Detectives from Fawkner Sexual Offences and Child Abuse Unit arrested a man following an ongoing investigation into a historical indecent assault.
The incident is alleged to have occurred at a swimming pool in Sunbury sometime in the summer between 1984 and 1986.
It is believed the man, aged in his 40s at the time, indecently assaulted the victim who was a child at a pool on Ligar Street.
The man, now aged 79 from Bendigo, was interviewed by detectives on 1 July and is expected to be charged on summons with indecent assault.
The investigation remains ongoing and police are continuing to look at any possible links to other matters.
Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report at www.crimestoppersvic.com.au