Technical Bulletin No. 0368: Effects of Biologically Stabilized Bleached Kraft Mill Effluent on Cold Water Stream Productivity as Determined in Experimental Streams – First Progres

During the period covered by the material reported in this technical bulletin, biologically treated bleached kraft mill effluent was introduced in sufficient quantity to add an increment of 0.5 ppm Five-Day Biochemical Oxygen Demand to the stream; this represented an incremental addition of 0.8 ppm non-settleable biological solids, and about 50 color units. Macroinvertebrate density and biomass was observed to be significantly greater, and rainbow trout production was 20 percent greater in the streams receiving effluent. In an array of early life stage egg-larval bioassays, no effect was noted until effluent concentrations exceeded 10 percent; the concentration of effluent in the test streams after the first year of study was doubled. It ultimately accounted for an incremental BOD addition by the effluent of about 1 ppm.