Prescott has been monitoring the watershed’s water quality and ecological health for the past seven years. He said Little Narragansett Bay is stressed by elevated bacteria levels, high nutrient loads, large, thick mats of macro-algae, poor flushing in shallow coves, and decreased dissolved oxygen levels. These stressors are threatening water quality, marine and coastal ecosystem health, and the region's recreational value, he noted.
Elevated bacteria readings have been documented in both wet and dry weather conditions in the upper estuary. Near the downtowns of Westerly and Pawcatuck, Conn., a number of outfall pipes directly discharge into the Pawcatuck River.
Save The Bay touted the recent invitation-only outing as a call to action, to urge local communities — and not just Westerly and Stonington, Conn. — and their residents to help mitigate pollution impacts. The Providence-based nonprofit also would like agencies and officials in both states to better enforce the environmental regulations that protect this shared natural resource.
The environmental group is pushing watershed municipalities along the coast and upstream to develop plans to better manage stormwater runoff, ensure septic systems are working properly and to closely monitor the watershed.
Much like the problems facing areas of Narragansett Bay and Long Island Sound, contaminated stormwater and combined sewer overflow washing into Little Narragansett Bay are causing parts of the bay to degrade. This runoff and overflow carries oil, gasoline and grease, lawn fertilizer, pet waste and bacteria. This pollution has closed part of Little Narragansett Bay to shellfishing since 1991.
Since 2007, when Save The Bay opened its South Coast Center in Westerly, it has been testing, in cooperation with the University of Rhode Island’s Watershed Watch program, in six locations in Little Narragansett Bay/Pawcatuck River, documenting water temperature, clarity, salinity, and nutrient, dissolved oxygen and pH levels.
While continued monitoring shows water quality is impaired and problems persist, scientists need more data to fully understand the bay and its watershed, Stone said.
Much of the area in the watershed is built up and covered with impervious surfaces, which rushes stormwater pollution into Little Narragansett Bay. In fact, a third of Rhode Island’s runoff drains into the Pawcatuck River watershed, according to Prescott.
Thanks to large amounts of nitrogen, much of it from lawn fertilizers, contained in this runoff, thick mats of macroalgae — called “black ooze” or “black mayonnaise,” depending on whom you are speaking with — cover much of the bottom of Little Narragansett Bay between Watch Hill and Sandy Point.
This patchwork blanket of algae, which gives off a rotten-egg smell when a piece is pulled into a boat or some of it washes into shore, creates low-oxygen zones that suffocate eelgrass and iconic New England marine life such as oysters and scallops. In some places, this decaying organic matter is several feet thick and spreading, according to Prescott.
The University of Connecticut and the University of Rhode Island are both studying this algae formation, which shows no signs of disappearing.
“It’s not quite a dead zone, but it isn’t really what it should be,” Prescott said. “We don’t want to see Little Narragansett Bay any more impaired than it is now.”