SAN DIEGO — The sporadic weekend rainfall that dumped nearly three-quarters-of-an inch on Lindbergh Field and elsewhere in San Diego has prompted county health officials to issue a general advisory for beach water quality. As is frequently the case following heavy rains, officials from the San Diego County Department of Environmental Health are warning swimmers, surfers and water-based recreation buffs about potential contamination from runoff at beaches up and down the coast. Health officials caution there could be a significant boost in bacteria levels in the water from animal waste, soil and decomposing vegetation. Bacteria levels could be especially elevated in areas situated near storm drains. The advisory is expected to remain in effect for three days after the storm’s passage.