In the not too distant past, people could drop a penny into the Brisbane River and see it sparkling on the bottom.

That seems ridiculous now as we gaze upon the long brown waterway that snakes through the city but it's the reality and, if the right things are done, it could possibly be achieved again.

A comparison of sediment in Moreton Bay in 1970 and 2016

But while we might wish the river were a prettier colour, the implications of its hue and that of other rivers is becoming apparent further along in Moreton Bay.

A group of UQ researchers have done a study of the spread of mud and silt in Moreton Bay being dumped there by the various rivers that feed into it.