Nebine, Wallam and Mungallala Creeks

This brochure describes the flood risk and previous flooding in the Nebine/Wallam/Mungallala Creek catchments, last updated in July 2025.

Flood Risk

The Nebine, Mungallala and Wallam Creek catchments are located about 150 kilometres west of St George in southwestern Queensland and drain an area of approximately 36,000 square kilometres. Mungallala Creek rises in the Chesterton Ranges 50 kilometres northwest of Mitchell. The Nebine and Wallam Creeks rise in an area south of a line between Mitchell and Morven. The small townships of Bollon and Mungallala are the only towns in the catchment.

All three creek systems flow in a southerly direction, parallel to each other for some 250 to 300 kilometres before crossing the Queensland and New South Wales border west of the town of Hebel. They join the Culgoa River prior to entering the Darling River system upstream of Bourke. The creeks lie in an arid area of Queensland, with annual average rainfall between 300 and 600mm, and are dry for much of the year.

Floods normally develop in the headwaters area of Nebine, Mungallala and Wallam Creeks. However, general heavy rainfall situations may occur throughout these vast catchments.

Previous Flooding

Previous flood information for the Nebine, Mungallala and Wallam Creek catchments are well documented, with river height records for Homeboin and Tomoo dating back to the 1950's.

In recent history, the catchments have seen extensive flooding particularly in May 1983, April 1990, February 1997, March 2010, February 2012 and February 2020. The flood of March 2010 produced large scale traffic disruption and residential area inundations. Flooding in 2012 led to over floorboard flooding of several houses in Bollon. There were also localised communities that required evacuation. Major flooding typically occurs during the second half of the wet season, between February and April.

The table below summarises the flood history of the basin - it contains the flood gauge heights of the more significant recent floods.

Flood Event	Bollon (m)
May 1983	1.53
Apr 1990	1.44
Feb 1997	1.47
Mar 2010	1.76
Feb 2012	1.60
Feb 2020	1.35
Mar/April 2025	1.00

 

All heights are in metres on flood gauges.

*Preliminary values subject to verification