Long Beach’s beaches and swimming areas remained temporarily closed on Monday after more than eight million gallons of raw sewage spilled into the Dominguez Channel waterway in Carson last week.

The spill was reported on Thursday night when a 48-inch sewer mainline at 212th Street and Moneta Avenue failed during a rainstorm, leaking sewage into the waterway that empties into Los Angeles Harbor.

Bryan Langpap, a spokesman for the Los Angeles County Sanitation Districts, said the spill, estimated to at 8.5 million gallons, is the largest since the agency began tracking such incidents in 1981.

The flow was stopped around 9 a.m. on Friday and has not reoccurred, said Langpap, adding that crews are now working to repair the line and determine the cause.

The incident prompted the Long Beach Health Department to temporarily close swimming areas along the city’s 7 miles of beaches due to elevated bacterial levels.

Long Beach Health Department spokesperson Jennifer Rice Epstein said the city was taking water samples on Monday morning and will need two good results in a row before beaches can reopen.

Click here for an update on city beach closures.

Los Angeles County Supervisor Janice Hahn has called for an investigation into the cause and whether aging infrastructure possibly played a role.

“A sewage spill of this magnitude is dangerous and unacceptable and we need to understand what happened,” Hahn said in a statement Friday. “The recent storm undoubtedly contributed to the spill but we need infrastructure that doesn’t fail when it rains.”

Langpap said the concrete sewer pipe was built in 1961 and was set to be replaced in less than a year.

The Dominguez Channel has seen a wave problems in recent months. In October, thousands of mostly Carson residents were temporarily relocated due to hydrogen sulfide gas.

The stench was caused by decaying organic material in the channel from a warehouse fire that leaked hand sanitizer and other ethanol-containing products into the channel, promoting the South Coast Air Quality Management District to issue violation notices to Los Angeles County and four companies.

Langpap on Monday said the South Coast Air Quality Management District tested two monitoring stations in the area on the night of the sewage spill and detected no hydrogen sulfide.

He said the agency tested the area again on Sunday and found no elevated levels.

“At this time we’re feeling pretty good that there’s no hydrogen sulfide, so this isn’t going to contribute to what the poor people of Carson have already had to deal with,” he said.