Murchison, Western AustraliaMurchison is a locality in the Mid West region of Western Australia. At the, Murchison recorded a population of 30.DemographicsAs of the 2021 Australian census, 30 people resided in Murchison, down from 62 in the. The median age of persons in Murchison was 44 years. There were fewer males than females, with 46.9% of the population male and 53.1% female. The average household size was 2 people per household.