UPDATE | Investigators looking into the source of a foul odor originating from the Dominguez Channel in Carson have now said that it’s due to a leaking pipeline and not organic material that was exposed by low tides as previously reported, Carson Mayor Lula Davis-Holmes said Friday.

Davis-Holmes issued an update Friday afternoon saying that investigators from Los Angeles County and the South Coast Air Quality Management District found a pipeline leaking hydrogen sulfide near the Avalon exit of the 405 Freeway. However, the South Coast AQMD had not confirmed any leaking pipe or source.

Hydrogen sulfide is used for a number of purposes including oil and gas refining. The Avalon exit is just a few miles up the Dominguez Channel from the Marathon Refinery in Carson.

The effects tied to prolonged exposure to hydrogen sulfide depend on the concentration of the gas but can range from nausea and headaches, fatigue, respiratory tract irritation and can lead to death in high-concentration settings.

Davis-Holmes said she has called for a full investigation and criticized the lack of information released prior to Friday.

“My question now to all involved agencies is now that we have identified the problems what and when will the problem be corrected. Who is at fault and what will be done to prevent this from happening again,” Davis-Holmes wrote on her Facebook page. “This lack of transparency is unacceptable.”

A statement from the city of Carson Thursday night said that investigators had tied the foul odor to organic material being exposed due to low tides and said that there were no anticipated health effects other than the nuisance of the smell.

Davis-Holmes advised residents to avoid the area because hazmat crews and other agencies would be on site for several days. She encouraged residents to contact her office or the AQMD if the odor persists or gets worse.

PREVIOUSLY: What’s that horrible smell in Long Beach? It’s from the Dominguez Channel, officials say

10/8/2021 at 1:23 p.m. | The origin of a foul stench that has been hanging over some Long Beach communities since at least Wednesday has been tracked to organic material drying out in the Dominguez Channel after low tide, according to a statement from the city of Carson.

The Dominguez Channel runs through Carson before turning south and running near the western edge of Long Beach’s city limits and emptying into the waters north of the ports of Los Angeles and Long Beach.

A map showing the route of the Dominguez Channel in relation to Long Beach. Illustration by Candice Wong.

Residents in neighborhoods spanning from North Long Beach to the Peninsula have complained of a nauseating smell that they compared to sulfur.

Speculation about its source spread on social media ranged from people questioning if it was a leak at a refinery to wondering if the stench was emanating from the oil spill that happened over the weekend off the coast of Huntington Beach.

The South Coast Air Quality Management District said it was investigating the ongoing odor issue Thursday and the city of Carson issued a statement late Thursday saying that Los Angeles County Public Works and Public Health had preliminary findings that the smell was due to organic material.

But Carson Mayor Lula Davis-Holmes is still seeking an official answer and said a lawsuit could be in line depending on the official source of the smell.

“The odor being smelled is believed to be H2S, Hydrogen Sulfide,” Davis-Holmes said in a statement. “It is my understanding that prolonged exposure is harmful to humans.

“I am therefore calling for an investigation and depending upon the results of this investigation and the negative impacts to my residents; the City might consider initiating a class action lawsuit similar to what happened in Porter Ranch. I’m hoping that expected rain in the forecast tonight will wash away the organic material and reduce or improve the odor situation.”

Davis-Holmes also asked what was being done to correct the issue so that residents don’t have to smell these kinds of odors in the future.

The statement from Carson said that AQMD investigators have eliminated tank farms, oil refineries and waste treatment facilities as the source of the smell. The AQMD believes the smell will not cause any health impacts other than “nuisance type effects.”

A spokesperson for the SCAQMD could not be immediately reached.

Editor’s note: The latest version of this story was updated with an additional statement that the South Coast Air Quality Management District did not confirm any leaking pipe or source.

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Jason Ruiz covers City Hall and politics for the Long Beach Post. Reach him at [email protected] or @JasonRuiz_LB on Twitter.