reduces the clarity of the water, thereby limiting the amount of 

 sunlight reaching submerged and emergent aquatic plants. Turbidity 

 has extirpated the submerged aquatic plants and reduced marsh acreage 

 in the unprotected backwater areas of Pools 24-26. 



22. Sedimentation has produced extremely soft bottoms which make 

 it difficult for aquatic and marsh plants to gain or retain a root- 

 hold when exposed to wave action. Sedimentation also affects these 

 plants by physically smothering plant beds and partially filling 

 backwater areas, thus reducing water acreage and limiting the diversity 

 of habitats available for plant colonization by creating a uniform 

 bottom. 



Although aquatic and marsh plants were adversely affected, sedi- 

 mentation has filled shallow areas, creating mud flats which at present 

 exceed preproject acreage. The moist soil plants that volunteer on 

 these mud flats were benefited by increased sedimentation. 



23. The 9-foot navigation project benefited waterfowl populations 

 by creating many thousands of acres of shallow water. Increased 

 backwaters provided shallow areas which supported both marsh and sub- 

 merged aquatic plant growth. The mallard has been the principal 

 species of waterfowl benefited by the project. Canada, blue, and snow 

 geese use of the project area also has increased as a result of manage- 

 ment of habitat by states, the U.S. Fish and Wildlife Serivce, and 

 private duck clubs, to increase the production of both natural and 

 artificially-seeded food plants. However, as a result of man-made pool level 

 fluctuations during several years in Pools 25 and 26, waterfowl feeding 

 areas were degraded. 



24. Increased sedimentation and turbidity have led to the loss of 

 submerged aquatic plants in most of the project area. This loss of plant 

 food has been responsible for declining numbers of wigeon, green-wing 

 teal, and lesser scaup in the project area. In addition, increased 



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