Well, someone started raising the water level in the Kakhovka Reservoir running up to the bursting.
This is from an upcoming article:
Raising the water level
The first step in the Ukrainian plan was to boost the water level in the Kakhovka Reservoir.
Ukraine controls five of the six dams along the Dnipro River, which runs from its northern border with Belarus down to the Black Sea and is crucial for the entire country’s drinking water and power supply. Only the Kakhovka dam — the one farthest downstream in the Kherson region — is controlled by Russian forces.
In other words, all of the water in the Kakhovka Reservoir depends on the five Ukrainian-controlled dams upstream.
Theia-Land, a French organisation that monitors water levels worldwide, shows that the water level in the Kakhovka Reservoir was raised from 14 metres to 17.5 metres in the weeks leading up to the attack.
This was due to the Ukrainians opening up the floodgates on the next dam upstream from Kakhovka — the Dnipro Dam, which runs the Dnieper Hydroelectric Station, the largest hydroelectric power plant in Ukraine.
