The Baraboo River is a tributary of the Wisconsin River, in south-central Wisconsin in the United States. Via the Wisconsin River, it is part of the watershed of the Mississippi River. The Baraboo River also has one of the longest stretches of free-flowing river in the United States, with the removal of four dams in the 1990s leading to 112 miles of unimpede…The Baraboo River is a tributary of the Wisconsin River, in south-central Wisconsin in the United States. Via the Wisconsin River, it is part of the watershed of the Mississippi River. The Baraboo River also has one of the longest stretches of free-flowing river in the United States, with the removal of four dams in the 1990s leading to 112 miles of unimpeded river flow.