How smart was it to make a man-made lake on top of a limestone bed? And even if they fix it, won't this just happen again?
Depends on how stable it is. Limestone seems to have a wide variance of consistency, at least around here.
Yep. They might dump enough bentonite in it to plug it up, but the water will find it's way back out again. It's just a question of how long.
There's not much choice, as most of Missouri is a limestone bed. There are over 5000 known caves in the state, and everybody lives near at least a few. In many areas in Missouri, it takes a pretty careful site survey to make sure a house can be built safely, not to mention an artificial lake.