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<br />treated wastewater with a concentration of 10 mg/~. <br /> <br /> <br />It can be concluded from these data that the pOllutional <br /> <br /> <br />contribution of the discharges from separate storm sewers may <br /> <br /> <br />have a significant impact on a receiving stream since the con- <br /> <br /> <br />centrations of chemical oxygen demand and suspended solids are <br /> <br /> <br />generally higher than would be permitted for sewage treatment <br /> <br /> <br />plant effluents. It is also apparent that a high degree of <br /> <br /> <br />vacriation in pollutional quality has resulted from different <br /> <br /> <br />cities and that generalizing on the pollutional strength of <br /> <br /> <br />stormwaters can only be done in broad terms. <br /> <br /> <br />The major reason for the highly variable pollutional strengths <br /> <br /> <br />of stormwaters is the large number of factors relating to the <br /> <br /> <br />storms producing the runoff and to the character of the catch- <br /> <br /> <br />ment areas. Some of the relationships associated with these <br /> <br /> <br />factors have been investigated and reported in the literature. <br /> <br />B. Rainfall and Snowmelt <br /> <br /> <br />Most of the previous work on stormwater quality has related <br /> <br /> <br />to rainfall events. A few articles have been published on the <br /> <br /> <br />effects of snowmelt runoff and the impact of deicing chemicals. <br /> <br /> <br />A study in Des Moines, Iowa involved storm sewer discharge <br /> <br /> <br />sampling for a twelve month period (Lager and Smith, 1974). The <br /> <br /> <br />study involved both combined sewer overflows and separate storm <br /> <br /> <br />sewer discharges. The data for snow events was separated in the <br /> <br /> <br />data and compared with rain events. The results are shown in <br /> <br /> <br />the following table. <br /> <br />12 <br /> <br />. <br />