The General law County owned parkway tree per 1968 Encroachment Ordinance has lifted and cracked public residential sidewalks in an unincorporated arra.
SHC, Section 22060. The board may remove any tree or any part thereof which appears to be dead, is liable to fall, is dangerous or is an obstruction to public travel, whether or not the tree is on any private property and overhangs or projects into any street or is in any street, park, parkway or other public grounds of the city. Since the County owns the tree, owns the tree roots, owns the parkway and the sidewalks that are raised and cracked, obstructing public travel, who is responsible to remove the tree(s)? They gain taxes for this removal, are required to maintain the public right of way based on SHC 941A and 1806, dedications
You can ask the city to remove the tree. If it is a danger, they may do it, or they could possibly ask you to remove it, and then if you don't, do it themselves and charge you.
Sometimes there is a practical solution: If there are a lot of citizen complaints (even from the same person), the County will address the problem. Sometimes they have simple algorithms, so to speak, that trigger action after a certain number of complaints are received. Often, even if the government owns the tree, owns the right of way, etc. etc., they have discretion to act, and not a mandatory duty. But it is unclear from your facts. If there are a lot of complaints, it supports removal, and supports any discretion they have to remove it. If there are a lot of complaints, and the tree ends up contributing to some danger the County would arguably have more legal exposure-- so it is in their interest to address the problem from some practical standpoints--- rather than by legal force. A citizen can only force the government to act in situations where there is no discretion (generally speaking). Codes that use words like "may" often are interpreted to give discretion (but not always). CAVEAT: I do not practice law in California.
Believe it or not but tree law can be quite complicated. There are many variables. I know two attorneys who are quite familiar with this area of law and perhaps could be the foremost authorities on the subject, at least as far as I know. You should reach out to them and see what can be done here.
All my comments here are intended for general legal purposes. None of my comments here establish an attorney-client relationship with anyone. None of my comments should be relied on in taking legal action without first consulting an attorney.
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