Mildred Stombs Warenskjold, 86, a producer and director of several opera companies in the San Francisco area before moving in 1952 to Los Angeles, where she was director of the Immaculate Heart College Opera Workshop for 13 years. She also organized several groups of singers who performed locally in chamber operas, almost all in English, which she wrote herself. One of her groups was the first U.S. organization invited to the Waterford Festival in Ireland. Among her pupils was her daughter, lyric soprano Dorothy Warenskjold, a star of the San Francisco opera company and others. In Northridge on March 9.