DETERMINING EFFECTS OF PHYSICAL CHARACTERISTICS OF STORM SEWER SHEDS ON THE WATER QUALITY OF AN URBAN STREAM

Increasing urbanization has consequences for surface water quality. The leading contributor of contaminants to urban streams is stormwater. However, interactions between stormwater and urban landscapes are not fully understood. Studies of urban environments as a whole have shown several trends in regard to water quality. Higher percentages of impervious surface cover are associated with increased runoff and degradation of water quality. Detention ponds, originally designed to reduce flow, can provide some treatment. Contact with cement piping can contribute ions and increase pH. We hypothesized that individual storm sewer systems would show significant differences in water quality based on their physical attributes. We investigated how area, pipe density, pipe miles, percent impervious surface cover, the presence of ponds, presence of sumps pumps and zoning affect the water quality of stormwater leaving storm sewer systems. Dependent variables were selected based on their indication of water quality, including many standard water quality parameters. Stormwater grab samples were taken from seventeen stormwater sewer pipe outlets. Onsite analysis was done with a YSI Pro Plus, laboratory analyses included oven drying sediment, ion chromatograph, flame adsorption and flow injection. The presence of a pond within a storm sewer system significantly increased water quality. Storm sewer systems with more miles of piping show a significant positive correlation with water quality. Storm sewer systems with sump pumps have significantly better water quality. Overall, there are some physical characteristics of storm sewer systems that were associated with cleaner water being discharged during storm events.