The purpose of the RiverWatch Water Quality surveys is to determine whether or not sites along the North and South Rivers have exceeded colony concentration numbers compared to Massachusetts water quality standards for swimming and shellfishing for bacteria. Enterococcus colonies were measured across all ten sites, while fecal coliform was analyzed only in sites noted as areas where shellfish were being harvested. According to Massachusetts’ swimming standards, enterococcus levels may not exceed 104 cfu per 100mL of water sampled and additionally, fecal coliform concentrations may not exceed 14 cfu per 100mL.
After analyzing the collected water samples, for the week of June 13, it was found that water at Washington St. Bridge and Keville Footbridge exceed Massachusetts’ swimming standard for enterococcus. The concentration of enterococcus is much higher than in recent years, however it is likely that these levels are due to rainfall in the area. Over the course of 72 hours prior to June 12, when the samples were collected there was approximately 0.80 in of rainfall, increasing the amount of stormwater present.
Furthermore, concentrations of fecal coliform exceed the shellfish standard at Driftway Park, North River Marine, and Julian Street Bridge. These levels are in fact lower than the past 2 years, meaning that improvements to the area have been beneficial. However, some caution must still be taken as many designated shellfish areas still exceed the standard for consumption. (The shellfish beds are closed seasonally from May 31 to November 1 and these water quality data comparisons to shellfish standards are for informational purposes only.)