In the state of California. We have 1 nieghbor where we live. We have 20 acers and they have 20 acers next to us. They don't have a water well. My husbands grandfather said they coulf use our well for a year while they dug 1 of their own. This was 7 years ago.
They have not even attempted to put their own well in.
And now theyhave moved and have left their livestock there. They leave their hoses turned on full blast and leave.
Because of this we got a 900.00 eletric bill because that kept the pump runnig around the clock. We were the ones that had to pay this, and he laughed about it thinking it was funny. So my husband shut the water off going to his property. Put a cap,chain and lock on it. The guy came onto our property in the middle of the night and cut the chain and turned the water back. And he again flooded his property at our expense. So my husband went out and cut a piece if the pipe out. He called the cops. Can they legally tell him to turn the water back on?
And what steps should I take to keep the water off.?

Do you have anything in writing that says they could use your well for only 1 year until they dig their own? The problem here is is the doctrine of adverse possession. You continued to let them use the water past the deadline. That might have granted them an easement. You should have shut off the water after the year was up.

Bottomline is you need an attorney to advise whether you have granted them an easement by your inaction. If you have, then you may have to deal with it by running an unpumped line to the property line and make them use their own pumps. However, if you haven't, then you can sue them for the additional cost after you shut off the water the first time.