Managing Sewage Overflows Can Help Abate Climate Change

Sep 20, 2019

As global climate strikes take place across the region today, another focus of climate change is an unaccounted-for source of greenhouse gas emissions. Hudson River sewage overflows are the culprit, and a new study suggests that stopping water pollution is an untapped strategy to mitigate climate change.

Here’s the problem:

“The Hudson River becomes a source of a potent greenhouse gas — methane — when we release untreated sewage to it,” Shapley says.

Dan Shapley is Water Quality Program Director with Riverkeeper. The Queens College study uses data gathered from Riverkeeper’s patrol boat. The study found the highest concentrations of methane, a greenhouse gas more potent than carbon dioxide, were released from the Hudson River Estuary in the Capital District and in New York City.

“Well, in the Capital District, as we know, there’s six communities that all have combined sewers, so it’s kind of the highest concentration of communities that still are reliant on pipes that carry both the sewage from our toilets and the storm water from our streets in the same pipes, and so they’re designed to overflow when it rains,” says Shapley. “Now, of course, Albany, Troy and the other communities in the region are working on a long-term plan to reduce those overflows. And what this study points out is just the urgency of that. that it’s not only the water quality issue we knew it to be,  it’s not only the local environmental issue we knew it to be, but it’s also really global issue of climate change and that we’re causing more emissions of greenhouse gases by allowing those releases of sewage to the water.”

The study also finds that the Hudson River ranks high among world estuaries for methane emissions, based on the available data. Dr. Brian Brigham is a researcher at Queens College and an author of the study.

“What we found was that really high greenhouse gas production is very limited in scope and it’s very difficult to measure, but there’s a strong correlation between these moments and wastewater delivery areas,” Brigham says. “So I think what we’ve learned was that the Hudson River and other urban estuaries have a great potential to produce greenhouse gases due to anthropogenic influences, and we’re not really measuring it right now. So I just think the study shows that more measurements are needed that focus on those particular areas in both space and time in particular.”

He and Shapley say the study has the potential to alter the way governments prioritize strategies to manage sewage and reduce greenhouse gas emissions, making water quality improvements a tool to fight the climate crisis. Brigham says addressing the issue needs to go beyond protecting human health.

“But in New York City, they’re thinking about just chlorinating the wastewater effluent more heavily to reduce the risk of contamination and risk to human health,” Brigham says. “But that doesn’t really consider the impact that wastewater treatment has on these greenhouse gas productions.”

Shapley calls the study groundbreaking, and the estimates within, likely underestimates.

“And so I think the initial estimates that are in this study, I think, we’re going to see tick up up up and up in terms of our understanding of the impact of this type of pollution not just on the water, but on greenhouse gas emissions,” says Shapley.

He says the study’s estimates are equal to the emissions of at least 41,000 cars. Shapley urges New York state, New York City and all river cities that are releasing raw sewage when it rains to move faster to eliminate overflows.

And in looking at climate change, Shapley hopes this source of greenhouse gas emissions is considered as part of the bigger picture, and is added as a target of climate action. Meantime, Brigham is wrapping up a related study.

“We have a third well, for my PhD, but we have a follow-up paper that’s coming out that examines the effluent combined sewer overflows much more closely,” says Brigham. “And there’s a lot of, we collected a lot of evidence that demonstrates that, yes, these CSOs are both sources of greenhouse gases and they feed organisms into the environment that can produce these greenhouse gases and they source a lot of carbon and nitrogen into the environment, too, to enhance production.”

Brigham hopes to publish the study by the end of the year.