It was already reported that Russians were controlling the water levels behind the dam, and after keeping it quite low for a while had built it back up to a very high level, to do the most damage. Comment #108 gives a very detailed explanation of how Russia’s explosion ran away from them and caused much more damage than expected. Especially to Russian fortifications and supplies east of Kherson.. In addition, lowering water levels in the upper river will be easier for Ukraine’s troops to cross now by special means.
Typical Russian military incompetence.
The former lakebed will be impassable for months to come. Decades of built up silt will be mud and tracked vehicles and even men on foot will find it impractical to traverse.