SHOWBOAT: music by Jerome Kern; book and lyrics by Oscar Hammerstein, II; based on the novel by Edna Ferber; directed by Stone Widney; Craig Hankenson as executive producer; musical direction by Kay Cameron; production design by Michael J. Hotopp and Paul de Pass; costumes coordinated by Sarah Nash Gates; production stage manager Robert J. McNally III; musical staging by Judith Haskell.

Of all the ways to enjoy these lovely late-May evenings in Washington, one of the most delightful has to be to spend the evening at Wolf Trap's open-air theater and hear once again the glorious songs of "Show Boat" -- "Ol' Man River," "Only Make Believe," "Can't Help Lovin' Dat Man," and "After the Ball."

Last night under a full moon, Wolf Trap opened its 10th anniversary season with Eddie Bracken and Lainie Kazan starring in a production of "Show Boat." It will continue through June 1.

The Jerome Kern-Oscar Hammerstein music and lyrics are as fresh, lilting, and touching as they were when "Show Boat" was the spectacular hit of the 1927-28 Broadway season. The story line, adapted from an Edna Ferber novel, spans two generations of life on the Cotton Blossom showboat with gamblers, showmen, workers on the levees and lovers who have bittersweet romances that mostly turn out happily.

How do you stage a 50-year-old classic whose songs are part of America's songbook.You do it with affection, spirit, fine voices to sing those great songs, and great gusto for the clowing acts.

The staging seldom rises above road-company serviceable, and the production needs polishing to smooth some rough edges. But there still is the marvelous music and some high-spirited performances from a large cast.

As Cap'n Andy, the role played by Joe E. Brown in the movies, Bracken does his comic turns with precision timing. When the river boat's production of "The Parson's Bride" is interrupted, he finishes the story with a one-man narration-pantomime. He parries, takes blows and staggers on rubbery legs in a mimed fight. He dies with a final jerk of the leg and coaxes applause from both the stage and real audience.

Kazan, who got her break as the emergency replacement for Barbra Streisand in "Funny Girl" sings "Bill," ringing out all its sad love with husky tones and a catch in her voice. Incidentally it was P. G. Wodehouse who wrote the lyrics for "Bill" and part of the magic comes from the colloquialisms that he used to follow Kern's music.

As Gaylord Ravenal and Magnolia, both the young lovers and their middle-aged incarnations of four decades later, Ron Holgate and Pamela Kalt are attractive actors with rich voices to soar with the lyrical songs of Kern and Hammerstein.

The voice of Robert Mosley flows resonantly with the Mississippi in the great song, "Ol' Man River." Mosley has appeared with the New York City, Boston, San Francisco, and Seattle Opera companies.

There are fine supporting performances from Grace Keagy as Cap'n Andy's formidable wife; Theresa Merritt as Kueenie and D'Jamin Bartlett as the comic Ellie.

The "Show Boat" story spans the years from the 1880s cakewalk on the mississippi levee though the Charleston of 1927. In between there are scenes at the Chicago World's Fair of 1893 and the Trocadero Music Hall on New Years Eve of 1904.

Ravenal loves Magnolia but hurts her again and again. Julie, who has Negro blood, is forced to flee with her white husband under charges of miscegenation. If this is only make-believe on the stage today, in the 1920s it was strong stuff and a departure from the silliness of Viennese operettas and comedies.

"I never thought I'd see 'Show Boat' done again," said one young man as he left Wolf Trap last night.