how to maintain deeded rights to water from a well on another property which has now been donated to the adjacent community forest

You will need a lawyer.  If it were any other kind of easement, I would tell you to tender the dispute to your title company. Unfortunately, the title insurance you got when you purchased the property 30 years ago, probably excludes water rights. You should still check your title policy, but I am not confident that it will cover this dispute. Next, a lawyer could send a couple of letters to the city attorney, detailing the evidence in support of your property's right to use the well. If that didn't work, then you would need to sue. That's one of the reasons to have a lawyer send the letter. It will demonstrate to the city that an attorney has looked at the matter, determined that you have a good case, and is ready to sue. This will be an expensive case to take to court. Probably $20,000.00 to get it to where the city might settle, and more than $50,000.00 if you actually have a trial. Do you really need the well?  Dana Sack