Detectives from the Missing Persons Squad, together with a range of specialist resources are currently performing the “targeted search” south of Buninyong.
Aerial shots over the search zone show police sniffer dogs and officers scouring farmland and scrub.
An excavator digger is also seen clearing bushes beside a dirt road.
9News understands items have been found near the dam.
Victoria Police have asked members of the public not to attend the search.
”Police are undertaking a targeted search in the Ballarat area today as part of the investigation into the disappearance of Samantha Murphy,” police said.
“We are not in a position to supply further specific details of today’s operational activity at this time.”
Detectives said they “have been regularly undertaking a range of enquiries and small-scale searches as part of the current investigation” since Murphy went missing.
Samantha’s family has also been advised of the search.