Table 1:--DDT reaching the water surface, 

 pounds per acre 



0.029 pound per acre of DDT reached the water 

 in 1959; in 1960, only a trace penetrated to the 

 water surface. This decrease from the 1959 

 concentration may have been partly due to a 

 more advanced growth of vegetation. 



In the Brasstown Bald area, spray cards 

 indicated that 0.16 pound per acre of DDT reach- 

 ed the surface in 1959 and 0.09 pound per acre 

 in 1960. Increased density of foliage in 1960 

 may have affected the deposition here, too, al- 

 thougti reductions were measured in the open 

 areas as well as the vegetated plots . 



E>rift samples (tables 2 and 3) indicated 

 very little increase in numbers of dead and 

 dying invertebrates drifting downstream after 

 the spray in the Conasauga Lake creek in 1959 

 and 1960. Drift samples in the creek at Brass- 

 town Bald, on the other hand, indicated large 

 increases in affected stoneflies, mayflies, 

 noterids, and limnephilids from pre-spray to 

 post-spray times in 1959 (fig. 2). Smaller 

 increases were noted in 1960. Increases in 



numbers of affected terres- 

 trials were relatively higher 

 in 1960 than in 1959. Both 

 1959 and 1960 drift samples 

 showed that different groups 

 of aquatic organisms were 

 affected by the DDT to dif- 

 ferent degrees. Those that 

 were affected showed signs 

 of distress within the first 

 hour . The greatest number 

 of dead or dying insects were collected one -half 

 hour after the application at Brasstown Bald, and 

 by the fourth hour after spray time the numbers 

 had decreased 85 percent in 1959, Few insects 

 appeared in the drift sample after 24 hours . 



-450- 



E 



D 400 



I960 



3 4 



after treatment 



Figure 2. --Number of mayflies and stoneflies 

 taken in five -minute drift samples in a stream 

 on Brasstown Bald. 



Table 2: --Numbers of organisms taken in five-minute drift samples 

 from a stream near Conasauga Lake 



