phytoplankton bio-assay, light levels were kept adequate to enable 

 photosynthesis, and may have been partly responsible for such stimu- 

 lation. In nature, however, reduction of light by turbidity would be 

 expected to depress photosynthesis. 



Bio-assays carried out with juvenile pink salmon did not show 

 direct toxicity. Some observed disorientation was attributed to tur- 

 bidity. Samples with solids concentrations up to 5 percent did not 

 produce significant mortality after the 48-hour period of the bio-assay, 

 or during the subsequent day of observation. 



Based on the results of the chemical and fish bio-assays, the study 

 concluded that bottom sediments of Olympia Harbor appear to be moderate 

 to low in toxicity, and much less than those of Bellingham Harbor. 



8. Great Lakes 



Studies of the effects of dredging on water quality in the Great 

 Lakes concluded that lack of uniform procedures for sampling and 

 analysis, make such investigations difficult (U. S. Army Engineer 

 District, Buffalo, 1969). The problem is further compounded by the 

 variation in the degree of pollution of sediments at different harbors. 



The studies concluded that dredging has little influence on water 

 quality, especially where the water is already polluted. At harbors 

 such as Rouge River and in Great Sodus Bay, some temporary adverse effects 

 were observed. At other harbors, such as Buffalo and Cleveland, dredging 

 appeared to have a beneficial effect because of the removal of polluted 

 materials. The studies, however, were inconclusive as to the fate and 

 effects of dredge spoils following disposal in the Lake. 



The effects of spoil disposal on the water quality and on the flora 

 and fauna were equally in doubt. Bio-assay investigations with dredge 

 spoil by the University of Wisconsin, suggested a relationship between 

 the chemical composition of these sediments and their toxicity or algal- 

 growth promoting potentials. Based on these bio-assays, the reviewing 

 Board of Consultants concluded that the long-term impact of open-water 

 disposal of dredge spoils on eutrophication is not known, because water 

 quality criteria are not well established. The Board acknowledged that 

 in-lake disposal of heavily polluted dredge spoils is undesirable because 

 of its long-term adverse effects on the marine environment and ecology 

 of the Great Lakes. 



9. Other Countries 



a. Scotland and England . Sewage sludge from the city of Glasgow and 

 adjoining areas has been dumped in the Firth of Clyde for years at an 

 average rate of 1 million tons per year. 



Preliminary investigations (Mackay and Topping, 1970) covered the 

 composition of the sludge, the hydrography of the dumping area, and 



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