The RiverWatch Water Quality surveys determine whether or not sites along the North and South Rivers have exceeded colony concentration numbers per Massachusetts’ swimming and shellfishing standards. Enterococcus colonies were collected at all ten sites along the North and South Rivers, while fecal coliform samples were collected in shellfish growing areas (none of which are open at the moment for harvest). According to Massachusetts’ swimming standards, enterococcus levels may not exceed 104 cfu per 100mL of water sampled. The Mass. Division of Marine Fisheries shellfishing standard is 14 cfu per 100mL of fecal coliform.
For the week of July 10th, water at Washington St. Bridge, Cornhill Lane, and Keville Footbridge exceeded the Massachusetts’ swimming standard for enterococcus. Water at Washington St. Bridge and Keville Footbridge has had a consistently high concentration of enterococcus in the past three rounds of sampling, but Cornhill lane has increased from 10 cfu per 100mL to 275 cfu, now exceeding the standard. The cfu values of all three sites has continually increased over the past three rounds of sampling.
Shellfish beds are closed from May 31 until November 1 so the information presented in this section is purely for informational purposes. Concentrations of fecal coliform exceeded the shellfish standard at all five sites: Driftway Park, North River Marine, Damon’s Point, North River Mouth, 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 now all designated shellfish areas still exceed the standard for consumption per Massachusetts regulation.
In this round of sampling both enterococcus and fecal coliform concentrations were consistently high at the same sites, some new sites, and generally increased compared to the last round. Even though there was not any rainfall in the past 48 hours prior to sampling, there has been frequent and high amounts of rainfall in the weeks prior to this week’s sampling and may be the cause, along with warmer temperatures, for the higher concentrations.