Prairie Lake Township is located in the southwest part of Saint Louis County.

The northern and west–central portions of Prairie Lake Township are located within the Savanna State Forest.

There were 46 housing units at an average density of 1.3/sq mi (0.5/km2).

[1] Of the 20 households 35.0% had children under the age of 18 living with them, 55.0% were married couples living together, 15.0% had a female householder with no husband present, and 25.0% were non-families.

There were 31.3% of families and 32.9% of the population living below the poverty line, including 46.3% of under eighteens and none of those over 64.