Hmmm, maybe the bear encloser was built and opened in 1985/6, given what I found in Age articles re: Peter Evans. The "waterfall and a double-sized Olympic pool" sound like the bear exhibit (though I don't know if the moat is double Olympic sized

).
If opened in 1986 probably explains why I don't remember it always being there.
The enclosure for the badgers was across from the lions between the entrance & exit for the covered/indoor viewing area, correct?
July 17, 1984
...Three years ago, the zoo opened its first public appeal, with actress Lynda Stoner and a cast of extras in cuddly bear suits, imploring the public to pay up and be bear lovers. The intention was to move the bears from their concrete pits into a more aesthetic environment with trees, shrubs and rock pools. On paper, the polar bears were promised a waterfall and a double-sized Olympic pool. Unfortunately, Senda, Oscar and Ronald will not see this grand plan realised. The three polar bears are dead.
Sep 19, 1985
...Reprinted on the box is a quote from Barry Hill, who wrote in Green Guide: "(Evans) was the supreme bear with the sore head, but he was a warm bear." Rather fittingly, proceeds from the sale of the cassette will be used to support the building of a new bear exhibit at the Melbourne Zoo. Evans loved the zoo, to be sure, and would nave appreciated such exquisite irony.
May 7, 1986
...pop single and raised $50,000 to build a five-star bear enclosure at the Melbourne Zoo. And now (ta-ran-ta-rah!) comes an 'Evans, the Wireless Scrap book', featuring pictures and words about the career of Melbourne's late and lamented favorite breakfast-time raadio grump,