[Robert DeLong]

A letter they got in early May told them their backyard is 21-feet over the property line and that they need to remove their fence, shed, and other items that are over the line by July 31.

So, if like other cities and states, if a homeowner has maintained a public or private owned property for so many years, they can rightly claim that property as theirs, otherwise, the city is right in saying that they have exceeded their rightful property boundary.

This is Sacramento, so I don't know what their rules are with regards to this situation.

[DuncanWaring]

“Adverse Possession”

https://www.justia.com/real-estate/docs/adverse-possession/

[Sacajaweau]

No adverse possession against a municipality.