A PERSON seated at a desk deep in the heart of this superpower capital can, within 30 minutes, be re-seated in a kayak deep in a canyon, shooting some of the toughest white-water rapids in the United States.
For most, the Potomac River is a broad and quiet reflector of history as it passes alongside this city. What surprises even many who live here is that the Potomac cuts a swath of wilderness - full of turkeys and turtles, herons and herring - right through the metropolitan sprawl of the District, Maryland, and Virginia.
It's a brand of surprise, sometimes happy, sometimes not, that has always characterized the Potomac.
For example, a British explorer encountering the mouth of the river in 1585 wrote in delight that the fish were so abundant, they could be caught with frying pans. And it is a surprising contrast to see the headwaters of the Potomac burbling up in the misty beauty of a West Virginia glade only to find that just downstream fish can barely live because the acids from old coal mines contaminate the water.
Lacking distinction as the nation's longest or shortest, cleanest or dirtiest, the Potomac is the quintessential all-American river.
It has flowed through US history: From George Washington's time to John Brown's raid at Harper's Ferry; from the bloody Civil War battle at Antietam to political sabotage at the Watergate towers.
And it has flowed through the classic environmental cycle: deteriorating from a rich Indian-trading thoroughfare of centuries past to what Lyndon Johnson called a "national disgrace" of pollution, and back again as a near-pristine and sought-after place to be.
"The river is an example of society finally realizing rivers are not designed to carry our waste away," says Lee Zeni, executive director of the Interstate Commission on the Potomac River Basin.
He says that since President Johnson pledged to clean up the river, $5 billion has been spent publicly and privately on clean-up and education efforts.
Education efforts are so widespread that it's not unusual for a homeowner miles away from the river to be scolded by a passerby for gardening techniques that might send soil or toxic chemicals into the Potomac system.
"The Potomac is unique in these qualities: It is surprisingly pristine and wild this close to a sprawling metropolitan area, and it has no large-scale dams," says Beth Norcross, director of legislative programs at American Rivers, a national river-conservation organiza- tion. "Certainly, it is a river under stress, but it is in remarkably good shape."
Indeed, those who live and work along the 380-mile river heartily attest to that.
Tom Hobbs had his first tour of duty in the National Park Service in Washington in 1970. He vividly remembers being trapped in rush-hour traffic that summer on a Potomac River bridge: "It was like being in a septic tank, the stench was unbelievable."
The change in the river is startling, says Mr. Hobbs, who has returned to the area as the superintendent of the Chesapeake and Ohio Canal, the national historical park that parallels the Potomac River for 185 miles between Washington and Cumberland, Md.
"It's an incredible turnaround. It really died and came back. There may be no comparison with Western rivers with water coming right out of glaciers, but it rates well among Eastern rivers," says Hobbs.
The C&O Canal was envisioned by George Washington as a major commercial-transportation link to western frontiers. But it has played a key, if unintended, role as an environmental buffer, helping to make the middle section of the river the healthiest part.
Bill Sonntag, a waterman who plies the tidal Potomac near the first colonial settlement in Maryland at St. Clements Island, sees a direct link between the strict environmental laws of the 1970s and '80s and a visible change in the food chain on the river. As agricultural runoff and city sewage were brought under control, life-sustaining water grasses have returned, and in turn so have diverse fisheries, he says.
Kent Fuller, the director of the Appalachian Environmental Laboratory at the University of Maryland in Frostburg, recalls growing up in Cumberland, down river from paper, tire, and textile plants and the abandoned coal mines' seeping acid. Fishing wasn't even a consideration in the polluted waters, he says.
But state and federal mine cleanups, stricter federal and state environmental regulations, and a new dam at Bloomington, Md., that had the unintended-but-welcome effect of reducing water acidity have changed the scene, says Mr. Fuller.
"If the river continues improving as it has, we'll develop into one of the premier fishing areas in the country."
In the depressed Appalachian region of West Virginia and Maryland where many factories have shut down, state officials say a heavy investment in environmental controls will foster a recreation industry on the Potomac that would boost the economy.
The color of the Potomac gets slightly reddish-brown upstream of Cumberland, just before the smokestacks of the Westvaco Corporation's Luke, Md., magazine paper mill comes into sight.
But today - unlike most of the 103 years of the mill's operation - Maryland and West Virginia authorities say it is safe to fish the waters around the plant (except for bottom-feeding fish, which may be contaminated by toxic dioxin built up in sediment after years of bleach discharge from the plant).
The Cumberland area's largest, most stable employer, Westvaco has invested heavily in environmental controls - especially since dioxins were discovered here in the late 1980s, says Roger Dandridge, manager of the mill.
While the plant is here to stay and Westvaco-developed technology has removed dioxin from plant discharges, he says, expansion of business here may be limited because of the costs of stringent regulations Maryland has brought to bear in the Potomac cleanup.
"We have competitors who play on an entirely different playing field," he says.
While there is universal agreement on the Potomac's progress, environmental groups - particularly those concerned with the delicate balance of the Chesapeake Bay - say it is not enough.
The Anacostia River, which begins and ends within urban environs, for example, feeds into the Potomac at Washington almost as much pollution as has been cleaned out of the Potomac, say some environmentalists.
While pollution from agriculture and development - such as fertilizers and pesticides - and erosion runoff - are still a problem on the Potomac, Mr. Zeni says the Anacostia River cleanup is now considered a major component of the Potomac cleanup itself.