County environmental health officials issued a water contact advisory Wednesday for all coastal beaches and bays due to contamination from urban runoff following rainfall.

The Department of Environmental Health warned swimmers, surfers and other water users that levels of bacteria can rise significantly in coastal waters, particularly near storm drains, creeks, rivers and lagoon outlets that discharge urban runoff. Water contact should be avoided for at least 72 hours following a rainstorm, according to the county.

The general rain advisory for urban runoff contamination applies to beaches from San Onofre State Beach south to Border Field, including Mission Bay and San Diego Bay.