Already long time ago there were a lot of trouble about the people with their dogs around the area of the lake Schlachtensee.
Families, runners, people who were going for a walk were more and more upset about too many dogs and the thoughtless behaviour of the owners.
In the end (after years) it has come to an enactment and dogs now are forbidden in that area.
There seem to be signs that should show that it is a no-dogs-area, but pro-dog-people coloured them, do not everyone knows about this.
And dog owners that show up there, are treated really aggressive, like they was doing something wrong.