Colac population Migrants push up Colac’s population, just a little Colac’s population has crept up marginally in the past year, mostly thanks to overseas migration. By David McKenzieApril 22, 2020 Changes to Colac growth plan Two Elliminyt property owners have swayed Colac Otway Shire Councillors to change a 30-year Colac growth plan to better reflect how they want to develop their land. By A Staff ReporterMarch 22, 2019