If the photo had been taken a bit further back it would have shown the entrance into the Reservoir itself. That was probably at the middle of that side.

I remember the fence around it and we got in through a hole in it off the footpath to Blue House.

The building that was on the top at the SW end just cannot remember if there was a door into it, I assume it was bricked up.

When was it decommissioned?

Allan C.