Official to Retire: Arthur E. Bruington, general manager of the Irvine Ranch Water District since 1979, will retire June 1, district officials have announced. Bruington had served for 29 years with the Los Angeles County Flood Control District before joining the Irvine Ranch district. He is a director of the American Society of Civil Engineers. He will be succeeded by Ronald E. Young, who holds a number of civil engineer degrees and who served as president of the California Water Pollution Control Assn. in 1986. A retirement dinner will be held for Bruington May 29 at the Irvine Marriott.