NSW SES crews saw the animal jumping through the Lachlan River in Forbes earlier today.
9News reporter Hayley Francis said it took more than 40 minutes for the wallaby to swim through the river.
She said the SES crews were conducting routine checks and a reconnaissance mission on the river.
It comes as Forbes has been hit by slow-moving floodwaters with the peak still to come.
The SES has been patrolling the flooded Lachlan River, but while floodwaters have crept up to some houses in Forbes, damage to urban property has so far been minor.