The 2014 Spring Valley township, Minnesota, population is 468. There are 15 people per square mile (population density). The median age is 51.5. The US median is 37.2. 70.02% of people in Spring Valley township, Minnesota, are married. 5.76% are divorced. The average household size is 2.19 people. 25.49% of people are married, with children. 6.54% have children, but are single.