When we first moved into our home, we used to walk on one of the paths in the canyon during the afternoon for exercise.
When we came upon smaller camps that were unoccupied but filthy and littered partly with empty alcohol bottles, we ended our walks.
Later, it was publicized that at the other end of the canyon, where a larger camp was, prostitutes were filmed entering and leaving the camp. The Minute Men tried get in there and clear the place out and local police stopped them.
I'd tell the police to clean it up or the city would be sued. It's a hazard, both medically and lawfully.