A koala trapped down a stormwater drain has been rescued by a good Samaritan on the Gold Coast.

A passionate wildlife carer for many years, Larry Dawson was humble about saving the stricken koala.

"It just happened, it wasn't anything heroic, it just happened," he said with a laugh.

Mr Dawson and his wife Bronwen Bell were on their nightly walk along bushland near their Coomera Waters home when one of their two poodles started sniffing a heavy water drain grate.

"I wondered why she did, so I just happened to look in and I saw what I thought was a cat," Mr Dawson said.

On closer inspection he was surprised to find a koala stuck down the three-foot drop.

Mr Dawson said the koala was about four years old and its fur was matted with leaves and debris.

"It was not happy, it had been in there for a while. How she got in there I have no idea," he said.

Mr Dawson says he grabbed the koala by the scruff of the neck and released it back into the bush. ( Supplied: Bronwen Bell )

After wrestling with the heavy iron grate for about five minutes, Mr Dawson finally prised it loose.

He reached in, grabbed the koala by the scruff of the neck and lifted it out.

"I grabbed her like a mother would ... and she started making lots of noises and whatnot," he said.

"I knew if I had to grab her I had to grab her once."

While Mr Dawson was humble about his rescue efforts, he said it was a good feeling.

"It was lovely to save its life because it definitely wouldn't have lasted another night," he said.

The koala was last seen scampering back into the bushland.