KAREN NOEL and Lothar Witteborg, from the two-tiered dock of their house, can see the lake, with its fountain in the center, the plume of water spouting 50 feet into the air.

In the winter, the lake freezes over. Skaters and migratory birds -- Canada geese, black ducks and mallards -- parade upon the ice.

In summer, there is swimming, fishing and boating in sailboats, rowboats and canoes, as well as floating vehicles less easily categorized -- lawn chairs on pontoons, for instance.

Those who think a "planned community" is either a retirement village or an in-town Club Med may find it hard to believe that this idyllic spot is on the shores of Lake Anne, in Reston, Va.

Delighted with their home on the lake, Noel and Witteborg find Reston's urban flavor equally appealing. (The so-called "new town," built from scratch near Washington Dulles port, is now approaching 21.) For them, the community offers the kind of mix its planners intended.

The plaza, also on the lake, "is rather European," says Witteborg, "guitars plunking as you pick up your groceries or your laundry."

1977, to take a job with a local architect. Witteborg followed in 1980, to marry Noel, who, in the interim, had opened a Reston architectural firm of her own, Stanmyre & Noel. Witteborg joined Alexandria-based Design & Production as design director. A museum exhibit designer, he has traveled all over the world.

Initially, the couple lived in Noel's condominium in a Reston high-rise. In search of additional space, they purchased their current residence last August -- an airy, three-story town house in Waterview Cluster, one of Reston's earliest developments. The gray-green, red-roofed brick structure, with large glass sliding doors and windows on the back, was designed in 1964 by Cloethiel Woodard Smith. An exterior spiral staircase had been added to descend from an outside balcony off the living room on the second level to a narrow deck below.

Most of their remodeling in recent months has focused on expanding the two-bedroom dwelling visually, with Noel acting as the architect as well as general contractor. On the ground floor, for example, a solid door blocking the view between the entrance foyer and the library was removed so that the lake can be seen from the front of the house to the back.

One flight up, the waist- high partition that separated the dining room from the kitchen was eliminated; the old dining room was incorporated to create a larger and less formal open-plan kitchen. Fireplaces on both levels were streamlined by removing dated, tacked-on, mantels.

The outside staircase, adorned in summer by geranium-filled flowerpots, now leads to a unique doc that Noel designed to replace the original deck. The detachable, lower tier of the dock turns into an 8-by-15-foot motorized barge. From time to time the couple has a cocktail party on the barge or uses it to cruise over to the nearby plaza for a concert or to do their shopping.

The interior of the house is a study in beige, white and cinnamon. It reflects its designer owners' preference for clean lines and open spaces.

town house is an up-to-date setting for the couple's respective collections, now combined -- Noel's baskets, garden books and contemporary hand-crafted kaleidoscopes plus the kilim rugs and boxes Witteborg has gathered in the course of his far-flung, on-the-job travels.

In addition to collecting, Noel and Witteborg share a penchant and a talent for arrangement and display. "Fortunately," says Noel, "our interests are compatible, not competitive."

"(Reston) is a cradle-to- grave kind of thing," says Witteborg. "You can get a starter apartment, a town house, a small or large detached house, and when the kids are gone move back into an apartment, all in the same neighborhood."

Their neighbors in the cluster have become good friends -- a diverse group including other architects and designers as well as a retired State Department official and his wife, who have lived there since the '60s, a television producer and an airline pilot. "All my life," says Witteborg, "I have lived in places where I never knew my neighbors. Not any more."

Summing it up, Witteborg has the last word. "Can a world traveler find happiness in a place called Reston? The answer, emphatically, is 'Yes.'