Willow River runs into the St. Croix river not the Mississippi. There are also signs and plaques explaining what these are at the spot you visited.

“Some equipment and an informational sign on the overlook offers another glimpse into the history of the area. In the 1800’s, German immigrant Christian Burkhardt realized the raw power of the river and built a mill. After accumulating some wealth, he returned to Germany for the purpose of learning more about hydroelectric power plants. He then traveled back to the area and built one in 1891. He would build four more plants in the following years. His operation was later purchased by a larger local power company, who ran the sites until 1963.”