| |
| | Mississippi River |
 | | The 314-kilometer segment of the Upper Mississippi River extending from the mouth of the Missouri River (near St. Louis, Missouri) to the mouth of the Ohio is often termed the Middle Mississippi River. |
 | | The Chippewa River, with its steep gradient, is the primary sand source for the reach of the Upper Mississippi River downstream from Lake Pepin (Nielsen et al. |
 | | The 100-kilometer reach of river downstream from the Minneapolis-St. Paul metropolitan area, for example, suffered severe oxygen depletion caused by sewage discharged into the river (Wiebe 1927; Fremling 1964, 1989), and pollution-sensitive organisms, such as burrowing hexagenia mayflies, were absent or scarce in Pools 2, 3, and 4. |
| biology.usgs.gov /s+t/SNT/noframe/ms137.htm (14566 words) |
|