Varied journey through farmland and forest areas.
Flat, dry and hot... you will actually be "out the back o’Bourke" in some of the most remote parts of north western NSW.
The Balonne River starts where the Condamine and Dogwood rivers join around halfway through the most remote section of the section between the small towns of Condamine Township and Surat (~200 km) in QLD; that is in turn halfway between Chinchilla and St George (475 km).
The Culgoa River starts about a day's paddle from St George as a distributary of the Balonne that channels off almost all of the water under non-flood flow. The Balonne technically finishes downstream at the Ballandool - Bokhara split, though often this section is known as the Balonne Minor River. You cross the border while paddling the Culgoa River.
The Barwon and Culgoa Rivers meet to form the official starting point of the Darling River.
Surat is a small country town with a general store.
The Balonne River is generally deep and wide with some narrower sections on good flows before a decent day's paddle along Lake Kajarabie. On a low flow, expect to fight through a significant number of log jams.
When Lake Kajarabie is filled, the waters extend a long way up to around Wycombe. Below the dam there are some fairly shallow rocky sections just before the flat waters created from St George Weir. This would likely be impassible with a very low flow.
What way to go????
I had initially thought the Bokhara River was the best choice as it has multiple small towns that could be used for supplies, but the Culgoa River appears to have the best overall flow when there is water. The Bokhara River appears to be mostly dry outside of flood events.
Culgoa River is 489 km long and rejoins the Barwon River to form the Darling River. It did have a store about half way at Weilmoringle but this is now closed. Even after joining the Darling River you still have 108 km to go to get to Bourke. This means that you will be faced with a 600 km leg without supplies unless you organise a food drop somewhere along the way.
The Birrie River flows from the Bokhara River back into the Culgoa River and the fourth major river distributary of the Balonne River, the Narran River, flows into the ephemeral (temporary) and endorheic (closed, no outlet rivers) Narran Lake.
In a pinch you could walk over to one of the towns along the Bokhara River. If you are lucky you may even have some luck with a passing car.
Small store. ~100 km downstream from Dirranbandi if on the Bokhara River (a super rough estimate). This is 28 km along Woolerbilla Rd if taking the Culgoa River, about 123 km from the rivers head.
Both Hebel and Dirranbandi are on the St George to Lightning Ridge bus route.
Gauges at the border, or see the BoM Northwest Rainfall and River Conditions Map.