1. Large Rivers Chapter 20

2. Large Rivers
Important longitudinal, horizontal, vertical interactions within rivers

3. Large Rivers
e.g., FPOM - fine particulate organic matter inputs from upstream, floodplain
Heterotrophic ---- collector invertebrates fish production

4. Impacted by Human Modifications
Multiple-use conflicts
Fishing, other recreation
Navigation
Flood control
Water source

5. Impoundment
Flood control, navigation, hydropower

6. Navigation/Flood Control Aids
Dikes, levees, channel stabilization
Floodplain reduction - 90% in lower Mississippi River

7. Boat Traffic
Wave action, turbulence, sediment suspension, erosion, dewatering

8. Hydropower Hydrographs
Altered seasonal, daily flows

9. Cooling Water
Intakes, outflows
Impingement, entrainment
Heated water

10. Pollution
Sediment, PCBs, sewage

11. Flow Diversions
Irrigation, public needs

12. The Fishery - Sport Fish
Cold large rivers
Salmon, trout

13. The Fishery - Sport Fish
Cool large rivers
Walleye, smallmouth bass, northern pike

14. The Fishery - Sport Fish
Warm large rivers
Bluegill, crappie, largemouth bass, catfishes

15. The Fishery - Sport Fish
Best in unmodified reaches
e.g., Missouri River - 2 to 2.5 X more productive

16. Unmodified vs. Modified

17. The Fishery - Sport Fish
Modified reaches
Best in tailwaters (walleye, sauger), main channel border (sunfish, bass, pike)

18. Modified Mississippi River

19. The Fishery - Commercial Fish
Often same as sport fish
Conflict as sport fishing pressure increases

20. The Fishery - Commercial Fish
Typical catch in upper Mississippi River
Common carp
Catfishes
Freshwater drum

21. Mississippi River Catch

22. The Fishery - Commercial Fish
Problem - benthophagic fish
Uptake of contaminants from sediments
PCBs
Management concern

23. PCBs in the Mississippi River