After nearly 40 years, city and federal officials plan to clear the air by the C&O Canal.

Ray Fletcher doesn’t need environmental scientists to tell him why the Chesapeake & Ohio Canal National Historical Park stinks. By necessity, he’s an expert on the putrid air himself. With his brother Joe, he runs Fletcher’s Boat House, renting canoes and fishing equipment to park visitors—or trying to rent them, anyway.

Year after year, he says, the same thing happens: Would-be boaters take one whiff of the wind and develop second thoughts. It’s been Fletcher’s job to explain to them that the Potomac River and the canal are not to blame, as most people assume. The skunky air emanates from the Potomac Interceptor, an underground sewage system that carries some 50 million gallons of wastewater per day from suburban Maryland and Virginia and parts of the District down to the Blue Plains Advanced Wastewater Treatment Plant in Southwest D.C.

Ever since the D.C. Water and Sewer Authority (WASA) opened the interceptor, in 1964, the stench of human waste has drifted through the park near the Palisades neighborhood, tainting it by association. Earlier this month, the National Park Service released an environmental assessment saying what Fletcher has known all along—that “the nuisance odors from the [interceptor] affected…enjoyment of the surrounding national historic landscapes”—and laying out a long-term plan for controlling the smell.

In essence, the Potomac Interceptor is a river of wastewater, conveyed downstream by gravity. As the pipeline cuts through the park, there are places where it drops down vertically, creating waterfalls of tumbling sewage within. The churning kicks up pockets of gas, which can be dangerous and corrosive if left in the pipeline. Therefore, at approximately 30 spots throughout the park, the interceptor belches out clouds of fetid gas through release vents. One of these chimneys is located a few hundred feet from the boathouse.

“There were times in the past when the smell got so bad,” says Fletcher, “it just about knocked you over.”

To deal with “sewer air influence” zones, WASA has pledged approximately $3.7 million for long-term odor abatement, including the construction of four “odor control facilities.” Euphemisms aside, the new buildings would suck gases out of the sewer pipes and blow the pungent plumes through filters. There, beds of activated carbon would strip the gas of hydrogen sulfide—the compound that, according to John Trypus, an environmental engineer with WASA, lead engineer on the project, accounts for “98 to 99 percent of the odor generation.”

The report and abatement plan come three years after local environmental groups sued WASA to get it to do something about the smell. In 1999, representatives of the Potomac Conservancy, the American Canoe Association, and the Canoe Cruisers Association filed suit in U.S. District Court, accusing WASA of violating the terms of its permit for the interceptor. Shortly thereafter—some 35 years after the sewer opened—WASA launched a two-part study of the odor and took interim steps to control it, such as dangling buckets of sulfur-absorbing gel into the pipeline at strategic locations.

Representatives for the environmental groups are currently meeting with WASA attorneys, as they have off and on since the suit was filed, to negotiate a settlement. But the talks have yet to end the dispute over the smell. “We just want to make sure that they put this plan into something that is legally binding,” says David Bookbinder, the lead attorney for the plaintiffs. “If we were to drop our lawsuit and walk away, they would probably just shelve their plans and wait for someone else to sue them.”

The history of the interceptor supports Bookbinder’s skepticism. In the early ’60s, when WASA first proposed channeling raw sewage just below the surface of a national park, some D.C. residents objected. So the initial permit granted by the Park Service, dated April 26, 1962, addressed odor concerns directly: “All vent structures shall either be located off United States property or shall provide for odor controlled carbon filters.”

Nevertheless, when WASA submitted its initial vent designs, the filters were missing. In June 1962, Raymond L. Freeman of the Park Service sent a letter to James W. Head Jr., the chief engineer of the Potomac Interceptor, reminding him of the odor-control requirements. “It is requested that your office take the necessary action to revise the vent structures, located on park land, to accommodate carbon filters,” wrote Freeman.

The drawings were revised within a week to include a carbon filtration system. Whether the filters were actually incorporated into the vents is unclear. Trypus declines to say, citing the pending lawsuit as his reason for silence.

Bookbinder, on the other hand, says that the carbon filters did get built into the vents at the time. Unfortunately, he claims, they were never maintained. Carbon filters must be frequently washed and regularly replaced. Otherwise, hydrogen sulfide and other chemicals clog the pores, rendering the system useless.

About two years ago, in the course of their interim smell-control efforts, WASA officials tinkered with the vent in the woods near Fletcher’s Boat House. Did they simply change the filters, as they should have been doing for the past four decades? They won’t say.

Whatever they did, the change quickly registered in Fletcher’s nose. “The odor was diminished,” says Fletcher. “It’s been much, much, much better. Occasionally, on hot, still, summer evenings, you’ll catch a whiff. But that’s OK. I can live with that. It’s tolerable.”

Recently, though, Fletcher says the smell has seemed to be gathering strength again. So he looks forward, he says, to the day WASA installs a long-term filter facility near the boathouse. “This will be great for everyone who uses the park,” says Fletcher. “People will be able to come here, and it will actually smell like how a national park is supposed to smell.” CP