DemographicsLake Marmal is approximately 89.28 square kilometres. In 2016 the population of Lake Marmal was 21. The population is 56% male and 44% female. On average the monthly mortgage repayments in Lake Marmal 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.