And this can take decades, until swimming in the water doesn't impact health. Let alone the fact that the additional water to maintain the water level in an unnatural lake like that may be needed elsewhere. What many people forget is that during the excavation all kinds of metals and materials are uncovered leading to red water for the first couple of decades until everything is settled. I am from a german region (Lausitz) where all of that happened and believe me when I say that I'd rather have some out-of-the-job miners than big patches of land filled with lakes instead of "home towns".

It was the last old forest in Germany. Like, it was a forest for 12000y, basically since the last ice age. Individual trees are only a couple hundred years old, but the ecosystem you get from many generations of trees growing in a mostly unmanaged forest is rather unique and due to the time scales involved irreplaceable.

Forests take time to grow and mature. Animals that live in these forests often have nowhere to go when these are cut down. Especially smaller species may not have the ability to flee when the saws come. Also, forests in Germany often are reduced to unconnected patches separated by open fields. Large connected forests are rare.

Rehabilitation won't reverse the CO2 emissions. So yes, it's really so bad.