Los Angeles County officials are warning residents to be careful swimming, surfing, and playing in ocean waters due to possible contamination caused by storm drain discharge.

The ocean quality rain advisory was issued Monday for all L.A. County beaches and will stay in effect until Thursday, according to the Los Angeles County Department of Public Health.

Rain can contaminate waters, especially near discharging storm drains, creeks and rivers due to trash, and other public health hazards from city streets being washed into them.

“Individuals who enter the water in these areas could become ill,” health officials said in the advisory.

Recorded information on beach conditions is available on the county’s beach closure hotline at 800-525-5662.