Bacteria levels exceeded California health standards at three Newport Beach beaches, the Newport Harbor Foundation reported Thursday, Oct. 1.

Sampling conducted by the Orange County Health Care Agency on Wednesday, Sept. 30, found elevated bacteria at 10th Street Beach, 15th Street Beach and Bayside Beach, according to the foundation's water quality alert on X. The foundation rated all three sites yellow on its color-coded map, meaning bacteria levels exceed state health standards and may cause illness.

The foundation monitors Newport Harbor water under the Surfrider Foundation's Blue Water Task Force program. Its tests measure enterococcus, a type of bacteria that signals fecal pollution from human or animal waste.

California's single-sample limit for saltwater beaches is 104 colony-forming units of enterococci per 100 milliliters of water, according to the California State Water Resources Control Board. The foundation's alert did not include exact bacteria counts for the three sites.

Swimming, surfing or wading in water with elevated bacteria can cause fever, vomiting, and throat and eye infections, the state water board says.

Bayside Beach has been flagged before. The foundation issued a similar alert on July 30 after July 29 sampling found bacteria above safe levels at Bayside Beach and 33rd Street Channel. The Sept. 23 sampling round flagged a different location, Lido Isle Yacht Club Beach.

The OC Health Care Agency's beach status website showed no active closures, warnings or advisories as of Oct. 1. The gap between the foundation's alert and the county's official postings may reflect a lag in processing raw sampling results, or differences in how harbor and bay sites are tracked compared with ocean beaches.

The OC Health Care Agency's Water Quality Laboratory, based at Shellmaker Island in Newport Beach, tests up to 150 shoreline sites across 25 Orange County beaches each week. State law requires weekly testing at high-use public beaches near storm drains from April through October.

Residents can check current beach conditions at ocbeachinfo.com or call the OC Health hotline at (714) 433-6400.