The San Luis Obispo Public Health Department is advising people to avoid ocean water contact for at least three days after significant rainstorms.
The department says the runoff from the rain can end up in the ocean and it could carry bacteria, viruses and disease.
Health experts say this can cause skin, respiratory and intestinal problems.
The department says the elderly, children and people with compromised immune systems are especially prone to contracting these diseases.
People are advised to avoid ocean water during this time, especially close to creeks, rivers, storm drains and other runoff outlets that empty in the ocean.
For more information about beach water quality, please visit the Public Health Department Beach Water Quality website, or call the Ocean Water Monitoring Program Telephone Hotline at (805) 788-3411.