The Nova Kakhovka dam, a decades-old, Soviet-era hydroelectric facility spanning the mighty Dnieper River in southern Ukraine, was breached sometime overnight on June 6. The breach sent torrents of water cascading downstream, inundating villages and towns, prompting evacuations of thousands, drowning fields, and swamping farmlands and marshlands.
Ukraine immediately lay the blame on Russia, which has controlled the facility since just after the February 2022 invasion. For their part, Russian officials in occupied territories on the Dnieper's east bank accused Ukraine of destroying the dam to cover up for what they called a lack of battlefield successes. Neither side provided evidence.
The incident comes about six months after Ukraine seized back parts of the Kherson region on the west bank of the Dnieper River, including the city of Kherson. And it comes as Ukraine gears up for what is expected to be a major new counteroffensive against Russian forces, one that could change the course of the war.
One thing is certain: the flood is likely to end up being the worst environmental disaster since Russia launched its large-scale invasion nearly 16 months ago.
What Happened To The Dam?
It's not clear exactly.
Built in 1954 to provide electricity to southern Ukraine, the 3-kilometer-long Nova Khakovka facility, also known simply as Kakhovka, is one of six hydropower stations along the entire Dnieper, which stretches 980 kilometers -- from Belarus in the north to the Dniprovska Gulf and the Black Sea in the south.
The facility has been under the control of Russian forces since a few weeks after the February 24, 2022, invasion. It had been damaged previously; once in late October or early November. And sometime around November 11, an explosion likely caused by retreating Russian troops blew up part of the roadway over the structure.
That’s led some outside observers to warn of the possibility that the dam may have collapsed on its own – out of neglect, deliberate or not -- particularly given how swollen the upriver reservoir was, from spring melt of winter snows and runoff.
Since retreating from the western bank, Russian forces have dug in on the opposite bank, building fortifications and trenches and laying mine fields to deter any potential Ukrainian river crossing. They have also used the eastern bank to hammer Kherson city and surrounding districts, terrorizing the area and providing a sobering counterpoint to the elation that followed Kherson’s liberation by Ukrainian forces in November.
Sometime around 3 a.m. on June 6, Ukrainian officials said, part of the dam gave way, and in the following hours, the upstream water pushed through until the breach widened.
The national hydroelectric power company said the breach was caused by an explosion inside the engine room.
“The station cannot be restored,” it said.
Ukrainian officials blamed Russia.
“Russian terrorists,” President Volodymyr Zelenskiy said in a post to social media. “The destruction of the Kakhovka Hydroelectric Power Plant dam only confirms for the whole world that they must be expelled from every corner of Ukrainian land.”
WATCH: Boat after boat of exhausted and stressed civilians arrived in the flooded streets of Kherson on June 7. Some of the people had made it here from Russian-occupied areas on the east bank of the Dnieper River.
Ukraine’s military intelligence agency, meanwhile, warned last October that Russian forces had mined parts of the facility, including the locks and the buttresses.
Moscow-installed officials in the part of Kherson region still occupied by Russian forces accused Kyiv of striking the dam with missiles. Other Russian officials in the region, however, suggested the dam had burst on its own due to earlier damage.
Kremlin spokesman Dmitry Peskov accused Ukraine of “sabotage” and warned of “very severe consequences” for residents. He also insinuated that Ukraine breached the dam in order to cover a lack of battlefield progress: “it’s withering away.”
How Bad Is The Flooding?
Ukrainian emergency officials were evacuating thousands of people from districts on the river's west bank, where the river waters rose throughout the day. Video shot by RFE/RL’s Ukrainian Service and other footage circulating on Telegram and social media showed entire villages inundated.
The city of Nova Kakhokva, which had a preinvasion population of 70,000, was partly underwater particularly in neighborhoods closest to the river.
City officials said animals at the city zoo were likely all dead.
About 70 kilometers downriver is Kherson city, the administrative center of the region, and by the afternoon of June 6, nearly 12 hours after the dam was reportedly breached, waters were already flowing into some low-lying districts, particularly those in the marshy delta further down river.
Flood waters were seen rushing over the debris and wrecked pylons of the Antonivskiy Bridge, a major river crossing that had been rendered all but impassable due to repeated shelling by Ukrainian and Russian forces.
"Evacuation has started. I ask you to do everything you can to save your life. Leave the dangerous areas immediately,” Oleksandr Prokudin, the head of the Kherson regional military administration, said in a video.
Last October, the Swedish hydrological engineering company Damningsverket was commissioned to come up with a theoretical model based on what might happen if the Kakhovka dam was breached. It found that the swollen waters would reach not only the river mouth, but also push water up the Pivdenniy Buh River, to Mykolayiv, an important Ukrainian river port.
“Worst-case modeling,” the prediction read, found that “a 4-to-5-meter wave would hit the Antonivskiy Bridge east of Kherson city about 19 hours later, there would be a back swell flooding up the Inhulets River, and after four or five days there would be some flooding up the [Pivdenniy Buh] River to Mykolayiv.”
