The Rev. William E. Swing, 43, rector of St. Columba's Episcopal Church here, has been elected as bishop of the Episcopal Diocese of California.

He will succeed the Rt. Rev. C. Kilmer Myers, who announced his decision to step down last year. The diocese, headquartered in San Francisco, is considered one of the most influential and in recent years has been among the most controversial predecessor was Bishop James Pike.

The Washington priest was elected on the 15th ballot late Saturday by the California Diocesan Convention when his nearest rival for the post, the Rev. George Hunt, withdrew and asked the Convention to elect Swing "by acclamation."

Swing has been at St. Columba's at 42nd and Albemarle NW, since 1969. He has served on the Diocesan Council and the Standing Committee of the Washington Episcopal Archdiocese. For the last three years he has been president of the latter body, which is the most powerful elective unit within an Episcopal diocese.

A strong advocate of opening the Episcopal priesthood to women, he worked for that cause through numerous committees and groups when that was an issue for the church. In addition, he offered St. Columba's church as the site for a number of events of those controversial years, including the historic ecclesiastical trial of a fellow priest, the Rev. William A. Wendt, who had permitted a woman to function as a priest before the national church officially sanctioned it.

Swing has been concerned with the problems of mental health and the mentally ill and involved in efforts on behalf of the aging. He is chaplain at Friendship Terrace, a senior citizen's development adjacent to St. Columba's.

According to Episcopal church practice, Swing's election must be approved by the standing committee and bishop of every other diocese throughout the country before he can be formally consecrated and installed as bishop. Except in rare cases, such approval is perfunctory and almost always granted.

The Washington priest is married to Mary Taylor Swing, who is on the staff of the College of Preachers. The couple has two children: Alice, 16, and William, Jr., 14. CAPTION: Picture, WILLIAM E. SWING . . . at Episcopal church since 1969