Big Muddy River The Big Muddy was not covered by the Wisconsin Glacier, about 70,000 to 10,000 years before present. However, during the melting of that glacier, the level of the Mississippi River was much higher. Water backed up into the Big Muddy Basin, forming a lake much like the artificial Rend Lake but covering a larger area. The ancient lake silted in, forming a flat bottom. After the melting of the Wisconsinan glacier, the level of the Mississippi dropped, allowing the lake to drain. A new channel formed within the old lake bed. This channel meandered in the flat bottom of the
Muddy River (Massachusetts) flows through a conduit under Route 9 and into a narrow park called the Riverway, from which it flows through three culverts: the Riverway Culvert, the Brookline Avenue Culvert, and the Avenue Louis Pasteur Culvert. The Muddy River continues from the Fens toward its connection with the Charles River via the Charlesgate area, running through a stone-paved channel surrounded by a narrow strip of parklands. In a series of stone bridges and tunnels, it passes under Boylston Street, Massachusetts Turnpike, Commonwealth Avenue, Storrow Drive, and a series of elevated connecting ramps (the Bowker Overpass). In its natural state, the outlet