Table 6. — Concentrations of DDT and DDE in materials collected from test and control streams on 

 June 18 and 21, 1963, after spraying. Prince of Wales Island, Alaska 



[Trace, <0.005 p.p.m. in water, <0.02 p.p.m. in fish and clams] 



■■• The water in Old Franks Creek contained a trace of DDT on June 18, 1 hr. after spraying 

 began. No other samples were taken. 



All intragravel water sampled in Cabin Creek 

 (test streann) and Old Tom Creek (control) 

 contained only traces of DDT. In other studies, 

 flushing of DDT from sprayed drainages has 

 been found to be highly irregular. Concentra- 

 tions of DDT toxic to fish (greater than 0.05 

 p.p.m.-- Alderdice and Worthington, 1959) were 

 still present in a British Columbia stream 

 12 days after an application of DDT at the 

 rate of 1.12 kg. per hectare (Crouter and 

 Vernon, 1959). In Montana, Grahann and Scott ^ 

 found that most of the DDT applied to the 

 watershed at 1.12 kg. per hectare soon dis- 

 appeared from the stream water; 32 hr. after 

 spraying the concentration was less than 

 0.01 p.p.m. Cope and Park,'' at the same 

 application rate, found no DDT in the stream 

 27 hr. after the spraying. 



^ Graham, Richard J., and David O. Scott. 1959. Effects 

 of an aerial application of DDT on fish and aquatic insects 

 in Montana. Mont. State Fish Game Dep., U.S. FishWlldl. 

 Serv., and U.S. Forest Serv., Final Rep. 1957 and 1958, 

 35 p. 



"^ Cope. Oliver B., and Barry C. Park. 1957. Effects of 

 forest insect spraying on trout and aquatic insects in some 

 Montana streams. U.S. Fish Wildl. Serv., U.S. Forest 

 Serv., and Mont. State Fish Game Dep., Progr. Rep. 1956, 

 56 p. 



POSTSPRAY OBSERVATIONS 



The first postspray rainfall (about 0.8 cm.) 

 occurred over Skowl Arnn on the morning of 

 June 23, 1963. To determine if DDT was 

 leaching or washing into the streams fronn 

 the treated watersheds, four samples of water 

 were collected from each stream at 2-hr. 

 intervals after the rain began. Trout were 

 collected from the cages at the mouth of 

 each stream that afternoon. Only trace amounts 

 of DDT were found in the water samples and 

 in the fish samples, except for fish from 

 Virginia Creek (table 7). In the trout from 

 Virginia Creek the concentrations of DDT 

 and DDE had increased from "trace" 

 (<0.02 p.p.m.) to 0.02 and 0.03 p.p.m., re- 

 spectively. Neither Cope and Park (see foot- 

 note 7) nor Graham and Scott (see footnote 6) 

 found increased levels of DDT in streams 

 after the first heavy postspray rainfall. 



The first postspray assessment of aquatic 

 insects was made on June 24. No insects 

 were found on the tagged stones in the test 

 streams. Cabin and Virginia Creeks (figs. 3 

 and 5). Additional stones were examined care- 

 fully in each sprayed streann from the nnouth 

 to the lake; although a few water mites 

 (Hydracarina) were observed occasionally. 



10 



