The water in the reservoir of the Nova Kakhovka dam is dropping following the dam's collapse last week, albeit slower than authorities initially feared, the CEO of Ukrainian hydroelectric company Ukrhydroenergo told CNN on Monday. 

"The reservoir has decreased by 50%. As for the volume, we estimate that there is 60% to 70% less water in the Kakhovka reservoir than there was before the blow-up," Ukrhydroenergo CEO Ihor Syrota told CNN. 

Syrota warned of "severe environmental consequences" if the water falls below critical levels — around 3 meters.  

"We hope that the lower hydraulic structure remained intact. If so, the level of the Kakhovka reservoir may remain within 6 to 7 meters. If it is damaged, it falls into the critical zone," Syrota said. 

Syrota added that the water supply to the Crimean peninsula may be restored by "summer of next year."  

"It is clear that the Crimean Canal will be drained, there can be no water there," Syrota said. "When Crimea is de-occupied, we will address the issue comprehensively — water supply for our four regions and Crimea. I think it will be no earlier than next year, after the floods."

"If for some reason this (de-occupation) does not happen, it will just be a blocked channel, because we will primarily supply Kherson, Dnipropetrovsk, Zaporizhzhia and Mykolaiv regions," he added. "These are the regions that will now suffer from a shortage of water, both drinking and industrial."