Ur.ited States Department of the Interior 

 Oscar Lo Chapnan, Secretary 

 Fish and Wildlife Service 

 AlhertMo Daj', Director 



Special Scientific Report - Fisheries 

 NOc 41 

 OXYGEN BLOCK IN THE MAIN-STEM WILIA^TETTE RIVER 



By 



Frederic F. Fish 

 In Charge, Western Fish-Cultural Investigations 



and 



Richard A. Wagner 

 Biological Aid 



CONTENTS 



Page 



Fore^ftard. oa»oo.oo 1 



mtrOQUO ttLOn ooooooeoo***oe»ooft»*»«»ft* 3 



1S49 Main-Stsm Wilianette River Studies 5 



iiirerpretation of Results 13 



Ccnolusions oo>.oo.a.« 17 



Litsraturs Citedo o».<i...«o.... 18 



