Michigan. Lower Wisconsin The lower Wisconsin River flows through glacial drift until it enters the Driftless Area and eventually reaches the Mississippi River. It extends about 116 river miles (187 river kilometers) from Portage to its confluence with the Mississippi River, falling from about elevation above sea level (msl) at Portage to , msl at the Mississippi. The reach has nearly uniform hydraulic gradient of about 1.5 feet per mile (0.3 m/km). There is only one major tributary, the Kickapoo River, which enters just before the Mississippi at about River Mile 16 (River km 26). Since there are no major tributaries, river discharge in the reach are relatively constant, averaging about at USGS gage 05407000 at Muscoda. The river channel is dominated by sand. Sand bars, tow-head islands and new, multiple channels form often and constantly change. The channel is wide and shallow. The Portage The portage at Portage, Wisconsin is not unique as a passage between the Great Lakes and Mississippi River watersheds. Similar passages exist all along the watershed divide, for instance, at Chicago and in the northern Indiana area. What is unique is that, while the Fox is a small stream—typical of such passages—the Wisconsin is a large river, already over long. The divide between the two rivers has little grade change, although it is marshy. The Wisconsin occasionally flowed across the Portage into the Fox during high water. The Fox and Wisconsin have modified their courses and outlets over geological time and it is likely that either river has flowed into either watershed. Only about separate the two rivers. The Fox River end of the canal is at about elevation msl. The Wisconsin River end is slightly higher, depending on Wisconsin River discharge levels. The Portage lies about 116 river miles (187 km) from the Mississippi River and 162 river miles (261 km) from Green Bay. Upper Fox The upper Fox River flows northwest from its headwater to within the Portage. It then flows to the north-northeast to the Lake Winnebago Pool. It extends about 110 river miles (177 km) from Portage to Lake Winnebago, falling only about from elevation , msl at the Portage to , msl at Lake Winnebago. The reach has a shallow grade. The hydraulic gradient averages about 4 inches per mile (0.06 m/km). There are two very shallow lakes along the way, Buffalo Lake and Puckaway Lake. The river drainage area