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<br />ABSTRACT <br /> <br />The pollutional characteristics of stormwater runoff were <br /> <br /> <br />evaluated by sampling stormsewer discharges at appropriate <br /> <br /> <br />intervals throughout each runoff period for several storms <br /> <br /> <br />at three locations. The study was made in Boulder, Colorado <br /> <br /> <br />and the emphasis was placed on the chara<i:teristics of snowmelt <br /> <br /> <br />runoff. The runoff from three types of land use areas was <br /> <br /> <br />stud,ied. The sampling locations included the stormsewer outfall <br /> <br /> <br />on Boulder Creek for a urbanized residential are,a with a <br /> <br /> <br />population density of twenty-five persons per acre (62 persons <br /> <br /> <br />per hectare); the outfall of the stormsewer serving a suburban <br /> <br /> <br />area with a density of twelve persons per acre (30 persons <br /> <br /> <br />per hectare); and the runoff from an uninhabited, unsewered <br /> <br /> <br />mountain watershed. <br /> <br /> <br />The results of the study showed that snowmelt pollution <br /> <br /> <br />is re~eased more slowly than rain runoff to a receiving stream <br /> <br /> <br />and therefore the maximum concentrations were lower than those <br /> <br /> <br />for rainfall. The total mass loadings were slightly lower for <br /> <br /> <br />snowmelt compared to rain runoff on the same area for the major <br /> <br /> <br />pollutants, COD, total and suspended solids. The mass loading <br /> <br /> <br />were much lower in snowmelt for the nutrients, nitrogen and <br /> <br /> <br />phosphorous. <br /> <br /> <br />Preliminary treatment evaluations of stormwater runoff <br /> <br /> <br />were made using the process of plain sedimentation, coagulation- <br /> <br /> <br />sedimentation using lime, alum, and ferric chloride and by <br /> <br /> <br />sand filtration. Due to the colloidal nature of the organic <br /> <br />. <br /> <br />" <br /> <br />. <br /> <br />. <br /> <br />ii <br /> <br />~ <br />