Water Wheels is a story of historical fiction about two immigrant teenagers who grew up in Minnesota during the 1870s. Halvor Dahl's Norwegian family are poor Lutheran farmers who settle in the Cannon River valley of southern Minnesota. Emelia Meier's German family are Catholic merchants in the capital city of St. Paul.

Halvor and Emelia meet each other and experience adventures in all four corners of the state, traveling urban and rural Minnesota by train, steamboat, and horse-drawn buggy. Separately and together, they witness social and political changes, financial ups and downs, crimes, fires, blizzards, swarms of insects, and a comet.

Chapter by chapter, the teens meet and are affected by well-known Minnesota entrepreneurs James J. Hill, Cadwallader Washburn, Isaac Staples, and Theodore Hamm; politicians John Pillsbury, Oliver Kelley, and Ignatius Donnelly; bishop John Ireland, author Laura Ingalls Wilder, and outlaw Jesse James, in addition to others.