D.C. lifted an advisory steering residents away from the Potomac River on Monday, six weeks after a pipe collapsed and spilled more than 240 million gallons of sewage into the waterway.
The spill, which was largely contained by a fix installed in the week after it began, temporarily spiked levels of E. coli and other disease-causing pathogens near the spill site and downstream in D.C. waters, according to testing by local authorities and University of Maryland scientists. But water-quality levels in D.C. have since returned below safe recreational limits, aside from typical and expected bumps in bacteria levels following rain and snow, according to the D.C. government’s health and environment agencies.
Officials with D.C. Water, which operates the pipe, say they still do not know exactly what caused the pipe to collapse. D.C. Water CEO David Gadis said at a Thursday community meeting in Bethesda that he thinks part of the cause may have been that the weight of large rocks and boulders used as backfill on top of the pipe when it was constructed may have put too much pressure on it. The pipe’s thinning walls may have also contributed, he said.
As D.C. Water continues its costly repair and environmental remediation process — for which the federal government recently said it would contribute funds — D.C. officials say it is once again safe to fish and boat in the Potomac.
Is drinking water safe?
Yes, the region’s drinking water is safe. In D.C., the drinking water system is separate from the wastewater and sewage pipelines.
The primary intake facility for the Washington Aqueduct, which supplies drinking water from the Potomac to the region, is at Great Falls — upstream from the sewage spill. An intake facility downstream from the break, at Little Falls, was not in operation at the time of the spill and has remained closed since the incident.
Officials with the D.C. Department of Energy and Environment have said that any sewage that entered the Potomac because of the pipeline break “flowed away from the water intake and not toward it.”
Why is D.C. lifting the water advisory?
D.C. health officials say D.C. Water has contained the sewage spill and the city’s water quality has remained at typical levels for three weeks.
“In the D.C. waters, we consider it safe for you to have contact with the Potomac,” said Ayanna Bennett, the city’s health director.
There have been no overflows into the river since Feb. 8, when a glut of non-disposable wipes overwhelmed the bypass system D.C. Water set up to divert sewage from the spill site, the independent utility said. The latest testing data from D.C. Water show E. coli below safe recreational limits at all D.C. locations — and at Minnie’s Island, which is about a half-mile downstream of the spill site.
“As we get away from the event with time and with increasing river flow especially, we’re seeing all those bacteria levels come down significantly,” said Amanda Zander, who is leading environmental remediation efforts for D.C. Water, at the community meeting Thursday.
The bacteria levels do fluctuate and were above safe recreational limits in D.C. sporadically over the past week — but officials say those elevated levels were unlikely to be spill-related. Even without a massive pipe collapse, sewage overflows after rainstorms periodically elevate E. coli levels in the Potomac River.
I live in Virginia or Maryland. Can I go in the water?
Maryland officials said Wednesday that pending further water-quality testing, they plan to lift on March 10 a precautionary closure of the Potomac River’s shellfish harvesting waters that had been in place because of the spill. Officials with the Maryland Department of the Environment said in a statement that recent water-quality monitoring showed there was “no evidence that shellfish harvesting waters” on the river are “affected by the sewage spill further upstream.” After the spill, the agency had closed a small portion of the river — from the Port Tobacco River region down to the U.S. Route 301 bridge, about 60 miles from the site — as a precaution.
Maryland environmental officials also said they collected water samples from the river in Prince George’s and Charles counties and results show bacteria levels “would meet water quality standards for recreational contact.” The department said it will continue to sample water at those locations and at spots near the spill site in Montgomery County.
The Virginia Department of Health said Thursday in an email to The Washington Post that officials had “not made a decision” regarding lifting an advisory issued Feb. 13 and warned the public — and pets — to avoid any recreational activities in the Potomac “out of an abundance of caution.” Margaret Smigo, a programs manager in the agency’s Office of Environmental Health Services, said the department “continues to evaluate the situation” and will provide updates “as they become available.”
At community meetings last week, residents also expressed concern about sewage contamination in the sediment near the spill site and asked for additional testing of that sediment — not just the water — to ensure that it is safe for people to walk around in. Officials said they are taking those concerns into consideration.
Rachel Rosenberg Goldstein, a University of Maryland public health professor whose team has been sampling the water and sediment near the spill site, said Friday that her team is still consistently finding E. coli, along with the pathogen that causes staph infections, in both the water and sediment there.
“Because the environment is so dynamic and we see sediment move into water during precipitation events, it’s important to understand not just what’s in the water itself, but what’s also in the sediment,” she said.
Can I swim in the Potomac?
No, you should not swim in the river. Swimming is already prohibited in D.C. waters without special permission.
Is the water safe for wildlife?
The impact to wildlife is unclear, but regional governments have said they will conduct surveys to examine it.
Untreated wastewater carries toxic chemicals, microplastics, pharmaceuticals, excess nutrients, viruses and bacteria — materials that can harm fish and wildlife. Nutrients can drain oxygen quickly, killing fish and causing harmful algae blooms. In the days after the spill, residents saw dead fish in the water near the spill site — a sign that fish could have been affected, at least in the short-term. The pathogen that causes staph infections can also harm aquatic life, Rosenberg Goldstein said.
How often are officials testing the water?
D.C. Water has been doing daily water-quality sampling at eight sites along the river. D.C.’s Department of Energy and Environment will also up its water-quality testing cadence from weekly to daily starting Monday, the agency announced Friday.
When will the repairs be complete?
D.C. Water said as of Thursday, those repairs are on target to be completed in mid-March. That section of the pipe will also undergo additional rehab that will take nine to 10 months, officials said.
It’ll get warmer soon. What impact will that have?
“Most bacteria prefer warmer temperatures,” said Rosenberg Goldstein, who encouraged residents to look at all available water-quality testing data before getting back to their activities on the Potomac.
She added that warmer weather has been melting snow and tends to come with more rain events — and “all of these things can actually add more contaminants into the water.”
The warmer weather will bring other concerns. Every summer, algal blooms due to higher nutrient levels harm the river’s health. This year, authorities will watch for any additional impacts.
“It’s something that we’re going to be vigilant about,” Adam Ortiz, deputy secretary at the Maryland Department of the Environment, said at Thursday’s meeting.
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