Today I visited the location and was able to traverse this track from north to south. The start of the track is not at all obvious and there are some quite sketchy sections in the northern half. At all times the track remained outside the fenceline of private property. When I reached the southern end, I encountered a wooden barrier that looked like it had been constructed recently.

As the path exists on the ground, it will not be removed from OSM. However, I note that it is tagged with access=no, showing it as not available for use. (Although I don't believe the track closure sign at the southern end has any legal force, it is clear the council wishes to discourage use of the track.)

In addition, I have made the following changes to OSM:
- Corrected the location of the track, now clearly shown as following public land
- Added the wooden barrier at the southern end to the map
- Mapped the extent of the Yanggai Baring Linear Park (public land) as a separate boundary from the wooded area (which represents land cover, not land tenure, and extends over public and private land)

In the long run I hope the City of Manningham is able to develop a safe, level walking track along this beautiful gully so that all may enjoy it.

(see also the discussion at https://www.openstreetmap.org/changeset/150475304)