Los Angeles County beaches are some of the most recognizable and popular in the world, stretching nearly 25 miles from Nicholas Canyon in Malibu to White Point/Royal Palms in San Pedro. Each year, they attract more than 50 million visitors, tourists and locals alike. Unfortunately, many in 2023 have experienced high levels of bacteria and other contaminants. Polluted waters pose a significant health risk to both people and ocean-dwelling creatures. People coming into contact with such water are more likely to contract illnesses including stomach flu, ear infections, upper respiratory infections, and rashes. Recent media reports have shown beached seals lying dead on the region’s sandy shores.

The L.A. County Department of Public Health releases a list of areas to avoid swimming, surfing, and playing in ocean waters. One recent list included 11 locations along its coast, including two swimming areas at Redondo Beach and one each at Hermosa Beach, Palos Verdes Beach, Manhattan Beach, Carbon Canyon Beach in Malibu, Malibu Pier and Beach, Malibu Lagoon State Beach at Surfrider Beach, Bluff Cove at Palos Verdes Beach, Inner Cabrillo Beach in San Pedro, and Santa Monica Pier and Beach—in other words, nearly the entire L.A. County beach coastline.

Officials measure bacteria levels by sampling types of fecal-indicator bacteria (FIB), including total coliform, fecal coliform, and Enterococcus spp. The amount of fecal-indicator bacteria present in runoff, and consequently present at the beach, is currently the best indication of whether a beach is safe for recreational water contact. Though fecal-indicator bacteria themselves do not usually cause bather illness, their presence is a sign of potential contamination by other pathogenic microorganisms, including viruses, protozoa, and other types of bacteria—all of which do pose health risks to humans. And when FIB levels are high, other contaminants, including toxic heavy metals and pesticides, are often present as well.