That is the question of the day, and one that concerns me when it comes to drilling a well to keep a pond topped off. The last thing I would want to do is dry up a neighbor's well in the sake of aesthetics or my recreation.
Now if I was using the pond for aquaculture and that was my living... growing and selling fish, that would be a different matter.
If you went before a judge with a socialist slant, they would side with the farmer since the irrigation can benefit many... and that is their livelihood. You should sacrifice for the greater good.
A conservative libertarian judge would simply say the laws are written that what you get is what you get out of your own mineral rights, other people need not concern you since that is the way the law is written. If you run out of water, dig a deeper well, or have it trucked in.
Another judge in the middle would have the farmer either supply your water, or assist in digging your well deeper.
Now all kidding aside... too many people dipping from the same resources has historically gotten humans into some pretty ugly spots. Just pray the past few dry years is simply part of longer-term natural weather cycles. Climate change is making them more extreme, but shouldn't effect duration.
