INTRODUCTION 



The pvirpose of the Columbia River Stream Survey has been to pro- 

 vide data for the evaluation of each stream, or portion of stream, 

 from the standpoint of its present and potential value in relation to 

 the maintenance of the salmon resources of the Columbia River. The 

 Columbia River watershed has been divided into several survey areas or 

 units. This report deals with the streams in Area IV, as shomi in 

 Figure 1. Area IV includes all tributaries entering the Columbia 

 River from the south and east in the 120 miles from the Deschutes River 

 up to but not including the Snake River* Area IV has been divided for 

 convenience into two sub-areas j Part 1 of this report covering the 

 Deschutes and John Day river systems, and Part 2 the Umatilla and 

 Walla Walla river systems. 



All of Area IV is east of the Cascade mountain range, and includes 

 a large amount of arid and semi-arid land. The diversion of large 

 quantities of water for irrigation purposes has greatly reduced the 

 sustained flows in the tributary streams* This factor together with 

 the obstructions placed in the streams as a part of the irrigation 

 facilities and the hazards to downstream migrating fingerlings re- 

 sulting from vtnscreened diversions have adversely affected the pro- 

 duction of salmon and trout. 



