The Kakhovka hydroelectric dam in southern Ukraine was captured in the beginning of the invasion because of its strategic importance: it supplies the Moscow-annexed Crimean peninsula with water.
The Russian-occupied dam is a particular focus now after Ukrainian President Volodymyr Zelensky accused Russian troops of planning to blow it up to trigger a devastating flood.
Located on the Dnieper River, the dam is one of the biggest facilities of its kind in Ukraine.
According to the website of its Ukrainian operator, Ukrgydroenergo, the capacity of the hydropower plant is 334.8 megawatts.
Built in Soviet times in the 1950s, the Kakhovka dam pumps water into the North Crimean canal, which starts in southern Ukraine and crosses the entire Crimean peninsula.
Upstream from the dam is the Kakhovka reservoir on the Dnieper.
The reservoir can hold 18km3 of water.
The dam and the hydroelectric power station were captured by Russian troops at the very start of the invasion on February 24.
Kakhovka is about 60 kilometres to the east of the city of Kherson, which fell into Russian hands a few days later in March.
The frontline is currently about 40 kilometres to the north of the dam.
If it were to burst, it would cause a “catastrophe on a grand scale”, Zelensky told the European Council on Thursday.
Hundreds of thousands of people around the lower Dnieper would be in danger of flooding, including the city of Kherson itself.
“This could destroy the supply of water to a large part of southern Ukraine,” as well as affect the cooling system for the Zaporizhzhia nuclear power station which relies on the Kakhovka reservoir.
Kremlin proxies in the Kherson region have denied any plans to blow up the dam, calling Zelensky’s assertions “lies”.
Any problem with the dam would cause water supply problems for Crimea, which has been under Russian control since 2014 and which Ukraine hopes to recapture one day.