Paramedics were called to the pool about 4.35pm and said the girl was taken to Albury Hospital.

A witness said the girl appeared to be aged about three and the accident was frightening to watch.

The woman was sitting on grass behind the waterslide stair cage when she saw the girl falling.

"It was the sound of the first thump that drew my attention to it," she said.

"It was surreal –  I can only assume she fell from the second level down onto the first level, she definitely hit her head.

"I heard a few more thumps and then she was at the bottom, lying on the pavers screaming."

The woman said several people, including lifeguards, rushed to the girl’s aid and an ambulance was called.

She said the little girl was then carried towards the first-aid room. 

The entry door to the waterslide was immediately locked by pool staff and re-opened on Thursday.

“The accident was horrific to see. It's any parent's worse nightmare and I really hope this little girl will be OK,” she said.

Pool manager Paul Tanner said his main concern was for the girl's health and well-being.

“At the moment. we are investigating what happened,” he said. “The main thing is we want to make sure the young girl is OK.”

Albury Council director of community and recreation James Jenkins said council would support pool management as required.

“We extend our wishes for the little girl to have a speedy recovery,” he said.

He would not say whether further safety measures on the stair \way would be implemented.

At other Australia Day hotspots Albury SES, St John's Ambulance and the Albury and Border Rescue Squad all reported a quiet day.

St John's area manager Helen Chant said teams at Noreuil and Wymah came across no serious incidents. 

“It is still really hot most days, so remember sunscreen and to keep up water intake,” she said.