A baseline for biological and chemical water quality conditions was established for a section of the Welland River which daily receives large quantities of nitrogenous and carbonaceous inorganic compounds from Cyanamid of Canada Limited.

Specific conductivity transects across the river at various locations indicated that the effluents discharged clung to the north shore of the River. In addition, simultaneous continuous conductivity measurements from above and below the plant were made during five one-week long periods and the results temperature corrected. At the upstream site conductivity never exceeded 400 limhos/cm while below the plant it averaged 950 umhos/cm with sporadic peaks exceeding 1 0,000 umhos/cm.

Epiphytic diatoms scraped from typha stalks growing in the water at sites above the plant were dominated by Nitzschia dissipata, while the pollution tolerant diatom, Nitzschia palea, dominated at the majority of the downstream sites. In addition, blue green algae replaced filamentous green algae below the plant.

Higher aquatic plants reflected a very distinctive zonation pattern. No higher aquatics were found growing in the water in the impact zones immediately below the effluent outfalls. The first macrophytes to appear downstream of these sites were cattails, while further downstream the arrowheads (sagittaria) and later the submersed macrophytes, such as Elodea and Myriophyllum appeared.

No resident fish population occurred along the north shore downstream of the plant. Shiners and other small transient fish species which were observed entering the effluent plume near Thompson's Creek during periods of shock loading went "belly-up" within one minute indicating the extreme toxicity of these waters.

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