INTRODUCTION 



The purpose of the Columbia River Stream Survey is to provide data 

 for the evaluation of each stream, or portion of stream, from the stand- 

 point of its present and potential value in relation to the maintenance 

 of the salmon resources of the Coliombia Rivero The Columbia River water= 

 shed has been divided into several survey areas or units o This report 

 covers Area IIIo 



Area III includes all tributaries entering the Colximbia on the north 

 and west sides from the Klickitat River to Grand Coulee Dam, and the few 

 tributaries entering from the east eind south sides between the Snake River 

 and Grand Coulee Dam. Also included in this report is a section in which 

 are given brief accounts of the more important tributaries above Grand 

 Coulee Dam that formerly supported r\ins of salmono Area III has been 

 divided into three separate sub-areas to cover the several sizeable stream 

 systems that are present* These sub-areas are j (l) the Yakima River, (2) 

 the Wenatchee-Entiat Rivers, and (3) the Methow-Okanogan Rivers o Other 

 tributaries are covered in upstream order in Part 1 of this reporto 



All of Area III is east of the Cascade summit, and the major streams 

 of this area originate on the eastern Cascade slopes. The great height of 

 the Cascade range, which in this section is generally between 5,000 and 

 10,000 feet in elevation, causes most of the moistixre that is brought by 

 the prevailing winds from the Pacific Ocean to precipitate on the western 

 slopes of the rangeo Only during the winter months is there any consider- 

 able precipitation on the eastern slopes, and since the greater part of this 

 area lies east of the foothills, it is largely a semi-arid plateau section© 

 The flow of water in the larger streams that originate in the mountains is 

 fairly well sustained throughout the year, but the smaller streams are in- 

 termittent or dry during the summer and early fall months « The amount of 

 winter snowfall in the mountains and the type of weather during the spring 

 months, particularly in late May and June, are the principal factors in 

 determining whether there will be sufficient water during the sximmer months 

 to supply diversion demands and still provide stream flows adequate to per- 

 mit migratory fish to reach their spawning grounds without serious delays 

 enroutCo In general, if the month of June is cool and there is much 

 cloudy or rainy weather the snow melt is delayed, and there is usually 

 sufficient water in the streams during the following summer and fall months o 



The forest cover of the area, principally conifers, is confined to the 

 mountains and foothills <> Sage brush, grasses and other small vegetative 

 forms are the only natural covering of the vast plateau sections of the 

 watershed, except for the usual willow, poplar, and alder thickets border- 

 ing the immediate vicinity of the water courses themselves© 



