Abstract
The Buzzards Bay watershed includes nine coastal communities in southeastern Massachusetts and Cape Cod with swimming beaches and extensive shellfish resources. This area has been the focus of environmental advocacy for the past few decades. Using modern stormwater management equipment, this study focused on detecting pollutants entering stormwater conveyance systems in Buzzards Bay, specifically looking at the watershed of Tub Mill Brook in the Town of Mattapoisett. In attempting to create rules for prioritizing stormwater investigations, four years of stormwater discharge water quality data were evaluated. Models were created in the attempt to quantify relationships between how an area of land is used (i.e., forest, commercial, residential, recreational, saltwater, freshwater, etc.) and the concentration or total load of contaminants found in stormwater conveyance systems. Weak correlations between pollutant discharge and land use were found, but the results were not sufficiently predictive of high contaminant concentrations entering stormwater systems. In the case study, a systematic monitoring approach was used to identify potential illicit connections and analyze contaminants entering Tub Mill Brook. An inventory of existing stormwater infrastructure was performed, which included inspection and GPS tagging of structures, with most of the stormwater system in good condition. The collected data was used to update an online GIS database for Buzzards Bay Watershed. After five months of sampling water from outfall pipes along the brook and testing them for contaminants, Park Street in the Town of Mattapoisett was identified as a likely area where a nitrate source was polluting the brook. Surfactants and fecal bacteria were also high within the watershed especially along Route 6, one of the most trafficked roads in the area. Recommendations for the Town of Mattapoisett are that they continue monitoring the outfall pipes under dry and wet weather conditions, put a plan into place to inspect certain structures that require more specialized equipment, and use the findings of this study to better focus resources managing stormwater discharges to Tub Mill Brook.