The Bacteriological Aspects of Stormwater Pollution
Journal Water Pollution Control Federation , 40 , 1968

Geldrich, E.E., Best, L.C., Kenner, B.A., Van Donsel, D.J.

There has been a growing concern in recent years with the pollution con tributed to streams from stormwater drainage. Earlier bacteriological an alysis of separate and combined sewer systems measured only the total coli form population present in this pol lutional source (1) (2) (3) (4). Re cent studies on the origins of fecal coliforms and fecal streptococci have generated renewed interest in these groups as better indicators of pollu tion by warm-blooded animals than the total coliform group traditionally used in stream pollution investigations (5). Using additional bacteriological pro cedures, Weibel et al. (6) determined that 90 percent of all stormwater sam ples from a separately sewered urban area had counts of total coliform, fecal coliforms, and fecal streptococci exceeding 2,900, 500, and 4,900/100 ml, respectively. Burm and Vaughn (7), in a bacteriological comparison study of combined and separate sewer discharges also used these three bac teriological parameters. They found the total coliform densities in the sep arate storm sewers to be approxi mately one-tenth of those in combined sewers where median monthly values were as high as 37,000,000 coliform organisms per 100 ml. Fecal coli form densities were approximately 20 percent of the total coliform in com bined sewage. Analysis of their data indicated the fecal coliform content of separate systems to be 7.6 percent of the total coliform population. They also reported that discharges from the combined sewer system have fecal streptococcus densities about twice as great as those from the separate storm system (508,000 vs. 208,000/100 ml). Although there now is available ex cellent quantitative data to demon strate the magnitude of stormwater bacterial pollution densities, the sur vival and persistence of these orga nisms in stormwater as related to sea sonal temperatures and nutrients avail able, the probable sources of the fecal and nonfecal pollution, and the fur ther evaluation of the potential health hazard by quantitative pathogen de tection have not been reported. These areas were selected for the develop ment of this research project.