Jul 22, 2021

17 Million Gallons of Sewage Discharged From Hyperion Treatment Plant in Los Angeles

This sewage discharge closed some beaches to swimming.

sewage spill

Debris overwhelmed the Hyperion sewage treatment plant in Playa del Rey, Los Angeles, on July 18.

Officials were forced to use an emergency measure to discharge 17 million gallons of sewage through a pipe one mile offshore, reported The Los Angeles Times. The debris unexpectedly clogged filtering screens with openings less than an inch in size at the treatment plant, according to Barbara Romero, the director of L.A.'s Department of Sanitation and Environment.

The L.A. County Department of Public Health issued an advisory July 19, urging residents to avoid swimming in areas around Dockweiler State Beach and El Segundo Beach, reported The Los Angeles Times. Water quality samples were collected to look for elevated amounts of bacteria.

Screens were added to replace the ones that were blocked, but this was unsuccessful. Redirecting the flows to a storm drain system within the plant was another idea, but after a few hours the system was too overwhelmed.


According to Timeyin Dafeta, executive plant manager at the Hyperion Water Reclamation Plant, approximately 17 million gallons of sewage was discharged one mile offshore instead of the typical five miles to prevent the plant from discharging much more raw sewage, reported The Los Angeles Times. 

Dafeta believes that the incident was the largest amount of untreated sewage discharged through the one-mile pipe in the last 10 years. The cause of the debris is still being investigated, however.

By July 19, water flows were directed back through the normal treatment process and damaged equipment is in the process of being prepared.

“The flow wasn’t subsiding enough to get it through the treatment process,” Romero said, reported The Los Angeles Times. “Out of the 260 [million gallons] that comes in, we ended up with 17 [million] that couldn’t go through the treatment process.”

According to Dafeta, the amount of wastewater that had flowed into the ocean was mitigated because of improvements made after 2015, adding that “it’s the amount of material and the kind of materials that came through that caused the problem for the screens."

Read related content about debris & sewage treatment: