About 40 million people in the U.S. live in a community with a combined sewer system, where wastewater and stormwater flow through the same pipes. After heavy rains, when pipe capacities are reached, the overflow sends raw wastewater into the rivers instead of to a treatment plant. Federal regulations, including sections of the Clean Water Act, require municipalities such as Washington to reduce at least 85% of this pollution or face steep fines.
To get into compliance, Washington launched a $2.6 billion infrastructure project in 2011. DC Water’s Clean Rivers Project will eventually build multiple miles-long underground storage basins to capture stormwater and wastewater and pump it to treatment plants once heavy rains have subsided.
The Anacostia tunnel is the first of these storage basins to be completed. It can collect 190 million gallons of bacteria-laden wastewater for later treatment, said Moussa Wone, vice president of the Clean Rivers Project.
Climate change is causing more intense rainstorms in Washington, so even after construction is complete in 2030, Wone said, untreated stormwater will still be discharged into the river, though much less frequently. “On the Anacostia, we’re going to be reducing the frequency of overflows from 82 to two in an average year,” Wone said.
But while the Anacostia sewershed covers 176 square miles, he noted, only 17% is in Washington. “The other 83% is outside the District,” Wone said. “We can do our part, but everybody else has to do their part also.” Upstream in Maryland’s Montgomery and Prince George’s counties, miles of sewer lines are in the process of being upgraded to divert raw sewage to a treatment plant instead of the river.
The data shows that poop is a problem for river health — but knowing what kind of poop it is matters. Scientists monitor E. coli to indicate the presence of feces in river water, but since the bacteria live in the guts of most warm-blooded animals, the source is difficult to determine.
“Is it human feces? Or is it deer? Is it gulls? Is it dogs?” said Amy Sapkota, a professor of environmental and occupational health at the University of Maryland.
Bacterial levels can fluctuate across the river even without rainstorms. An Anacostia Riverkeeper report found that in 2023 just three of nine sites sampled along the Washington portion of the watershed had consistently low E. coli levels throughout the summer season.
Sapkota is heading a new bacterial monitoring program measuring the amount of E. coli that different animal species deposit along the river. The team uses microbial source tracking to analyze samples of river water taken from different locations each month by volunteers. The molecular approach enables scientists to target specific gene sequences associated with fecal bacteria and determine whether the bacteria come from humans or wildlife. Microbial source tracking also measures fecal pollution levels by source.
“We can quantify the levels of different bacterial targets that may be coming from a human fecal source or an animal fecal source,” Sapkota said. Her team expects to have preliminary results this year.
The health risk to humans from river water will never be zero, but Sapkota said, based on her team’s research, smart city planning and retooled infrastructure could lessen the level of harmful bacteria in the water.
“Let’s say that we’re finding that actually there’s a lot of deer fecal signatures in our results,” Sapkota said. “Maybe this points to the fact that we need more green buffers along the river that can help prevent fecal contaminants from wildlife from entering the river during stormwater events.”
So, deer aren't going to walk (or jump fences) into the green buffers, eat it and poop there? I don't think you understand deer.
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