How deep is the Brisbane river?

From 13 meters at the mouth to 4 meters at the Bremer Junction....

*According to a document at the University of Queensland, the Brisbane river reaches it's deepest point around the 'Indooroopilly bridge' in 25m intervals maxing out at around 30 meters deep in a large underwater gorge.

However "From 13 meters at the mouth to 4 meters at the Bremer Junction...." , the original answer is quite accurate if one were to predict the average depths of the river.

Source: espace.library.uq.edu.au/eserv/UQ:10885/sargent-dgp-8-2.pdf