In Mykolayiv, an emergency train was dispatched midday on June 6 to the southeast to help evacuate people fleeing the rising waters in Kherson. The city’s mayor, Oleksandr Syenkevych, said there was no flooding as of midafternoon.
After the reports of the dam breach, Damningsverket CEO Henrik Oelander-Hjalmarsson said that water levels in the reservoir above the dam were at a 30-year high, most likely because the flood gates had not been left open during the conflict and during this spring’s melt.
“It’s a massive disaster and I’m deeply saddened the Russians have done this,” he told NBC News.
It Gets Worse
The reservoir formed by the dam stretches upriver, about 100 kilometers to the north, before widening into the Kakhovka Reservoir.
The reservoir is the main source of coolant for Europe’s largest nuclear power facility, the six-reactor Zaporizhzhya nuclear power plant, in the city of Enerhodar. The facility has been under Russian control since March 2022. Ukrainian engineers and operators have been working under Russian oversight since then.
The reactors have been shut down, not generating electricity, since September, after months of increasing alarm that fighting between Ukrainian and Russian forces could lead to a catastrophic meltdown.
Still, the dam breach endangers the plant because of dropping reservoir levels, which would harm the pools that cool radioactive fuel cores. The waters can be circulated, re-used, but if levels drop too much, the pools’ water temperature could climb. If they were to boil, or evaporate, the fuel cores would melt or explode.
By early afternoon on June 6, officials in the city of Nikopol, which is located to the north of the power plant, across the reservoir, said water levels had already dropped by 1.5 meters.
Enerhoatom, the Ukrainian state company that oversees the Zaporizhzhya plant, said as of mid-afternoon June 6 that the dropping water levels were so far not affecting the cooling pools.
"And even if there is no water in the Kakhovka Reservoir at all, the [facility] has measures to replenish, one of which is the use of underground well water" on the site, CEO Petro Kotin said.
The International Atomic Energy Agency said that it was monitoring the situation at the plant closely. There was “no immediate nuclear safety risk at plant,” the agency said in a post to Twitter.
The bigger question will come into the later summer and fall, when overall river levels will naturally drop, and Ukrainian officials will have to compensate in part with releases of more water further upriver.
What About Crimea?
Dropping water levels upriver from the Kakhovka dam also endanger something else: Crimea.
The Black Sea peninsula, which has been under Russian control since March 2014, is hot and arid, and its indigenous water supplies are limited to ground water from rains. For that reason, Soviet authorities built the 402-kilometer canal in the early 1960s, beginning at the city of Tavriisk, along with branches into mainland agricultural area.
With changing climate making Crimea’s weather hotter, and rains more sporadic, the North Crimea Canal took on outsized importance.
After Russia’s annexation of the peninsula, Ukrainian officials dammed the canal, drastically throttling back supplies, leading to shortages in the region. Invading Russian troops then took control of the canal and restarted water flows.
In a statement on Telegram in the morning of June 6, Crimea’s Russian-appointed governor, Sergei Aksyonov, said that the region had adequate reserves in its reservoirs – about 80 percent, he said -- but cautioned that water levels could drop, particularly as the region enters the hot summer season.
For agricultural regions under Russian control -- parts of the Zaporizhzhya and Kherson regions -- a lack of irrigation from a depleted Dnieper could also be disastrous.
Cui Bono: Who Benefits?
The destruction already under way downriver from the dam appears to be mainly hitting Ukrainian controlled districts, on the Dnieper’s west bank, though some settlements on the east bank, including the city of Nova Kakhovka are also affected.
That, plus the fact that the facility has been under Russian control for more than a year, has led many observers to lay the blame squarely on Russian authorities.
Add to that the looming Ukrainian counteroffensive, which is expected to occur in several locations along the nearly 1,000-kilometer front line that stretches roughly from the mouth of the Dnieper to the Russian border, northeast of the city of Kharkiv.
In recent months, Ukrainian commandos and sabotage units have been reported in a handful of locations and islands on the Russian-held east bank of the Dnieper. A flooded coastline would make the already difficult crossing even more problematic and provide Russian forces with yet another layer of defense.
The flooding and evacuations will also divert attention and resources from Ukrainian authorities who would otherwise be supporting the counteroffensive.
“They decided that now, in this way, they will be able to stop the counteroffensive of Ukrainian forces,” Natalya Humenyuk, a spokeswoman for Ukraine’s southern military command, told RFE/RL’s Ukrainian Service.
Also, there’s precedent.
In 1941, with Nazi German troops pushing hard through Soviet-era Ukraine, Josef Stalin ordered the destruction of a dam in the city of Zaporizhzhya, about a two-hour drive northeast of Enerhodar, to slow the Nazi advance. The breach swamped villages along Dnieper banks, killing thousands of civilians.
Overall, however, the destruction of the dam will have long-term ripple effects in how Ukraine stores and distributes water, not only for electricity generation but also agriculture, said Mykhaylo Yatsyuk, the director of the Institute of Water Problems and Reclamation of the National Academy of Agrarian Sciences.
"It’s necessary to understand that two-thirds of Ukraine's economy is tied to the cascades of the Dnieper reservoirs,” he told RFE/RL’s Ukrainian Service.