Scientist clarifies rumors about amount of pollution in Narragansett Bay
Last month an advocacy group called Environment Rhode Island released a fact sheet titled “Ten Scariest Facts about Narragansett Bay.” In the report it said a “frightening mix of pollutants including nitrogen, phosphorous and heavy metals have made Narragansett Bay a ghost of its former self.”
The report added that stormwater run-off and inadequate sewage treatment were turning the bay into a “potion of pollution.”
Since then, a local scientist has come forth to clarify, and in some cases correct, some of the myths about the bay. He said that great strides are being made to improve the body of water.
Dr. Christopher Deacutis is the chief scientist at the Narragansett Bay Estuary Program. The organization is part of the National Estuary Program, a national network of 28 programs working for collaborative solutions for estuaries designated by Congress as of critical importance. The National Estuary Programs were created in 1987 under the Clean Water Act. They are charged with protecting and restoring U.S. estuaries by interfacing with state and federal agencies, nongovernmental organizations, and local communities in planning and management decisions and actions.
Among the points raised in the Environment Rhode Island publication was that as a result of the combined sewer and storm drain system in Providence, heavy rains had overwhelmed the state’s wastewater treatment plants, resulting in the discharge of raw sewage into the bay. Deacutis points out that much of the information cited in the publication is taken from a report published by the Narragansett Bay National Estuary Research Reserve, a federally funded organization that is run by the state of Rhode Island
The report was published in 2005. Since that time, according to Deacutis, the combined sewer overflow system came online in 2008, and that the condition of the bay has improved significantly in that regard as a result.
The Environment Rhode Island paper also claimed that National Oceanographic and Atmospheric Administration had cited Narragansett Bay as one of the 20 most polluted bays in the country due to the presence of heavy metal in the water. Deacutis contends that while that information was accurate at one time, it is no longer the case.
“That was probably the thing that bothered us the most,” Deacutis said. “That comes from a NOAA report from back in 1989.”
“Since that time we have gone through some major changes in the bay,” Deacutis continued. “This is sort of ignoring quite a bit of money that’s been spent, and quite a bit of effort from a lot of people to try and get the bay cleaner.”
Deacutis acknowledges that there was a massive die-off of fish and clams in the bay as a result of excessive nutrient pollution. “Dealing with nutrients is a fairly new thing,” Deacutis said. “Nutrients have not been dealt with by the rules in most sewage treatment plants until recently. They have to go through a third level of treatment in order to remove the nutrient.”
The scientist expects the low oxygen condition (caused by excessive nutrients) in the bay to improve as the third level of treatment comes online at the treatment plants. It has been five years since the first plant began operating under the new rules, but there are still more plants that have to adopt the new technology. As an example, the major sewage treatment plant in Providence won’t activate the third stage until 2013. So while the excessive nutrient problem remains, major steps are being taken to remediate it.
Even if no new nutrients enter the bay, it will take some time to dissipate the low oxygen problem. Just how long, no one can say. “We don’t know, and it’s probably not going to get completely dissipated because part of this, myself and a number of other scientists believe, is linked to issues of global climate change,” Deacutis said.
Scientists have noted that summer rains tend to make the oxygen situation in the bay much worse. While there have always been summer rains, Deacutis and his colleagues believe that climate change has increased the intensity of the storms. “If we have heavy rains, not necessarily in the spring or fall, but in the warm summer months, that summer turns into a very nasty summer for low oxygen,” he said.
Scientifically this occurs because a saltwater estuary, like the bay, has cooler saltier water on the bottom, and fresher, slightly warmer water, on the top. When the various levels separate, it is called density stratification. As a result of the stratification, the oxygen from the atmosphere goes into the top level, but never reaches the bottom level.
As a result of summer rains, the rivers flow heavily into the bay and the stratification takes place. Oxygen at the bottom then begins to deplete. Algae blooms die and float to the bottom where bacteria use oxygen to break the plants down. Until the water gets mixed again, the oxygen level on the bottom remains low. One solution to this problem is to decrease the amount of algae by robbing them of the nutrients that they need to survive, thus diminishing the amount of oxygen being used by bacteria.
No one, however, can stop the rain. “There is going to still be a certain amount of risk of low oxygen, but we’re expecting it will not be as bad as it has been in the last 10 years,” Deacutis said.
Another issue address by Environment Rhode Island was the water quality at Scarborough Beach in Narragansett as reported by the National Resources Defense Council. Deacutis acknowledges this problem and cites the presence of a big storm drain near the beach as the culprit. While the nutrient problem is being widely addressed, the storm water situation has yet to be resolved. “Storm water always carries bacteria off land,” Deacutis said. “So if you have storm water running right to the beach, especially a big drain, that’s going to affect the quality of the water at the beach.” He said that possible solutions for this problem are currently being studied.
Deacutis said that claims that 420 metric tons of oil are being discharged into the bay on an annual basis are based on an old report by URI professor Dr. James Quinn. Since that time, the amount of oil entering the bay has decreased as a result of modern automobiles spilling less oil on the roads, and oil resulting from automobile oil changes is now, for the most part, being recycled instead of going into the sewer system.
A recent URI study showed the presence of emerging pollutants at 27 locations throughout Narragansett Bay, including Potter Cove in Jamestown. Deacutis said that the degree of pollution is not equal throughout the bay. “There is a very clear gradient of pollutants coming down the bay,” Deacutis said. “The highest level of pollutants are up by Providence and maybe western Greenwich Bay, and they get lower and lower as you come down the bay. By the time you get to Jamestown they’re pretty low.”
According to Deacutis, the issue of emerging contaminants and their possible impact on the bay is something that bears close monitoring.