The jocular Australian-English phrase the river that flows upside down and its variants denote the Yarra River, which flows through Melbourne, Victoria.
This phrase occurs, for example, in the following from The Canberra Times (Canberra, Australian Capital Territory) of Sunday 14th July 1985:
VICTORIA NOT AMUSED
[…] Trans Australia Airlines decided recently to put a bit of fun into its advertising […]. The joke fell flat in old Melbourne town, but Sydney found the new advertisements very amusing. All TAA did was to advise the Sydney business community that it had put on a number of additional northbound flights out of Tullamarine so “that you won’t be in Melbourne a minute more than is absolutely necessary”. TAA reminded customers, in the unlikely event that they had forgotten, that the best part of a business trip to Melbourne was leaving. […]
Many northerners may well be asking if TAA was not being a bit rough on Melbourne, especially so soon after Victoria had celebrated its 150th birthday. The citizens down there already have a lot to endure, such as four seasons in the one day, a river that flows upside down and a brand of football that encourages young men to rip the sleeves out of their jumpers and leap around like fairies.
ORIGIN AND EARLY OCCURRENCES
The phrase the river that flows upside down and variants refer to the brownish colour of the Yarra River, the image being that the mud is on the top, not at the bottom, of this river.
The earliest occurrences of this phrase that I have found are as follows, in chronological order:
1-: From The St George Call (Kogarah, New South Wales) of Friday 31st March 1944—however, the precise acceptation of the phrase the river flows upside down is unclear:
BEXLEY GOLF CLUB.
By Reg. Fusedale.
Once again I have been snowed in with letters from the lads in the services per favour of our Comforts Fund hon. sec., Mrs. M. Deans, whose labour of love in mailing to our boys is greatly appreciated by them and us. Lieut. Johnny Rowe’s unit was at sixes and sevens prior to a change of venue, hence the “Loots” brief missive. Says a brand new C.O. has blown in by order of the “brass hats,” and like most new brooms has been turning things downside up as it were. The only beans Johnny could spill at the moment was the new site they were going to was a beaut—here’s hoping, Johnno! Like a whiff of the past to hear from Cpl. Jimmy Cruise from the much maligned queen city of the South—“Smelbourne,” or to be exact Bonegilla, Vic., which name, of course, doesn’t sound too meaty. Don’t like the sound of his alibi for not writing. Says he has been on Q. work. Maybe on the secret list, though it sounds a bit queer to me, especially as he follows it by saying the river flows upside down—hope he doesn’t mean the Yarra.
2-: From A Melbourne Letter, published in The Cobram Courier (Cobram, Victoria) of Friday 3rd May 1946:
The Yarra has been under discussion a lot lately, most of the people praising it up above Prince’s Bridge, but one growler butts in and says it is unique amongst the rivers of the world because it flows upside down with the mud on top.
3-: From one of the unconnected paragraphs making up the column Contact, by Jim MacDougall, published in The Sun (Sydney, New South Wales) of Wednesday 23rd April 1947:
For Sydney people only: The Yarra is the only river in the world that flows upside down—with the mud on the top.
4-: From the column Peepshow, by Kirwan Ward, published in the Daily News (Perth, Western Australia) of Tuesday 6th May 1947:
Well, our just-like-California climate finally simmered down long enough for us to get that King’s Cup race over.
It’s going to be a long time before I can look a Victorian in the eye again.
Especially after all the wisecracks we’ve made over the years about Melbourne weather and the Yarra being the only river in the world to flow upside-down because it’s got the mud on top.
We’ve got to admit that Yarra-trained oarsmen didn’t do a bad job on the heaving waters of the Swan.
5-: From the column The Passing Show, published in The West Australian (Perth, Western Australia) of Tuesday 14th September 1948:
Speaking at a civic reception in Perth yesterday, Cr. A. E. Carlyle, of Melbourne, acknowledged that Perth was very clean. But Melbourne, he declared, had the distinction of being the only capital city having a river which flowed upside-down—the Yarra flowed with the mud on top. (Laughter.)
6-: From the column Many Things, by ‘the Walrus’, published in The West Australian (Perth, Western Australia) of Saturday 25th September 1948:
An “exiled” Victorian now living in Perth takes his revenge by persistently trumpeting the superiority of “good old Vic.” over any other portion of the earth’s surface. And he is not easily thrown out of his stride. The other day his attention was directed to the statement by Cr. Carlyle, of Melbourne, that that city had the distinction of being the only State capital with a river which flowed upside down—the Yarra flowed with the mud on top. “But such mud!” exclaimed the exile rapturously.