It has been one month since little Gus vanished from his family’s remote property.

Police will return to a rural South Australian property on Friday to drain a dam in a fresh bid to find missing four-year-old Gus Lamont — exactly one month since the boy vanished from his family’s remote sheep station.

The dam, located about 600 metres from the homestead at Oak Park Station in the state’s Mid North is roughly 4.5 metres deep and was previously searched by divers.

But authorities said on Thursday draining it will allow for a clearer visual sweep, especially in areas thick with underwater vegetation.

Police said the move is aimed at ruling out the possibility Gus may have drowned.

It follows weeks of intense ground and aerial searches, including drone imaging of the terrain surrounding the homestead.

Investigators say the footage has so far failed to uncover any clues. A broader aerial survey — extending up to 10km from the property — is still underway and expected to take several weeks.

Gus was last seen around 5pm on Saturday, September 27, playing on a mound of dirt near the homestead, about 40km south of Yunta.

When his grandmother called him in just 30 minutes later, he was gone.

The search for missing August Lamont has been the largest in SA history. Credit: 7NEWS

What followed was one of the largest search operations in South Australian history. Police, SES volunteers and the Australian Army scoured more than 60,000 hectares of rugged terrain.

A second week-long search earlier this month also failed to turn up new leads.

The only clue remains a single footprint found on September 30, just 500 metres from where Gus was last seen.

Experts say the search is now considered a recovery effort, with survival unlikely given the harsh climate and lack of water, food or shelter.

However, new theories suggest Gus may have travelled further than previously thought.

Human physiology expert Nina Siversten from Flinders University told 7NEWS Gus could have covered three to eight kilometres over three days.

“Fear would be an absolute factor,” she said, adding that it could impact his ability to move or seek shelter.

Former SES volunteer Jason O’Connell, who walked the property with Gus’s father, said the case “defies logic.”

“It’s been searched. Gus is not there,” he told 7NEWS.

Hundreds of people have joined in the massive land search to recover August Lamont Credit: 7NEWS

Police have said there’s no evidence of foul play.

Gus’s mother and a grandparent were tending the flock at the time, while Gus was with his grandmother and younger brother Ronnie. His father reportedly lives off the property.

Drone footage using infrared technology is still being assessed. While no further searches are currently planned, detectives haven’t ruled out returning.

“There is still work that is ongoing by SA Police,” Premier Peter Malinauskas said.

“They are continuing to make inquiries.”

Gus has long curly blond hair and was wearing a blue long-sleeved Minions T-shirt, a grey sun hat and boots when he went missing.

Anyone with information is urged to contact police.

CRE: http://7news.com.au/news/dam-to-be-drained-as-police-return-to-the-search-for-missing-gus-lamont-on-south-australian-property-c-20517649