Officials in the southern Ukrainian city of Kryvyi Rih say 112 houses have been flooded after Russian missiles hit a major reservoir dam nearby.
Residents of as many as 22 streets in two districts were urged to evacuate, city head Oleksandr Vilkul said.
He said that overnight two blasts were carried out to increase the water flow from the dam to the Inhulets river, and the situation was now "under control".
Ukraine said the strike was revenge by Russia for its recent counter-attack.
President Volodymyr Zelensky described Russia as a "terrorist state" after Wednesday's strike on the Karachunivske reservoir.
"You are weaklings who fight civilians," Mr Zelensky, who was born in Kryvyi Rih, said in his late night address on Wednesday. "Scoundrels who, having escaped from the battlefield, are trying to do harm from somewhere far away," he added.
This was an apparent reference to Ukraine's recent military successes in a swift counter-offensive in the country's north-eastern Kharkiv region. It has seen Ukraine's army reclaim swathes of occupied territory, forcing Russian troops to retreat.
The precise scale of Ukraine's gains has not been verified by the BBC.
In his speech, Mr Zelensky said the reservoir had "no military value at all".
Water supplies were affected by the attack in the city where more than 600,000 people lived before Russia's full-scale invasion of Ukraine on 24 February. Water broke through the dam and overflowed the banks of the river, officials said.
But speaking on Thursday morning, Mr Vilkul said water levels in the Inhulets river had now "dropped considerably". He said there were no casualties.
Moscow has not publicly commented on the reported missile strikes.
Russia's military had earlier admitted hitting energy-generating targets that caused widespread blackouts affecting millions of people in eastern Ukraine last weekend.