DemographicsMount Lonarch is approximately 69.98 square kilometres. In 2016 the population of Mount Lonarch was 42. The population is 47% male and 53% female. On average the monthly mortgage repayments in Mount Lonarch are $0 to $299. The most common weekly income bracket is $300 to $399 per week. Weekly rents in the area are on average $0 to $74.