Trophic State and Eutrophication - Freshwater Ecology: Concepts and Environmental Applications - page 356

environments caused by nutrients delivered by streams (Turner and Rabal-
ais, 1994; Conley, 2000).
Historically, one of the worst problems with sewage input to streams
and rivers is the loss of O 2 and the introduction of pathogenic bacteria
(Fig. 17.13A). Modern sewage treatment does not lower total nutrient
FIGURE 17.13 Chemical and biological parameters as a function of distance downstream
from untreated sewage effluent (A, redrawn from Hynes, 1960) and from a modern sewage
treatment plant (B).