Several Los Angeles-area beaches were closed Monday to swimmers and surfers after 17 million gallons of sewage spilled into Santa Monica Bay from a treatment plant.

Los Angeles County Supervisor Janice Hahn said on Twitter that an unspecified mechanical failure caused the spill Sunday at the Hyperion Water Reclamation Plant.

Katherine Pease, Director of Science and Policy at Heal the Bay, said the spill is an environmental hazard.

“Given the scale and that it was raw sewage, I am worried about the public health impact,” she said.

About four miles of beaches from El Segundo to the southern end of Playa del Rey were closed indefinitely while officials conducted tests on the water. Impacted beaches include:

  • Beach # 110 – Dockweiler State Beach at Water Way Extension
  • Beach # 111 – Dockweiler State Beach at Hyperion Plant
  • Beach # 112 A – El Segundo Beach
  • Beach # 112 B – Grand Ave. Storm Drain

Public Health officials are advising residents to avoid contact with ocean water in the affected areas. Water quality samples are being collected by Public Health and LA City (Hyperion) staff.  The affected beaches remain closed until water samples are confirmed negative for elevated bacteria. The testing results are expected to be available within 24 hours. Beach users are advised to stay out of the water until the advisory is removed.

Pease said there are more rapid tests widely available and County officials need to explain why the 24-hour test is the only one being used at this time. She said locals should consider a wider area off-limits for the short term until test results are available.

“We are encouraging folks to stay out of the Santa Monica Bay right now,” she said.

Hyperion Executive Plant Manager Timeyin Dafeta said in a statement that the facility “became inundated with overwhelming quantities of debris, causing backup of the headworks facilities.”

“The plant’s relief system was triggered and sewage flows were controlled through use of the plant’s one-mile outfall and discharge of untreated sewage into Santa Monica Bay,” Dafeta said.

About 6% of the facility’s daily load was discharged through pipes that extend 1 mile and 5 miles offshore as an emergency measure to prevent the plant from going offline and spewing even more raw sewage, the statement said.

Pease said one silver lining was that most of the solid matter in the waste appears to have been filtered before hitting the ocean. However, more sewage appears to have used the shorter pipe meaning the impacts will be closer to beaches. She said the impact to wildlife may be limited in the long term as the sewage will dissipate but algae blooms are possible after an event like this and those blooms can themselves be toxic to wildlife.

She said incidents like this should remind everyone that water quality can vary and pollution levels should be checked before visiting local beaches using a service like Heal The Bay’s report cards (https://healthebay.org/wp-content/uploads/2021/06/Beach-Report-Card-2020-2021.pdf).