Colac /ˈkoʊlæk/ is a small city in the Western District of Victoria, Australia, approximately 150 kilometres south-west of Melbourne on the southern shore of Lake Colac and the surrounding volcanic plains, approximately 40 kilometres (25 mi) inland from Bass Strait. Colac is the largest city in and administrative centre of the Colac Otway Shire. At June 2015, Colac had a population of 11,817. A commercial centre for a major agricultural district, it was named after nearby Lake Colac and was proclaimed a city in 1960.