The Willamette Valley is a highly productive agricultural area ap- 

 proxinately 200 miles long and 20-AO miles wide,, Since the valley has 

 a very slight gradient^ it alvrays has been subject to flood and drain- 

 age problems c The Cascade Mountains particularly intercept moisture 

 laden air masses brought by prevailing westerly winds I'rom the Pacific 

 Ocean, causing heavy rainfall in the spring and fall months and heavy 

 snowfall in the vidnter months on the western slopes of these mountains « 



The Willamette River has an extensive triV)utary systemo Because 

 :)f their larger .^size and sustained floras, the tributaries origiiiating 

 in the Cascades are more important to migratory fish and niany of them 

 formerly supported very large runs of salmon and steelhead trout, o 



The streams entering the Willamette from the Coast- Range apparently 

 never have been of any great importance to migratory fisho The fall 

 Chinook run apparently never passed above V/illamette Falls ^ but spawned 

 in and possibly below the Clackamas River. A smp.ll n'omber of silver 

 salmon still enter the Clackamas, Molalla, and T'ualatin Rivers o A good 

 run of spring chinook salmon, comprising a significant part of the badly 

 depleted spring run of the Columbia, enters the Y/illamette from l*iarch to 

 early June» These fish enter nearly all of the streams arising on the 

 Cascade Mountain slopes and remain in large, deep resting pools until 

 the time of spawning, Y/hich usually begins with the first fall rains » No 

 chum or blueback salmon are found in the Willamette River system* A 

 fair run of spring steelhead trout still ascends some of the tributaries o 



Of all the adverse factors contributing to the depletion of the 

 former great runs of anadromous fish in the 1/illamette River, pollution 

 is the most important. The rav; domestic and industrial wastes dis- 

 charged into the river from one end of the V/illamette Valley to the other 

 have, in addition to their inherent toxic affects, such a biochemical 

 oxygen demand that except during flood or freshet stages the lower reaches 

 of the river are virtually devoid of oxygen. The lack of oxygen acts as 

 a barrier to the passage of both upstream and dovnistream migrating fish, 

 and is responsible for the disappearance of the fall runs of salmon in 

 this system. 



• The pollution load carried by the ?/illamette River is better com- 

 prehended T^hen it is considered in terms of population and numbers of 

 contributing industries. According to the 19'i.O census the population 

 of the i/illamette Valley was 686,011. This population has greatly in- 

 creased in recent years, especially in the Portland area-. The Oregon 

 State Planning Board found in 1937 that of the 1<,637 industrial estab- 

 lishments in the State, 853 were located in the Willamette Valley. These 

 included 7 pulp and paper mills, LH canneries of all kinds., 270 sawmills, 

 4 flaxretting plants, hl^ laundries, 3 gas vrorks, 20 mines, 9 Trroclen mills, 

 and 66 others. Gleeson and Merryfield (1936) estimated that the waste 

 products from just the four pulp mills located at Oregon Citj/ had an oxygen 

 deciand equal to "a population of 489^000 persons". The greater part of the 

 waste products of the human population and the industrie,3 is carried by the 

 Willamette River o 



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