Michigan Opera Theatre opened ts 1976-77 season at David D. Chiera's Music Hall with the world premiere of Washington Square, an opera based on the Henry James novel, with libretto by Kenward Elmslieand music by Thomas Pasatieri. Washington Square (which continúes at Music Hall until Oct. 9) s about a young girl, Catherine Sloper (Catherine Malfitano) who lives with her father, a rich doctor, and her aunt Lavinia (Elaine Bonazzi). She meets Morris send (Brent Ellis) and falls deeply in love with him. Dr. Sloper (Richard Coors) tries to stop the marriage while Lavinia tries to bring it off. Catherine is jilted by Morris and never marries anyone elsc. Operatic masterpieces consist of the epic, the grotesque, and the comic- because music enlarges character and emotion beyond the normal. A bourgeoise domestic tragedy just cannot make it as grand opera. Stil I , Pasatieri's work is welldone. The action flows smoothly, his characters are given time to reveal themselves, and there is everywhere a fine sense of timing. Pasatieri is not a modernist. His music sounds a little like Delius spiced with Berg. Thcre are touches of musical kitsch- cracking' whips during a carriage ride, a quotation from "Casta Diva" when Catherine tells Morris she likes Bellini. All the performances are excellent actor-singers, and the sel (by Santo Loquasto) and the staging (by Nikos Psacharopoulos)work well, though there is too much bumping about during all the scène changes in Act I.