What really happened to the Kakhovka dam? Nickolai Denisov, a researcher who’s studied the ecological consequences of the war in Ukraine since 2014, explains what may have caused the disaster — and what to expect next

On the morning of June 6, water began to flow uncontrollably down the Dnipro River after the Kakhovka dam in the Russian-occupied part of Ukraine’s Kherson region was destroyed. Kyiv says the Russian military blew up the dam. Moscow, on the other hand, blames “Ukrainian military groups.” Meanwhile, some open-source intelligence analysts suggest that the dam may have collapsed on its own due to “unprecedentedly high” levels of water in the reservoir. Nickolai Denisov, a geographer and one of the founders of the Swiss environmental non-profit organization Zoi Environment Network, has studied the ecological consequences of the war in the Donbas since 2014 and the destructive impacts of Russia’s full-scale invasion on Ukraine’s ecology. Meduza asked Denisov to help decipher the contradictory accounts of what happened to the dam and explain the subsequent flooding’s possible consequences.

What do we presently know about the destruction of the Kakhovka dam? Based on reports from the Ukrainian energy company Ukrhydroenergo, an explosion occurred in the engine room, effectively destroying the Kakhovka Hydroelectric Power Plant, says geographer Nickolai Denisov.

The water will only stop flowing from the reservoir when it reaches either the Dnipro river’s natural limits or the lowered level at which the dam might still operate, Denisov told Meduza, adding that it’s unlikely much water will be left over in the Kakhovka reservoir after the flooding is done.

According to Ukrhydroenergo, this could take anywhere from two to four days.

Ukrhydroenergo, the Ukrainian state-owned enterprise responsible for overseeing numerous power plants along the Dnipro and Dnister rivers, lost control over the Kakhovka plant months ago, making it unclear exactly how the facility was administered or under what conditions it was operating before Tuesday. “It’s hard to say who did what wrong where,” explains Denisov, but he supposes that the reservoir’s water level before Tuesday’s explosion was likely due more to natural conditions than mismanagement.

Asked if he thinks heightened water pressure combined with Russian occupation forces’ clumsy supervision might have been enough to break the dam, Denisov explained that his sources say these Soviet-era dams were usually built to withstand substantial force — even a direct missile strike, at least in theory. There’s no reason to distrust Ukrhydroenergo’s assessment that the cause was an explosion in the engine room, he told Meduza. “I’m not a military expert, but I do think this was [Russia’s] attempt to halt the advance [of Ukrainian troops],” he added.

It’s hard to say exactly how much the water levels will rise, but Denisov expects it to be at least several meters. (A single meter is more than three feet.) Water-level spikes will be lower further downstream, where the spill area is larger, but that nuance will be lost on the locals caught in floods, he says. Some preliminary calculations, however, anticipate even worse overflows.

How soon residents can return home safely depends on how quickly officials can restore critical infrastructure. Since the area is located close to the front lines, it’s hard to predict how combat operations could affect such restoration efforts. As for the organisms living in the reservoir, Denisov explains that they are adapted to the reservoir’s specific ecosystem, meaning that many won’t survive these floods. The dam’s destruction has also disrupted the local population’s water sources and irrigation systems. This will affect Crimea, since the Kakhovka reservoir supplies the North Crimean Canal, which provides water to the Crimean Peninsula.

The collapse of the dam has also sparked concerns about how water shortages will impact the Zaporizhzhia Nuclear Power Plant, which relies on water from the reservoir. Denisov says that water shortages resulting from the dam’s destruction could make it difficult for the station to cool the temperature of its reactor. Meanwhile, Ukraine’s state nuclear power company, Energoatom, reports that “everything is mostly under control,” and the plant has access to backup water supplies, for the time being.

Possible alternatives for supplying cooling water could involve either routing pipes and pumps to the river or “intensively exploiting groundwater,” though this is no easy feat in an area so close to the front lines, notes Denisov. 

In other environmental fallout, the flooding has reportedly caused 150 tons of engine oil to contaminate the Dnipro River, with another 300 tons still seeping in. Denisov estimates that this amount is roughly equal to four or five railway tanks. In terms of addressing the consequences of the ongoing flooding, he says it’s impossible to influence the speed of the water, since it’s “a natural process.” It is possible, however, to pump out some excess water if there’s proper access to the flooded areas, pumps, and electricity.

Overall, though, it looks like it’ll be a matter of waiting until the water levels subside.

As far as rebuilding the dam, Denisov cites estimates that it’ll take between one to one and a half years. “It’s a matter of strategic and political will — what the people and government there want [to see],” he told Meduza. “It’s definitely an ecological catastrophe,” he answered, when asked if the dam’s destruction constitutes Europe’s largest ecological catastrophe in decades. The Chernobyl disaster also looms large, of course.