NOT EVERY year in the musical arts discloses significant new trends in composition or performance. In 1981 there was much to enjoy, probably more music than has been performed in the Washington area during any other single year. And, in many areas, the performances were on a remarkably high level.

But, in the language of the viniculturist, it was a year to call "good but not great." In that most important arena--the creative--the trend, strongly noted in recent years, toward a more "lyrical" (Alberto Ginastera's word) or "romantic" style of writing continues to reinforce itself in a number of our leading composers. David Del Tredici's "All In a Golden Afternoon," in its world premiere in Philadelphia, demonstrated again that by no means all the beautiful music dependent on longstanding attitudes toward melody, harmony, rhythm and tone color has yet been written. And the happy parallel that the public is sympathetically open to new music was proven in October when the Chicago Symphony's recording of Del Tredici's dramatic tour de force, "Final Alice," became the nationwide No. 1 best seller in classical recordings, even at a top price for digital records.

In a vastly different world, Ned Rorem's new music for solo cello, noted below, which had its Washington premiere in the Terrace Theater, was equally fascinating in the originality of its extraordinary beauty.

Also outstanding was the emergence of the increasing beauty of the National Symphony Orchestra's playing on a week-to-week basis under Mstislav Rostropovich's enkindling leadership.

Another new vista opened in the imaginative planning of the Kennedy Center's artistic director, Marta Istomin, whose series of Terrace Theater programs are mixing the music of some of this country's greatest composers with some unusual programming of familiar and less well-known solo and chamber music.

Istomin also brought the Mostly Mozart Festival to the Kennedy Center from New York where it has long flourished.

And the Reagans continued the splendid White House concert series started by the Carters; these should become permanent fixtures in any administration.

Among the year's standout performances:

* The Bernstein "Mass," revived for the 10th anniversary of the Kennedy Center's opening.

* The Washington Opera's notable productions of "L'Amore dei Tre Re," "Postcard from Morocco," "La Boheme" and "The Rake's Progress."

* The Metropolitan Opera's brilliant "Mahoganny."

* Paul Callaway conducting the Mahler Eighth Symphony with the Choral Arts Society and the Cathedral Choral Society, the latter celebrating its 40th anniversary.

* Andre Previn's and the Pittsburgh Symphony's two-day English Festival.

* The Gaechinger Kantorei in the B Minor Mass of Bach.

* A stunning new composition: "After Reading Shakespeare," for solo cello by Ned Rorem, magnificently played in the Terrace Theater by Sharon Robinson.

In 1981, as in 1980, Mstislav Rostropovich was the commanding musical personality on the Washington scene.

There was a fascinating new artist in the concert world: pianist Cecile Licad, 1981 winner of the Leventritt Award. Her first NSO appearance was one of the most exciting debuts in seasons.

In 1982: Work is likely to begin on the long-dreamed-of conservatory adjoining the Kennedy Center.