growing season. Pool 25 was never as productive in submergent growth 

 as Pool 26, but when water levels were stable, as in 1948, 1949, 1953, 

 and 1963, submerged aquatics did occur. After 1968, submerged aquatic 

 growth was greatly reduced. This was the result of 2 consecutive 

 years of severe water fluctuation and increased sedimentation and tur- 

 bidity. In their 1975 report Klein et al. (1975: 31-34) reported only 

 occasional submergent plant growth on Pools 24, 25, and 26. George 

 Pay ton, refuge manager for the Calhoun unit, Mark Twain National Wildlife 

 Refuge, reported (personal communication) that no submerged aquatics 

 now occur in Swan Lake. 



Moist soil plant production depends upon consistent low water 

 levels which expose mud flats during a minimum of 70 days between mid- 

 July and the end of September. At the Batchtown area good moist soil 

 production, predominantly wild millet and smartweeds , occurred when 

 water levels were low and stable as in 1950, 1952, 1953, and 1959. In 

 1955 water levels were initially dropped in Pool 25 by the Corps and 

 then raised throughout the growing season. This resulted in the 

 destruction of most moist soil production. 



Marsh plants, as a group, can withstand greater water level fluc- 

 tuation than other types of wetland plants (Bellrose et al. , 1977: 

 C-34). This was the case at Flat and Gilbert Lakes. By 1944, after 

 two consecutive years of flooding, most of the moist soil and sub- 

 merged aquatic plants had disappeared and only marsh smartweed at Flat 

 Lake, arrowhead at Gilbert Lake, and American lotus continued in their 

 former abundance. Yeager (1949: 55) mentions that most plants except 

 duck potato had virtually disappeared from the Calhoun Point area by 

 1945. Marsh plants are affected by fluctuating water, but to a lesser 

 extent than other wetland plants. 



The nine-foot channel project initially expanded and stabilized 

 low water levels on Pool 26. This was of benefit to most wetland vege- 

 tation as recorded by Yeager (1949: 54), Leopold (1939), and Bellrose 

 (1941: 278). However, Pool 25 was subject to frequent and sometimes 

 severe fluctuations by the Corps of Engineers (narrative reports, Mark 



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