The final program by the Washington Ballet in its current spring series at Lisner Auditorium yesterday found the company in excellent shape. The troupe is small and its means extremely limited. What it is doing, however - exemplified by this program and the standard of its execution - is of prime importance to the future of classical ballet in this city.

Take the opening performance of Balanchine's "Concerto Barocco," for instance, as staged by Victoria Simon. This is a choreographric masterpiece and a heavy demanding one. Yet, against all odds and despite a too confining stage, inadequate lighting, recorded music and the inexperience of the dancers, the ensemble of 11 managed a very presentable account of the work, one that got to the structural and stylistic heart of the matter.

An even more impressive accomplishment was the world premiere of "Variations Serieuses" by Choo San Goh, the 29-year-old native of Singapore who joined the company as resident choreographer last year and has since been enriching its repertoire by leaps and bounds.

Like the previous five works by Choo the Washington Ballet has shown us, the new opus bespeaks that rarest of gifts - a natural feeling for the expressive possibilities of the classical ballet language. Set to Merdelssohn's solo piano composition of the same title, the work is perhaps modeled a little too closely on Jerome Robbins' "Dances at a Gathering" and other recent "piano ballets." All the same, it has passages of marked and memorable originality. The choreography proceeds from the music with an easy, prolific logic, yet it is never slavishly bound to the score. Exits and entrances are beautifully designed to poetic effect. The movement is bristling and complex at times, yet it also leaves room for stillness and meaningful pause.

Not all of the variations sustain themselves equally well, but the piece as a whole has more than one high point, including a wonderfully conceived bipartite solo (splendidly danced by Patricia Miller) that goes over the same musical ground Twice from contrasting perspectives.

Guest artists Kevin McKenzie (a WB alumnus) and Denise Jackson gave a handsomely polished rendering of Balanchine's "Tchaikovsky Pas de Deux." The remarkable aspect of the program, however, was that it included four works by youthful choreographers, counting in Choo's "Variations." The other three - McKenzie's "Essay," Loyce Houlton's "Wingborne," and Salvatore Aiello's "Sola," were rather pale and derivative in comparison. Nevertheless, it is refreshing to see so much relatively new work from unfamiliar creative sources, and all these pieces served as fine vehicles for the display of the talented dancers involved - Madelyn Berdes, Patricia Berrend, Caroline Iura, Brian Jameson and Dana Leubke.

The progress of these and other company dancers - James Canfield, for example - is further evidence of the troupe's present health. All the same, the matinee audience was surprisingly small. It would be a great pity if the ballet public lets the company down now, just when it is beginning to realize its promise and fulfill its significant artistic mission.