Supermassive concrete installations designed to resist ground and back pressure have abnormal reduction in applied pressure for extended periods.

WCPGW? I expected a little more on this. I know that in-ground pools "pop" when their load is removed, but thats a smaller scale effect. Removing the back pressure on a static dam wall cannot be without consequence. I'm expecting that the least outcome is an increase in cracking due to flex, but an opportunistic chance to both measure/assess and remediate issues "inside" the dam wall side.