Advisory for all Los Angeles County Beaches in Effect Until Friday, Dec.30, at 4:30 p.m. Because of the recent rainfall, Los Angeles County Health Officer, Muntu Davis, MD, MPH, is cautioning residents that bacteria, chemicals, debris, trash, and other public health hazards from city streets and mountain areas are likely to contaminate ocean waters at and around discharging storm drains, creeks and rivers after a rainfall.