After historic sewage spill, George Mason researchers monitor for long-term impacts with support from NSF grant

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On January 19, 2026, a sewer line in Montgomery County, Maryland, collapsed. More than 240 million gallons of wastewater overflowed into the Potomac River. It was one of the largest sewage spills in United States history, right in George Mason University's backyard.

While a temporary fix to the pipe was completed in March and DC Water continues to actively remediate the area, questions of long-term impact to this distinctive tidal freshwater estuary system linger. The team at George Mason's Potomac Environmental Research and Education Center (PEREC) hopes to find answers.

This summer, seven George Mason researchers received a RAPID grant of $299,886 from the National Science Foundation (NSF) to investigate how the sewage spill may have impacted water quality, aquatic life, and the overall health of the estuary. Led by co-PIs Amy Fowler, associate professor and interim director of PEREC, and Jennifer Salerno, associate professor of environmental science and policy and faculty fellow at PEREC, the grant team includes environmental science and policy faculty Thomas Reid Nelson, Cindy Smith, and Rosalina Christova, as well as Brittany Hupp, assistant professor of atmospheric, oceanic and earth sciences, and Benoit Van Aken, associate professor of chemistry and biochemistry.

Photo by Evan Cantwell/Office of University Branding

One defining feature of PEREC-and the reason why this team was awarded the NSF grant-is its historical record of Gunston Cove water samples dating back to 1984. That data is invaluable in a project like this, as it gives the researchers points of comparison. And prior to receiving the NSF grant, the team was already taking samples, with support of seed funding from the College of Science, to start tracking the effects of the sewage spill as early as February 2026.

"We have 11 different sampling locations where we sample water quality and organisms each month," said Fowler. Their partners in the Potomac River Keeper Network, the Smithsonian Environmental Research Center, and others are also aiding in sampling along the river.

Water quality monitoring includes standard measures such as temperature, salinity, clarity, and nutrients. The team is including a few additional measures. Checking for traces of PFAS, the chemical used on Teflon pans, is one addition, led by Van Aken. Hupp is monitoring heavy metals.

The team is also utilizing new technology: environmental DNA (eDNA). Macro- and microscopic species leave detectable traces of DNA as they interact with and move through the environment. Through an environmental sample-such as a water sample-researchers can detect the presence of the organism in an area from their DNA and map biodiversity without needing to directly sample or see the organisms themselves, from phytoplankton to fish.

"Typically, if you have big, severe, acute disturbances like this, you'll expect to see reductions in diversity," Salerno said. "So, we're going to test that theory, as well as examine if those changes affect the food web."

Photo by Evan Cantwell/Office of University Branding

Funding for the project ends in May 2027, though PEREC's standard water and organismal sampling in Gunston Cove, funded by Fairfax County, will continue to keep building their extensive library of historic data.

A second component of the NSF grant is tying this research into teaching and outreach-a good fit for PEREC, whose key pillars include educational outreach. Findings from this research will be incorporated into the Meaningful Watershed Educational Experiences (MWEEs) program with Fairfax County Public Schools, led by environmental science and policy professor Cindy Smith. The team has also recruited more than 10 graduate, undergraduate, and high school student researchers. They will be trained in sampling, laboratory analysis, data interpretation, and science communication, and paired with graduate student mentors for additional support.

"The outcomes of this research could have a significant impact on how organizations prioritize and allocate funding in the future. In addition, the opportunity for students to gain hands-on field and/or laboratory experience through such a high-profile project would be an invaluable professional experience and meaningful addition to their resumes," said Fowler.

Photo by Evan Cantwell/Office of University Branding

Contaminated drinking water reservoirs and disease spread as a result of a large sewage spill in a public water source are, of course, top concerns. But Fowler and Salerno both note the cultural value of the river as well, and the importance of keeping it clean.

"There's been a cultural shift over the past few decades that has increased regional interest in the waterfront," Salerno added. "More and more, people want to use these water systems for recreation, which means there's growing interest in the water being clean and in conserving the ecosystem."

"The Potomac is known as the 'Nation's River' because it flows through the heart of the nation's capital," said Fowler. "It's history also played an important role in raising awareness about the nation's water pollution crisis and the need for stronger protections."

The co-PIs noted that none of this work would be possible without continued collaboration and cooperation amongst the PEREC researchers and faculty.

"This grant is the culmination of years of expertise, effort, and collaboration," said Salerno. "We all specialize in different areas, with unique strengths and research backgrounds. But the river is what brings us together."

Photo by Evan Cantwell/Office of University Branding

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