blowing up the dam, which could also impact the nearby Zaporizhzhia nuclear power plant, while Russian officials say Ukrainian military strikes in the contested region caused the damage, according to the Associated Press.

The Russian-installed mayor of Kherson, Vladimir Leontyev, called the explosion a “terrorist act.” At present, it is unclear which nation is responsible or what either side would serve to gain from damaging the dam, which is said to have already been in a state of disrepair.

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Ukrainian President Volodymyr Zelensky has coordinated an urgent meeting of the National Security Council in response to Tuesday’s attack. In October, Zelensky urged Western allies to warn Russia not to attack the dam, noting that it would cause “a large-scale disaster.” At the time, the leader suspected Russian forces had planted explosives in the dam.

Below, what to know about the attack, and more.

Why is the Nova Kakhovka dam significant?

The dam is 30 meters (98 ft.) in height and 3.2km (2 mi.) in width, containing a reservoir of around 18 cubic kilometers (4.3 cubic mi.) of water, about the same as the Great Salt Lake in Utah. As such, there are growing concerns that the sheer volume of water will severely damage nearby homes and low lying areas.

Residents in 10 nearby villages and parts of Kherson have been advised by the Ukrainian Interior Ministry to gather essential items and evacuate the area. Polluted water supplies and wider environmental consequences are anticipated as a result of the incident. Water levels were expected to reach a critical level within 5 hours of the collapse.

But water from the dam’s reserve supplies the Crimean peninsula, which Russia illegally annexed in 2014, in addition to the Zaporizhzhia nuclear plant, Europe’s largest. The dam also helps power the local hydroelectric plant in Kakhovka.

‘No immediate’ risk to Zaporizhzhia nuclear plant

The Zaporizhzhia Nuclear Plant relies on water from the Dnieper River to cool its emergency diesel generators and reactors. Currently, the water reservoir is falling by two inches per hour, meaning that the supply of cooling water should last at least a few days. The U.N.’s International Atomic Energy Agency wrote in a statement that “there is no immediate risk to the safety of the plant.”

The IAEA’s director Rafael Mariano Grossi also said that there were additional water sources that officials could turn to, including a large cooling pond near the nuclear site that is above the height of the reservoir. The agency is hopeful that this pond may be able to cool reactors and diesel generators for several months, but this has not yet been confirmed.

Ukraine’s nuclear operator Energoatom said via Telegram echoed the IAEA’s assessment, saying that the dam attack “could have negative consequences” for Zaporizhzhia but that the situation is “controllable.”

This is not the first time that the Zaporizhzhia plant has become a focal point of the war. In March 2022, fighting caused a fire to break out at the facility that was extinguished just a few hours later when Russia officially captured the plant from Ukraine. The nuclear plant is capable of producing up to 6,000 megawatts of electricity, powering up to 4 million homes.

However, there is a chance that nuclear waste from the Chernopyl disaster could be disturbed by the flooding, according to Vlad Mykhnenko, professor at Oxford University who studies the urban development of post-Soviet countries.

“There is potential that those deep reservoirs in the Dnieper River have quite a bit of nuclear waste,” Mykhnenko told TIME. “All those deposits could be moved around through wind and dust.

What the attack means for Ukraine’s spring counteroffensive

The destruction of the dam has negative consequences for both Russia and Ukraine, with both countries racing to conduct evacuations of nearby residents. Mykhailo Podolyak, an advisor to Zelensky, has claimed that the destruction of the dam primarily benefits Russia, according to the Financial Times.

“The purpose is obvious: to create insurmountable obstacles in the way of the advancing Ukrainian armed forces,” said Podolyak.

David Helms, a retired American scientist who has been studying the dam since the war began, told the Associated Press that Russia has a history of attacking dams.

But the dam’s destruction also poses issues for Russia since the flooding will impact Russia’s defense forces in Kherson on the east of the Dnieper river.

Ukraine has long been expected by many experts to announce a counter offensive attack soon to try and break the land bridge connecting mainland Russia with other Russian captured territories like the Zaporizhzhia and Kherson provinces, though the military has not officially revealed any information about such a plan. Breaking this land bridge would make it much more difficult for Russia to provide supplies and coordinate plans with captured Ukrainian territories. The flooding in the region would make that plan much more difficult to execute.

“Basically, it denies any ability for us to cross the river and move equipment in that area. Essentially, that’s why most likely Russia did it, particularly now,” Andriy Zagorodnyuk, a former Ukrainian defense minister told the Financial Times.

However, some experts believe that the dam’s destruction won’t impact Ukraine’s plans significantly.

“There is not a lot of evidence that Ukraine was actually planning to cross the Dnieper because that would require a significant amount of ships and equipment,” Mykhnenko told TIME. “So I don’t think it will really significantly affect the Ukrainian offensive operations. “

Nevertheless, even if the dam’s destruction has little impact on Ukraine’s tactical plans, Mykhnenko expects the humanitarian impact to be severe.

“The river was providing drinking water to a lot of people… and that will obviously lead to drought and massive damage to farming in those areas, which are quite fertile for grain production,” Mykhnenko says. “I think we’ll probably have more damage than we expect from this disaster,”

This is a breaking news story. Check back for updates.