GERTRUDE STEIN to the contrary, there is a there in Oakland, Calif., at least this month, while the International Sculpture Conference is in full biennial stride. Two summers ago, Washington was the busy conference site with more than 100 pieces of sculpture exhibited out-of-doors throughout the city and more than 40 indoor sculpture exhibitions.

At the time, one of the curators said her main hope for the conference was that "people will grow fond of these artworks, and miss them." Certainly many of the temporary installations here were memorable, inside and out: Charles Simonds' tiny ceramic pieces installed on a window ledge of the original Smithsonian building, castles on a castle; the dark, evocative and also miniaturized world created by Anne and Patrick Poirier in an out-of-the-way gallery near North Capitol Street; a slope-hugging "musical" sculpture by Doug Hollis, in fact more inviting to the eye than ear, out at the National Arboretum; Rockne Krebs' breathtaking laser structure, "The Source," paying stupendous tribute to the eloquent spaces of L'Enfant's city.

May Oakland be so lucky in the artworks that it too, in time, will miss.

Here in Washington there actually exist a few more tangible reminders of the sculptural summer of 1980. Unlike paintings, sculptures often are costly to make and to move. Artists will come into a city and lug their sculptures along, often on huge flatbed trucks, or will build them on the site out of weighty stuff. To dismantle such pieces and cart them away presents a huge economic and logistical problem. It is often more convenient simply to leave them where they are, especially when they look good and people seem to like them.

This is what happened with J. Seward Johnson's monumental crowd-pleaser, "The Awakening," near the tip of Hains Point; Nancy Holt's graceful steel cupola on the Ellipse near the Corcoran Gallery of Art; Beverly Pepper's giant steel columns on a vacant lot along Independence Avenue; and Lloyd Hamrol's geometric abstraction, made of huge wooden beams, in a glade of Rock Creek Park, near the Shoreham.

In its own way, each of these pieces demonstrates how much sculpture can do to enhance and enliven city spaces. Johnson's sculpture has become something of a tourist attraction. Children, especially, love to climb upon the aluminum limbs and head of the giant as it struggles to escape from the ground. The kids are unbothered, of course, by parents who say the subject is grisly, despite the title, or by a critic's objections that, judging from the size and placement of the fellow's exposed parts, his buried body, once free, will be hopelessly deformed.

The other works are more subtle in their effects and surer in their grasp of particular places. Holt's gently disturbing piece, a double-edged reminder of jails and pretty park furniture, looks as if it had been in its place for years, an effect enhanced by the Park Service gardeners who tend to the circle of red geraniums surrounding the artwork. Pepper's robust, 30-foot-high rusted steel columns, each with its distinct physical and psychic profile, add four succinct notes of raw industrial energy (and preindustrial totemism) to the bureaucratic blandness of the neighborhood on the south side of Independence Avenue.

Hamrol's piece is a wonderful visual surprise you get rounding a bend in the footpath in Rock Creek Park. It rises up like a plant out of the sloping grassy turf, and yet its simple geometry obviously is man-made: a series of x-shapes, each made by two intersecting logs, arranged atop each other in a spiral form. It makes its mark, and also makes a comfortable vantage point from which to observe the interesting comings and goings of the city.

We could use many more works like these in our public spaces, but can be thankful for what we've got. They are, after all, temporary loans. None is likely to be here two summers from now.