Interesting. The easement he is claiming is known as Rights of Water - there are many different types as you probably know. I thought such a right applied to water extracted from a river flowing through one landowner's property which then flowed onto the next landowner. This isn't your situation - how can he claim the groundwater you extract would have otherwise 'popped up' in his spring anyway. Landowners don't own the rights to all the earth beneath their land (to the earth's core?!) - I know this because I have come across LR legal title to stone mines where the LR ownership on the surface is entirely different. From memory, the owner on the surface owned the first 12 feet down. Just a few random thoughts for others to shoot down.