Trentham is a town in the Shire of Hepburn and Shire of Moorabool local government area, Victoria, Australia. At the 2016 census, Trentham had a population of 1,180, with a median age of 55 years. Located at an altitude of 700 metres (2,297 ft), the town is 87 kilometres (54 mi) north-west of Melbourne. The Trentham area is located on the traditional lands of the Dja Dja Wurrung Aboriginal people.

The Coliban River, an inland perennial river of the north–central catchment, part of the Murray-Darling basin, is located in the lower Riverina bioregion and Central Highlands region of the Australian state of Victoria. The headwaters of the Coliban River rise on the northern slopes of the Great Dividing Range and descend to flow north into the Campaspe River with the impounded Lake Eppalock.