Large areas had been meliorated (in 70-ties in my country Poland) so the meadows are gone for good outside of some protected areas.

All these wild weeping willow which had been a signature of Masovian landscape and which I still remember from childhood visits to family farm died soon thereafter. So did the frogs. It is like coming to different country now.

Same in Lithuania. Although it's not as permanent as you might think. In 90s many state farms went under and huge portions of land was left to it's own devices. By 00s, many of them turned into grass with wild flowers, tiny trees, and everything Wherever melioration failed, it was slowly nearing meadow-like conditions. Now big portions of it are used again either for agriculture or housing...

> Perhaps this is a sign that the freshwater in the ground is going away.

Now look what Nestle/other food giants, but also slaughterhouses and animal farms, do: they use groundwater with private wells, and they extract more water than can be replenished... boom.

I wonder if sabotaging such private wells, by conrecte blocking parts of the aquifying layer would constitute as self-defense.

Most likely not, and you risk disruption of underground water flows by injecting huge amounts of concrete into the ground...