Report: Key pollutants down at Pawtuxet River testing site

By DANIEL A. KITTREDGE
Posted 4/23/20

The waters of the Pawtuxet River, as measured from a testing site near Rhodes on the Pawtuxet, have seen a significant drop in some key pollutants in recent years, according to the program director of the University of Rhode Island's

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Report: Key pollutants down at Pawtuxet River testing site

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The waters of the Pawtuxet River, as measured from a testing site near Rhodes on the Pawtuxet, have seen a significant drop in some key pollutants in recent years, according to the program director of the University of Rhode Island’s Watershed Watch.

“Overall, for a highly urbanized river system, the Pawtuxet River near Rhodes is in pretty good condition, and seems to be responding well to removal of the dam [in Pawtuxet Village in 2011],” Elizabeth Herron wrote in an update recently published in the Friends of the Pawtuxet newsletter. “As efforts in the watershed to further reduce nutrient loading continue, the river should show more signs of improvement.”

According to Herron’s report, there has been a “significant and important reduction” in total phosphorus, or TP, at the testing site. Herron notes that high levels of phosphorus – the “driving nutrient in freshwater systems” – can result in “harmful levels of algae or plant growth.”

TP levels at the Rhodes testing site peaked at approximately 122 parts per billion, or ppb, in 2013 – a figure that exceeds the 100 ppb threshold for what is considered elevated. The years since have brought a “steady decline,” according to Herron, culminating in an average TP level of 26 ppb in 2019.

Herron states that the 2011 removal of a dam in Pawtuxet Village may have contributed to the decline in phosphorus levels in the river, given that “water and other organic materials aren’t getting trapped and concentrating behind the dam anymore.”

Another key development, according to Herron’s report, is that total nitrogen, or TN, levels from the test site have held steady or declined over the same time period.

She suggests efforts to reduce and treat stormwater within the river’s watershed – and specifically at Roger Williams Park – have likely played an important part in keeping nitrogen levels in check. That, in turn, has benefited Narragansett Bay.

“Total nitrogen is considered the limiting nutrient in marine systems, and with Pawtuxet Cove just downstream the TN concentration has an important impact on the bay,” her report reads. “While the TN concentrations remain in the elevated nutrient range indicative of the urban areas that drain into the Pawtuxet River, they are declining slightly.”

Bacteria levels have also declined in samples from the Rhodes site, according to Herron. In 2017, four of six sampling events exceeded the “swimming contact standard,” according to report. That fell to three of five in 2018 and just one of six in 2019.

“Those low values in 2019 were really interesting because that was a wet summer, when we would have expected higher bacteria levels,” Herron’s report states. “The stormwater control systems that reduce nutrients also reduce bacteria, so we may be seeing improvements in bacteria from those efforts, too.”

Herron’s report notes that bacteria levels in recent years “may not support swimming in the river yet, but they do suggest that kayaking or canoeing the river is OK” with the use of appropriate safety procedures and equipment.

Citywide Councilman Steve Stycos, one of the founders of the group Friends of the Pawtuxet, called the figures outlined in Herron’s report “great” and “so encouraging.” In a tangible sign of the improvement, he said in recent years he has noticed more people fishing on the lower Pawtuxet River.

He credited John Dineen, a member of the Friends group who conducted the Rhodes on the Pawtuxet site sampling for a number of years, and others who have participated in clean-ups and other activities to help improve the river.

“I hope that in some small way we contributed to that,” he said.

Stycos said he hopes additional work can be done to address runoff within the river’s watershed, including at Meshanticut Lake. He said he and Wenley Ferguson, director of habitat restoration at Save The Bay, have had initial talks with the state Department of Environmental Management and the city’s Parks and Recreation Department about additional runoff mitigation for the lake.

For more information on the URI Watershed Watch program, visit web.uri.edu/watershedwatch.

Comments

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  • thepilgrim

    As more leftist politicians destroy business the air and water is getting cleaner. When the economy totally fails then the waters will be as pristine as they were when the Pilgrims first came. We can all drink pure water when we’re bankrupted.

    Thursday, April 23, 2020 Report this

  • Justanidiot

    Robert, once we eliminate people, the world will be so much better. just think of north america before anyone was here. corvid is just a government plan to eliminate everyone.

    Thursday, April 23, 2020 Report this

  • thepilgrim

    Just anidiot, Totally agree. And the final nail will be Bill Gates’ mandatory vaccine.

    Thursday, April 23, 2020 Report this