trendily solving the wrong problem
On the previous mention of hiring more rangers: Think. Think hard. You have a bunch of people with cameras in their phones, playing a silly AR game. So let the parks department run their own game! $20 (or whatever) for footage of littering or whatever property damage, posted to some SMS recipient, who is a person with some bit of authority who can go to where the problem is instead of having to be everywhere (i.e. numerous). Spend the taxes on putting up signs with 2 messages: one is a strict warning against creating a problem and obviously some mention of a fine. The other is about a bounty for providing evidence of someone creating a problem and the number where you'd send it. Anyone can avoid the fuzz but when some careless folks see the 2nd they ought to realize that they are surrounded by cameras. For Future Sanity, the fines cover the bounties.
State Employee used creative problem solving. It's super effective! (well, at least in a parallel reality I've been spying on with my imagination...)