Runoff has forced the closure of two local beaches and prompted the Orange County Health Care Agency to issue a beach advisory because of the rain.
"This is weird for this time of year," said Monica Mazur, an environmental health specialist in the agency's environmental health division.
The agency closed the Balboa Bay Club beach last week, then the northeast end of Newport Dunes near the pedestrian bridge this week because of storm runoff, which can include fertilizer, motor oil, animal waste and litter.
Levels of bacteria can rise significantly in ocean and bay waters close to storm drains and at the outlets of creeks and rivers, according to the agency.
The elevated levels can last for at least three days, depending on the intensity of the rain and volume of runoff. During this time, swimmers and beach users are advised to stay out of the water near storm drains, creeks and rivers and avoid contact with any runoff on the sand.
To report an illness or sewage spill, or for more beach closure information, call (714) 667-3752.