Big Muddy River
| Big Muddy River | |
|---|---|
Aerial of Jameson Island in the Big Muddy, view looking south. Credit:US Fish and Wildlife Service
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| Basin features | |
| Main source |
Jefferson County southeast of Centralia, Illinois 38°28′27″N 89°05′25″W / 38.474216°N 89.0903471°W |
| River mouth |
Confluence with the Mississippi River southwest of Murphysboro, Illinois 341 ft (104 m) 37°34′25″N 89°31′01″W / 37.5736608°N 89.5170413°WCoordinates: 37°34′25″N 89°31′01″W / 37.5736608°N 89.5170413°W |
| Progression | Big Muddy River → Mississippi → Gulf of Mexico |
| Physical characteristics | |
| Length | 156 mi (251 km) |
| GNIS ID | 404425 |
The Big Muddy River is a 156-mile-long (251 km) river in southern Illinois. It joins the Mississippi River south of Murphysboro. The Big Muddy has been dammed near Benton, forming Rend Lake.
The Big Muddy has a mud bottom for most of its length.
The Big Muddy drains a 2,344-square-mile (6,070 km2) watershed. In 1995, water quality was assessed as "fair" to "good". Pollution sources include agricultural practices, mining and municipalities.
The watershed of the Big Muddy was covered by the Illinoian Glacier about 300,000 to 132,000 years before present. The Big Muddy basin formed after the retreat of that glacier.
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 Wisconsinan-era lake. This is why the Big Muddy tends to be so muddy.
The Big Muddy joins the Mississippi River in Jackson County near the La Rue-Pine Hills Ecological Area and less than 1 mile (1.6 km) south of Grand Tower Island. The Pine Hills are bluffs overlooking the Big Muddy as it flows through La Rue swamp. During the melting of the Wisconsinan glacier, the Mississippi River flood plain was filled with rushing meltwater in summer. During the winter the flow of meltwater was cut off, and the floodplain was a wide stretch of exposed mud. Winter winds created dust storms that covered Southern Illinois with "loess", fine grained, wind born deposits. At the edge of the floodplain, dunes, called "loess hills", formed. The Pine Hills are loess hills standing several hundred feet above the floodplain.
Prior to the construction of Rend Lake, much of the ancient lake bed was swamp: a forested area that was covered by water through most of the winter, and during wet summers. When the Big Muddy flooded, the water covered the flat bottom of the ancient lake bed for miles either direction from the meandering channel.
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Wikipedia