Intensive searches at Oak Park Station, in South Australia's Mid North region, have failed to find any trace of Gus Lamont, who disappeared on September 27.
On Friday, SA Police drained the 4.5m-deep dam, which is 600m from the homestead.
The operation to drain the dam started at 9.15am and took about three-and-a-half hours, pumping water at approximately 15,000 litres per minute.
A total of 3.2 million litres of water was removed from the dam.
"Police divers have thoroughly searched the main dam and the holding dam, including clearing of weed beds, however, there was nothing of significance found," police said in a statement.
The water was then pumped back into the dam.
An initial 10-day air and ground search at the property, about 40km south of Yunta, was one of the largest undertaken by SA Police, and the initial area covered an estimated 470 sq km.
The most recent operation, a four-day search within a 5.5km radius of the homestead earlier in October, concluded without any evidence being located.
Earlier this week, police said further aerial imaging within a 10km radius of the homestead would take several weeks to complete.
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