Big rivers typically get the credit for being powerful and mighty, but a sweeping national study released today shows that when it comes to pollution control, even little streams can pack a punch.

Hundreds of Emerald residents are being allowed to return to their homes today as flood waters begin to recede in the central Queensland township.

Authorities at Emerald in Queensland's central highlands are keeping a close watch on the flooded Nogoa River which is expected to peak this afternoon.

Queensland Emergency Services Minister Neil Roberts flew into the central Queensland town of Emerald last night to be briefed on the latest flood situation.