Keith_A (Qld) replied:

Hi Russ - we were there 2 weeks ago, and while there was a good flow over the causeway it was no problem for our group of 3 vehicles + campers & vans.
( An unloaded subaru forrester even went across - very brave/experienced or very foolish).

Road to Coongie lakes is well graded sand/gravel. Some sections have moderate corrugations but nothing serious. (The track into Cullyamara Waterhole near Innamincka was far worse). Keep the UHF on, as the sandhills hide oncomming traffic till you are face to face. Many use channel 10.

Flow into Coongie lakes was very good, with the shoreline reducing by aprox 1.5m per 24 hrs. (Yes the land is flat, but given the surface size of the lake, that is an impressive increase.)
There is only aprox 5 campsites in the 'camping area' near the pit toilet, however several campers took the 4wd track around the lake to camp. That track has some deep sand but again no problem (just drop tyre pressure).

The campgrounds a the town common (Innamincka) is a good place to stop, and if you arrange to be there on a Sunday, the dinner at the pub is worth going to.
.........................regards..........Keith