The words like a lockhouse covered with time,

Live on for us in an old man's mind,

Never no more, on the C&O Canal Line . . . .

-- "C&O Canal," by John Starling

The flood of 1924 knocked the final hole in the commercial life of the Chesapeake & Ohio Canal, a 184-mile waterway along which barges had operated for more than a century.

The railroads had long been in place, and there was no economic reason to rebuild. The days of running dusty Cumberland coal along the water were over, and a Maryland institution was dead.

But Jesse Anderson Swain and his family, who had operated Lock 21 since 1909 from the stone lockhouse that went with the job, had hogs, chickens and cows to tend, bottom land to till, the adjacent Potomac River in which to fish and trap, and free lodgings, with the landlord C&O Canal Co. out of business. The Swains stayed on.

Sixty-one years, three generations and three floods later, the family is still there, two miles north of the upper-crust suburb of Potomac, happily ensconced in the only original C&O Canal lockhouse continually inhabited since the waterway was completed in the 1850s. The house is warm, modernized inside, neat as a rectory and rich with life, and the Swains aren't leaving Swain's Lock anytime soon.

"It's the prettiest place I've ever been in my life," said Virginia Swain, who moved in at age 15 after marrying Jesse's son, Robert Lee, and has lived nowhere else in the 55 years since.

"I was no river rat until I got mixed up with the Swains," she said, "but I wouldn't trade what I've had with anyone, not even with Mr. Reagan in the White House."

Because she arrived six years after the locks closed, Virginia Swain never got to hear the bugle warnings of boatmen approaching in the days of commerce nor the lockman's shouted response, "Lock ready!" But over the years she accumulated river memories of her own, as well as four children. She and her son Fred and his wife and teen-aged daughter share the lockhouse now.

The floods were the worst, she said, peering warily out the living-room window toward a cold rain and the river. Her first was 1936. She saw the muddy water rising, but her father-in-law said it wouldn't reach the house.

"He wouldn't let us move a thing," she said. "He kept saying, 'It won't come in the house,' even when I could see water coming under the door."

Three brass buttons on the upstream corner of the house mark the flood levels of 1936, 1942 and the last one in 1972, when tropical storm Agnes turned the Potomac into a roaring, brown maelstrom.

But '42 was the meanest, when the Swains lost two cars and some livestock. A man standing with arms stretched overhead can't reach the brass button marking the 1936 flood height when the water got within two steps of the second floor.

When the floods receded, they left waist-high mud in the living room, parlor and kitchen. It was a battle to shovel it out fast, because once it dried you'd never get it all out.

But when the Potomac flooded, the Swains found plenty of friends. "We don't sleep when the river's raising," said Virginia Swain. "We're up all night, watching it, checking how fast it's coming up. Our friends keep calling: 'When do you want us to bring the trucks?' "

It's been only since 1952 that the Swains have had electricity and a telephone. "We used to live by kerosene lamps," said Fred Swain, who was born in 1937. "It was a big deal when we got Coleman lanterns. Then you could really see."

Virginia Swain, who could remember how her father-in-law died in 1939 and she sat for four hours with the body before anyone came to help, demanded the phone and electric power be hooked up after her husband had his first heart attack in 1952. He died in 1967.

The whitewashed stone house had been a step up for her when she arrived in 1930. She had grown up in a bungalow in the hollow where the Beltway roars past River Road. "That was a deep hollow in there," said Fred Swain. "You can't imagine how much fill they put in to build the Beltway."

Virginia Swain fetched water morning and night from the spring on River Road, and she walked to school. When she moved, she said it was like living in the city, with River Road just up the lane, a Seneca red sandstone house to live in and a truck to ride to the store.

The lockhouse was rough back then, with plaster interior walls simply following the lines of the rock exterior. But Fred Swain, who works at the Bethesda Naval Medical Center, framed out the interior and insulated it and put sheet rock in it, and today the inside walls are as plumb as a tract house's. And plumber than some.

The Swains run a concession for the National Park Service, which owns the land now. They rent out canoes and boats, many of which Fred Swain built; rent bicycles, and sell minnows and worms to anglers and refreshments to the summer throngs that flock to the reconstructed towpath, the rebuilt canal and the ageless river beyond.

During the warm seasons, the Swains are up and about, often working from 6 in the morning to 8 at night. Now that winter has descended, they are content to settle in the warmth of the lockhouse, doing much of nothing, enjoying a respite from the demands of the busy summer months.

Fred Swain says he's never managed to make a living from the concession, but it wasn't for lack of trying. "When you get up in the spring and the trees are budding, the sun's shining, the birds are singing and the river's rolling by, you wonder why in the world you'd want to go to Bethesda."

His mother feels the same. "I've lived here all my married life," she said, "and I don't want to leave until the day I die."