Extract from ABC News
Last year, Lake Eyre had its most substantial fill of water in decades, but this year there could be even more. (ABC News: Tom Hartley)
For the second year in a row, an inland sea is making its slow journey through some of Australia's driest country to its home in the heart of South Australia.
Not only is every major catchment that drains into Kati Thanda-Lake Eyre already wet, more rain is forecast and there is plenty of water yet to arrive from upstream.
If this water fills Australia's largest inland lake — after getting tantalisingly close last year — it could be just the fourth time that has happened in 160 years.
Where is the water coming from?
The Kati Thanda-Lake Eyre Basin is fed by a network of inland creeks and river systems across 1.2 million square kilometres, more than five times the size of Victoria.
It's the fourth-largest catchment in the world that does not drain into the ocean.
Made up of key river systems including the Georgina, Diamantina and Thomson-Cooper, all the water caught in the catchment drains towards the middle of Australia.
A swollen section of the Georgina River system, called Eyre Creek, spills into flood country near Bedourie this week. (Supplied: Diamantina Shire Council/Valeri Fernandez)
These extensive multi-channel systems in Western Queensland can be shallow or bone-dry during the off-season, but spring to life during flooding rains.
Desert Channels Queensland operations manager Geoff Penton said those large "slugs of water" moved incredibly slowly across channels and flood plains.
"It literally takes weeks because we're talking about river systems that can be a thousand kilometres long," Mr Penton said.
For example, the 550 millimetres that inundated Lake Nash Station in the Northern Territory last weekend feeds into the Georgina River between Urandangi and Bedourie.
A flood that cut off Winton in early January took a month to move down the Diamantina River and reach Birdsville in mid-February.
As storms dump rain across the basin, water caught in major catchments are funnelled towards Kati Thanda-Lake Eyre. (ABC News)
Mr Penton said flooding was not unusual, but the scale was sometimes extraordinary.
"What you'll see is a reasonable flood event, probably two years out of 10, and then a minor flood for another couple of years out of 10," he said.
"And then Lake Eyre might fill up from a big one every 15 to 20 years."
Will Kati Thanda-Lake Eyre fill to the brim?
It's too early to say, but many locals who have lived in the area for decades are hopeful.
That's because this season is shaping up to be very similar to the conditions that set a record depth of 6 metres at the salt lake in 1974, five decades ago.
"Last year, for example, they had huge rains in Queensland, but they didn't have very much local rain around to fill it up better," resident Bobby Hunter said.
The Yankunytjatjara man was 18 when Kati Thanda-Lake Eyre had its record-breaking fill and has been waiting for another event like this for decades.
Flooding at Lake Nash Station last weekend left only treetops visible. (Supplied: Erin Gibson)
A "double whammy" of good rain seasons over 18 months was enough to fill the enormous lake in 1974.
"The lake was actually overflowing and backing up these creeks, 25 kilometres back up the creeks," Mr Hunter said.
He said many who witnessed the 1974 and 1950 floods believed the wet conditions now were "equal" to what they saw 50 years ago.
Bobby Hunter says many locals believe the wet conditions now are similar to the record-breaking 1974. (ABC News: Sarah Maunder)
Tourism operator Trevor Wright said Kati Thanda-Lake Eyre was currently about 1.3 metres deep, left over from last year's floodwaters from Western Queensland.
But unlike last year, Mr Wright said local rains had already filled many local creeks.
A slow-moving tropical low above the Simpson Desert dumped hundreds of millimetres of rain over the past week.
A time lapse between 18 January and 24 February 2026 that shows local rain beginning to fill Kati Thanda-Lake Eyre. (Supplied: NASA)
"I think 98 per cent [of water] in a normal year comes out of Queensland, Northern Territory, and this year … I would say about 50 per cent of it has come locally," Mr Wright said.
He said follow-up rains would bring plenty of wildflowers, pelicans and "tinges of green" across the desert country and wetlands of the Kati Thanda-Lake Eyre Basin.
"The rainfall we're now seeing in the catchment, especially in South Australia, that is really uncharted territory,"he said.
Are floods good or bad?
Mr Penton said the Kati Thanda-Lake Eyre Basin was meant to flood and that many regions had relied on "beneficial flooding".
"Some people might think, 'How could that be possible — aren't floods bad?'" he said.
Many native grasses with roots metres deep only grow after significant floods, and wildlife such as birds and fish rely on floods to breed.
"We have big floodplain areas, big flat country, where the grass growth, the biodiversity and the grass for agriculture rely on periodic flooding," Mr Penton said.
Desert reptiles and mammals, including kangaroos, will "turn off" their breeding cycle when it is dry until enough suitable food grows.
Mr Penton said about 70 per cent of the region had benefited from flooding rains this season, while the rest had "copped" more damage or had missed out entirely.
The Georgina River was almost dry in late 2025. (Supplied: Desert Channels Queensland)
"It really is a two-edged sword, all this rain," he said.
"There's definitely been areas where the flooding has gone beyond beneficial to damaging, where we've had just that little bit too much rain and too intense in some parts, particularly the northern parts of the region.
"But for those people who have not suffered livestock losses because of flooding, it's actually been two pretty good years and two fantastic years."
