The winter storm moving through San Diego County is likely washing billions of gallons of pollutants into local waterways.
The San Diego County Department of Environmental Health has already issued a warning for swimmers to stay out of coastal waters for 72 hours after the rain stops.
This year's dry winter actually means there's more pollution out there than during a normal storm event.
"Because we've had a lack of rain in San Diego," said Mark McPherson of the Department of Environmental Health. "Any pollutants that built up on our streets in our gutters, with this rain, they are most likely going to be washed into our creeks and our rivers that actually drain in the ocean."
Pet droppings, oil and pesticides are just some of the things washed out into the ocean during storms.
The only protection swimmers have, according to McPherson, is to stay out of the water until the pollution is diluted enough to make it safe.