Lewis, who sang for a decade with the Metropolitan Opera and for two decades with the New York City Opera, was known for interpreting the music of living American composers. She originated two signal roles in contemporary opera: the alcoholic Birdie Hubbard in “Regina,” Marc Blitzstein’s adaptation of Lillian Hellman’s drama “The Little Foxes,” and the title role in “Lizzie Borden,” by Jack Beeson.