The Colo River catches water form its tributaries. The most significant of these are:
None of these water sources are dammed so when heavy rain falls, the run off all channels its way to the Colo river and then from the Colo into the Hawkesbury River.
The propensity of the Colo River to flood is also dependant on the amont of rain absorbed in the catchment versus the amount of run off created.
The flooding in the tidal section of the Colo , lower than Wheeney Creek is also impacted by the Hawkesbury. If teh Hawkesbury is in flood the Colo cannot discharge its water as readily and the water will back up.