The pollution protlem on the Yamhill would be of consequence 

 primarily to resident game fishes o Attendants occasionally repor't 

 seeing "large fis?i" at Government Locks„ taut it is believed that 

 very few migratory fishes enter the Yamhill at the present timso 



ko Pudding River Basin 



The Quality of the Pudding River, as revealed by a survey on 0©^^. 

 toberl, 1948, fell v/ell vrithin the tolerance limits established for 

 cold=v/ater fishes o The BOD was consistently high over the entire 

 course of this stream, but at no station was it found to be seriously 

 high. A DO of 7,1 ppn and a 5-day BOD of 1.77 ppm were recorded at 

 River Mile 10 below Woodburn~->the same station from which Dimick and 

 Merryfield reported a DO of 0.2 ppm and a 20=day BOD of 23«2 ppm on 

 September 22, 1944. The discrepancy in results may be explained, in 

 part, by the difference in water flows on the dates in question. The 

 flow on September 22, 1944 was 7B cfSo compared with a flow of 107 cfs. 

 on October 1, 1948. Pollution of the Pudding reputedly results from 

 wastes discharged from the extensive food-processing industries near 

 Woodburno The results obtained, therefore, would depend upon the 

 nature and volume of the food procAssing operations, as well as the 

 river flows, prevailing shortly before the time of semplingo 



Pollution of the Pudding River warrants ftirther seasonal study 

 in that this tributary is of some immediate ■"-and considerable poten- 

 tial-'-value to the fisheries resources of the Willamette Valley. 



1, Molalla River Basin 



The Molalla River Basin was found free from any evidence of serious 

 pollution vfhen surveyed on October 1, 1948. 



The effect upon the Molalla from seasonal pollution of the Pudding 

 should be determined as these streams converge for approximately one= 

 half mile before emptying into the main-stem Willamette. 



The Molalla is of considerable present—and of great potentials- 

 value to the Willamette Valley fisheries resources. 



m. Tualatin River Basin 



Evidence of pollution in sufficient ouantity to affect fish life 

 was found in the Tualatin River principally below the Cities of Forest 

 Grove and Hillsboro. Although the DO of the Tualatin remained above the 

 arbitrary threshold of 5 ppm throughout the entire length on September 23, 

 a DO of 5.2 ppm was found in the quiet-water reach at Scholl's Bridge. 

 The flow at Farmington Bridge (6 miles above Scholl's Bridge) was 81 cfs. 

 at the same time in comparison wi th a seasonal minimum of approximately 

 55 cfso Conditions as foixnd at Scholl's Bridge on September 23, indicate 

 a DO approximating 2o8 ppm in the reach of the Tualatin during low flows „ 



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