The Diamantina River has risen, blocking off southern access to Birdsville — and the weather bureau is warning of more rain to come.
Dozens of marathon runners took part in the Simpson Desert Ultra on the weekend in the township just north of the South Australian border with Queensland.
Some travelled to Birdsville in a flatbed truck on Saturday, after sleeping in their cars on the other side of the river before the competition.
Local police officers helped participants, who had to wade through floodwaters and road closures to get to the start of the race.
But the river rose quickly overnight and many people were left with limited ways to leave the township.
SES boat to the rescue
Ultra-marathon participant Michael Bertram told ABC Eyre Peninsula the Diamantina River had unexpectedly rose since they arrived in Birdsville.
"People thought they could get across the river in a boat; they now can't get out past Windorah because that's flooded," he said.
Mr Bertram said the State Emergency Service deployed its boat to ferry about 20 participants back across the river this afternoon.
"The town's never flooded in June, as far as they can remember," he said.
Birdsville Hotel general manager Ben Fullagar said Birdsville remained accessible via road from the north, or via the airport.
"Some are choosing to hang around. With a cold beer, they are in no hurry to leave," he said.
"Some are waiting around for the water to recede."
River levels to remain high
The Bureau of Meteorology is predicting the Diamantina River will continue to rise.
A moderate flood warning was issued for the river between Birdsville and the Goyder Lagoon in South Australia, with the Diamantina River reaching 6.89 metres and rising in the town.
Road access to the Birdsville township from South Australia is currently closed.
River levels are expected to remain high for the rest of the week, as floodwaters continue to flow from upstream.
Birdsville was cut off by floodwaters after a huge deluge in February.
