Destroyed Ukrainian dam unleashes floodwaters, putting thousands at risk: Here’s what we know so far

A strategically important dam in Russian-occupied southern Ukraine was blown up on Tuesday, raising fears about safety, water supply, and Europe’s largest nuclear power plant, which receives cooling water from the reservoir upstream.

Russian and Ukraine both accused each other’s forces of an intentional attack on the Nova Kakhova dam. CNBC has not been able to independently verify the claims.

Footage verified by NBC News showed water cascading over the damaged dam, with evacuation efforts underway to protect thousands of people living in low-lying areas downstream.

The dam is situated on the Dnieper River and holds back an enormous body of water. It was built in 1956 as part of the Kakhovka hydroelectric power plant.

The Kakhovka Reservoir supplies water to the Crimean Peninsula, which was annexed by Russia in 2014, and provides cooling water to the Zaporizhzhia nuclear power plant, which is also under Russian control.

In addition, its water is used to supply hydroelectric stations, irrigation systems, and freshwater fish farms.

The U.N.’s nuclear watchdog said Tuesday it was closely monitoring the situation at Zaporizhzhia nuclear power plant. The International Atomic Energy Agency said via Twitter that it is aware of the reported damage at the dam, but there was no “immediate safety risk” at the plant.

Ukraine’s nuclear operator Energoatom said via Telegram that “the water level in the Kakhov reservoir is rapidly decreasing, which is an additional threat” to the nuclear power plant, according to a translation.

“Water from the Kakhovka Reservoir is necessary for the station to receive power for turbine capacitors and safety systems of the ZNPP. The station’s cooling pond is now full: as of 8:00 a.m., the water level is 16.6 meters, which is sufficient for the station’s needs,” the agency said.

The Conflict and Environment Observatory, a non-profit based in the U.K., said the Kakhovka Reservoir is known to be the “ultimate heat sink” for the Zaporizhzhia nuclear power plant, noting that it can remove heat from shutdown reactors and spent fuel pools. It warned the breach of the dam posed a “serious threat” to the plant.

Half the span of the Nova Kakhovka dam appears to have been destroyed and Russia’s TASS news agency reported that the structure is continuing to collapse, citing emergency services.

Meanwhile, a Russian-installed official in the Ukrainian town of Nova Kakhovka reportedly said in comments to state television that the dam would be impossible to repair.