People creating unauthorized hiking/ foot paths destroying vegetation, altering water flow and altering habitat.

Off Deronda Drive, manmade paths eroding hillsides
Off Deronda Drive, manmade paths eroding hillsides

Illegal activity in HGP.  These people are creating unauthorized hiking/ foot paths, that in turn destroys vegetation, alters water flow, alters habitat. There are reasons for rules, but our city does not seem to have an ability to enforce them.  Why?