The bacteriological effect of combined sewer overflows on the Detroit river.

Many of the older cities in the United States have combined sewers in which stormwater and sanitary wastewater enter the same system. In recent years, more and more concern has been voiced about the pollutional effects of overflows from these com bined sewer systems. This paper gives the results of a special study conducted by the Detroit River-Lake Erie Project of the Federal Water Pollution Con trol Administration concerning the bacteriological effects of overflows from combined sewers in the Detroit Metropolitan Area. The receiving wa ter for the sewer discharges was the Detroit River. Although combined sewer overflows are recognized as a serious source of pollution by several authors (1) (2) (3) (4), very few examples of the seriousness of this problem are in the literature. One author (5) (6), in fact, suggests that the pollutional load from the discharge of a separate storm sewer system may be compar able to that released from a combined sewer system. Figures obtained from Jamaica Bay, New York, after a mod erate rain show the coliform MPN density to be as high as 79,110 or ganisms/100 ml (7). A later paper by