What are the rights when a mine appears in one's property where the water source exits the land?

Primary text

If a mine appears on one's property such that the water source exits the land, and another person excavates from outside the property, that external excavator is entitled only to take what exits beyond the property boundaries. Ownership is limited to the parts of the subsoil that constitute the property itself. No one has the right to take what is situated within the boundaries of another's land, whether internal parts or external surface parts.