[10] The township contains a coastline along the southern arm of Lake Charlevoix.

As of the census[2] of 2000, there were 1,844 people, 670 households, and 517 families residing in the township.

There were 947 housing units at an average density of 30.8 per square mile (11.9/km2).

18.7% of all households were made up of individuals, and 8.5% had someone living alone who was 65 years of age or older.

South Arm Township is served by two separate public school districts.