1. Mississippi River

2. River Facts Begins 200 miles north of Minneapolis at Lake Itasca State Park. Length: 2,352 miles Width: 20 ft at headwaters to 1 mile across Louisiana Ends in Gulf of Mexico 31 states & 2 Canadian provinces drain into the Mississippi Rive. Water discharged at a rate of 600,000 cubic ft. per second. Takes 90 days for water to travel from MN to Gulf Carries 436,000 tons of sediment each day

3. Mississippi River Basin

4. Mississippi Deltas

5. In the beginning… Red River and Mississippi River were separate rivers.

6. 15 th Century Mississippi turned west and a loop called Turnbull’s Bend was formed. Intercepted the Red River which became a tributary of the M. River. Atchafalaya formed as a distributary.

7. 1727 Construction of first levees along the Mississippi River completed.

8. 1778 Log jam at entrance to Atchafalaya.

9. 1831 Captain Henry M. Shreve dug a canal through the neck of Turnbull’s Bend and shortened river travel time.

10. 1839 Log jam at Atchafalaya is cleared. As A.River got wider and deeper, it captured more of the M. River water. When water in R. River was high and M. River low, water flowed east through Old River. When water was high in the M. River, water flowed west through Old River.

11. 1882 River levees extended from Cairo, Illinois to the mouth of the river.

12. 1928 Flood Control Act of 1928 – instructed Corp of Engineers to tackle problem of flooding in lower M. River basin. Levees, spillways, and related structures.

13. Old River 1928

14. 1931 When river reaches a critical stage, the Bonne Carre spillway is opened to allow water to flow into Lake Pontchartrain. It has been opened 10 times.

15. 1953 If river continues to rise after the Bonne Carre’ spillway is opened, then the Morganza Spillway is opened. Only opened twice so far.

16. 1963 Decision made to control flow of river so that 70% of water will go down the Mississippi River and 30% down the Atchafalaya. Old River Control Complex completed.

17. 1985 -1986 1985: Vidalia hydroelectric plant put in place north of the outflow channel. 1986: Auxilliary Structure opened.

18. Effects of Hydrological Modifications Sediment from river is not flowing through the wetlands. Subsidence (sinking) is occurring and marsh vegetation going underwater and dying. Loss of vegetation leads to increased erosion and habitat loss. Sediment from river is falling off the Continental Shelf. Saltwater is intruding into freshwater areas and killing plants.