Keep in mind
The North Crimean Canal is what has provided fresh water to the Crimean peninsula since the 50's. Its source is the Kakhovka Reservoir fed by the Dnieper river. When the Ruskies annexed Crimea in 2014 the Ukes cut off the fresh water supply from there. Blowing up the Dam will mean no fresh water for Crimea from that source for quite some time. I guess they figure the Ukes will cut it off anyway once they recapture Kherson Oblast.