First, I have to make a disclaimer that the thought of digging through this in order for someone to use it regarding a neighbor makes me feel a little icky, but on the other hand, people who own houses here but don't live here aren't neighbors.
Anyway, someone at the Neighborhood Meeting brought up the topic of landlords who do not maintain their property, and I said that you could view the municipal code oneline. Here's the link:
This is the specific section having to deal with keeping grass less than 12" in height:
http://library4.municode.com:80/default-test/template.htm?view=browse&doc_action=setdoc&doc_keytype=tocid&doc_key=43469afc19c6e8287e459ba12297fe2e&infobase=12016 (sorry, this one wouldn't hyperlink, maybe it's too long?)
It also addresses upkeep of the structure, trimming dead branches, and other things.