DemographicsSwan Marsh is approximately 54.97 square kilometres. In 2016 the population of Swan Marsh was 121. The population is 55% male and 45% female. On average the monthly mortgage repayments in Swan Marsh are $800 to $999. The most common weekly income bracket is $300 to $399 per week. Weekly rents in the area are on average $150 to $199.