WESTERLY — As people flocked to the water during the sweltering month of July, some of them were swimming in contaminated water. Test results of the Little Narragansett Bay watershed from the University of Rhode Island’s Watershed Watch water-quality monitoring program showed that in several locations, it was unsafe to swim.
Many of the 27 testing sites in southwestern Rhode Island and eastern Connecticut showed levels of fecal coliform and enterococci bacteria that far exceeded levels considered safe for swimming. Both bacteria indicate the presence of human sewage and associated pathogens, which can cause diseases.
Samples collected by volunteer monitors and tested at the Rhode Island Department of Health laboratory in May, June and July show increasing bacteria levels, with the highest recorded in July.
Watershed Watch cautioned people not to swim after a heavy rainstorm, because runoff entering the Pawcatuck River and Little Narragansett Bay carries numerous contaminants, including bacteria.
“Any result above the state standard is considered unsafe, and swimmers should refrain from swimming until results return to acceptable levels, or at least for several days after heavy rain,” the group's website states.
Save The Bay South County Coast Keeper David Prescott has been monitoring water quality in the Little Narragansett Bay watershed since 2007 and working with Watershed Watch since 2008.
“We don’t get these small rainstorms anymore,” he said. “We get these intense, massive downpours that drop inches of rain, and that has big impact in terms of elevating the bacteria level.”
Under the Watershed Watch program, twice a month, water is tested for dissolved oxygen levels, temperature, pH, chlorophyl, salinity and turbidity, and once a month, bacteria and nutrient levels are measured. Prescott said his bacteria testing day just happened to come after a large rainstorm, so levels were very high.
“We actually tested the day after the last storm, I think it was a couple of weeks ago, when we got that 3½-inch-rainfall storm,” he said. “Our numbers were super high, not just in the river but all the way out in the bay. The concern for that has everything to do with human health. Bacteria can make us very sick, and when we have rainstorms that drop that much rain and bacterial levels that are anywhere from 10 times, to, I think in one case, 60 times the EPA’s limit for enterococci, which is the swimming standard, that makes us very, very concerned.”
Fecal coliform and enterococci are the focus of bacteria tests because their presence indicates contamination by pathogens.
The DEM states, "fecal coliform is used to determine risk for shellfish consumption, while enterococci is used to determine risk associated with primary and secondary contact recreation activities in the state’s fresh and salt waters. Enterococci recently replaced fecal coliform as the indicator bacteria for contact recreation uses in the Rhode Island water-quality standards.”
The tests measure fecal coliform and enterococci levels per 100 milliliters of water. The Rhode Island Department of Health enterococci swimming standard is 60 per 100 mL for beaches. The state’s fecal coliform limit is 14 per 100 mL.
Connecticut and Rhode Island measure test results against a “geometric mean,” or average standard, for each test site. In July, the highest fecal coliform levels, 6,015 bacteria per 100 mL, were found where Mastuxet Brook joins the Pawcatuck River. The geometric mean, or standard, is 354 per 100 mL. The mouth of the Pawcatuck showed high levels of fecal coliform: 4,034 per 100 mL, far exceeding the standard of 34.
Enterococci at the mouth of the Pawcatuck were also far above the standard level of 168, with 4,352 per 100 mL.
High levels of fecal coliform were evident at Wequetequock Cove Inlet, with 2,005 per mL, far above the average standard of 169.
For people who have already been swimming, the test results obviously come too late. The challenge, Prescott said, is persuading people who are used to swimming in certain areas that it isn’t safe to do so. Bacteria levels in the Pawcatuck River, for example, regularly exceed the total maximum daily loads set by Connecticut and Rhode Island.
“I’ve gotten a lot of calls asking how safe the water, especially the river, is,” he said. “Based upon the TMDL for DEM and Connecticut, the river is not suitable for primary contact, meaning swimming.”
With the summer’s numerous beach closures, Prescott said public awareness of water quality is high but people still resist advisories to stay out of the water.
“People come up to us when we’re out there testing saying ‘how healthy is the river?’ And I basically say to them ‘The Pawcatuck River is not suitable for swimming,’ and usually I get a little bit of pushback, ‘Oh I’ve been swimming here for decades,’” he said. “So basically what I say is, based upon the current conditions, it is not suitable for swimming whether it’s dry weather or wet weather. And DEM would echo that. Basically they would say the same thing. This area is not suitable for swimming.”