IMPACT OF URBANIZATION ON WATER QUALITY IN URBAN STREAMS

Development dramatically decreases water quality in urban streams. Additional sources of contaminates exist such as stormwater runoff and combined sewer systems that deliver elevated contaminant loads, especially during high discharge events. A wide range of contaminants have been detected including nitrogen, phosphorous, trace metals, coliforms and anthropogenic organics. However, the chemical composition of streams varies within an event, representing contributions from multiple sources. In addition to excess loading, development alters natural biogeochemical cycling of nutrients and carbon, impacting ecosystems as well as contaminant cycling. Management of contaminant loading under continued development pressure continues to challenge municipalities. To assess potential changes in loading and chemical cycling, we have collected stream water samples in the Park River sewershed (Hartford, CT) during multiple events in August 2010, February 2011, and May 2011. Trace metal, nitrogen speciation, TSS and DOC content and quality were evaluated for each sample. All samples contained low DOC with the majority of the flux occurring in the particulate phase. However, dissolved transport was a significant factor during the February event. TN flux was consistent between storms, reflecting the influence of flow on flux. However, during the February event, flux was higher per unit discharge for the urban sites, potentially reflecting the influence of CSOs. NOx represented the dominant N species during August and February. Organic N was the largest fraction during the May event.