On August 3, 1836, French astronomer and topographer Joseph Nicollet and his expedition met three Ojibwe and two Sauk Indians at the mouth of what is now the Sauk River. He was mapping the Mississippi watershed and recording the local names of lakes and rivers. Nicollet questioned how to write the name. The Americans pronounced it: Såkis, Sauks and Sawkis, the French: Såks or Sacs and the Ojibwe gave it a hard g sounding much like a k.
Nicollet reported following a solemn and friendly meeting the river was named for the Såkis Indians who were relocated from central Wisconsin. Read more: