Expanded testing finds Potomac River back to normal after January sewage spill, DC Water says

The Potomac River shows no signs of lasting damage from January’s massive sewage spill, DC Water said this month after completing a broader round of water testing.

In a statement released Oct. 7, the utility said samples checked for oxygen, nutrients and metals all came back within the river’s normal range. The results add to months of bacteria testing that had already shown the river recovering from the January collapse of the Potomac Interceptor, a major sewer line that carries wastewater toward the District.

The spill

The interceptor ruptured on Jan. 19 and released more than 240 million gallons of sewage into the river, NBC4 Washington reported. A February memo from the Metropolitan Washington Council of Governments put DC Water’s estimate at about 243 million gallons. Crews eventually diverted most of the flow into the drained C&O Canal, which carried it back into the sewer system, and the line was not fully repaired until March, according to NBC4.

D.C. lifted its public health warning for the river after daily testing that began in late February showed E. coli had fallen to safer levels, NBC4 reported. In May, DC Water said hundreds of samples taken since mid-March showed bacteria had returned to normal levels, and it laid out plans to restore the affected stretch of the C&O Canal.

What the new tests measured

Beginning in August, DC Water expanded its monitoring beyond bacteria to measure dissolved oxygen, nutrients and metals, all of which matter for the health of the river and the fish and plants that live in it. The utility collected samples in five rounds at six sites in Maryland, both upstream and downstream of the overflow point. Every result fell within the river’s usual range, DC Water said.

“These results are reassuring,” DC Water Interim General Manager Matthew T. Brown said in the release.

Before the expanded testing, crews had sampled daily for E. coli at as many as 10 locations for more than six months, according to the utility.

Lingering effects

Even as tests improved, some river-based businesses continued to feel the effects over the summer because many people still viewed the water as unsafe, NBC4 reported. FOX 5 DC reported that residents it interviewed near the river welcomed the update but said they wanted to stay informed.

DC Water declined FOX 5’s interview requests, citing ongoing litigation tied to the collapse. FOX 5 has reported on a class-action lawsuit filed after the spill.

What’s next

DC Water has said a second phase of restoration along the C&O Canal, including replanting native vegetation, regrading wetlands and repairing the canal’s clay liner, was expected this fall. District Times could not confirm the current status of that work.

Full results from the expanded testing and the daily E. coli sampling are posted on DC Water’s water quality monitoring page, according to the utility and NBC4.