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) of the Muddy River into the tidal Charles was much wider. It formed the eastern Brookline border with Boston and Roxbury (depending on the year), from Brookline's incorporation in 1705 until Boston's annexation of Allston–Brighton in 1873. The present form of the river and surrounding parks was created by the Emerald Necklace project, between 1880 and 1900. Under the direction of designer Frederick Law Olmsted, the project reclaimed marshland, creating sculpted and planted riverbanks. The Muddy River is mentioned by John Winthrop, in his famous "Journal of John Winthrop," as the site of an unidentified flying object in March 1638