County officials said Thursday night that they will begin treating the water from the foul-smelling Dominguez Channel starting as soon as today.

Mark Pestrella, the director of the county’s Department of Public Works, said during a special meeting of the Carson City Council that his department will begin spraying a citrusy, biodegradable organic matter on top of the water. The spray, he said, has been used to treat sewage water, according to his research.

Hydrogen sulfide has been a by-product of the decay and decomposition of vegetation within the channel, and the spray will convert the hydrogen sulfide into salt, which will then sink to the bed of the channel, Pestrella said.

“The residents of Carson should see a noticeable difference in the odor,” he said. Residents should be seeing results in three to five days, he added.

The county will also be using mechanical bubblers to aerate the water, which will counter the by-production of hydrogen sulfide. They plan to air out the water on Monday, he said.

Officials from the county’s public works department, fire department, District Attorney’s office, state Fish and Wildlife office and the state Water Resources Control Board have all been investigating the foul odor, Pestrella said. They believe the cause of the smell is due to an “illicit discharge” of materials into the water, including cardboard, pallet pieces and ethanol, he said.

The Dominguez Channel near the 405 Freeway exit on South Avalon Boulevard and East Dominguez Street on Thursday, Oct. 14, 2021. Photo by Crystal Niebla.

The channel had a “humongous boost” in decay due to this illicit discharge that happened upstream in the channel because organisms began feeding the materials, such as the cardboard, he said.

As the organisms fed off the cardboard, they created hydrogen sulfide as a byproduct.

“This is probably what boosted this smell,” he said.

The vegetation in the channel regularly decays then dies off throughout the season depending on the season, temperature and rain.

“We treated it first as a regular scenario, but as we became more aware of the persistence and strength of the smell, we knew we had something different going on,” Pestrella said.

The agencies suspect the discharge of cardboard came from a large pallet fire that took place upstream two weeks ago. A criminal investigation might be underway, Pestrella said, but it wasn’t clear whether that investigation had to do with the fire or the materials found in the channel. Pestrella said he could not provide more details.

The county has also decided that the channel will need to be recharged by removing the water and vegetation, and implement an “environmental restoration project” for the channel, Pestrella said. At this time, the timeline of the restoration is unclear.

Reimbursement and relocation updates

Since the last Carson City Council meeting on Monday, the county public works department implemented the following updates and specifications on its reimbursement program, which is intended for those who are seeking financial assistance for this foul odor event:

  • The county can reimburse up to $60 per unit per household for purchasing air filter inserts with HEPA-activated carbon for heating, ventilating and air conditioning systems. (In other words, if you own two HVACs, they can reimburse you $120 for the cost of the filters.)
  • The county can reimburse up to $400 for households 1,000 square feet or smaller and $800 for homes above 1,000 square feet.
  • The county can reimburse up to $182 per day for a hotel stay within the county; meals and groceries will be reimbursed at up to $66 per day for each person that is currently residing in the household that this being relocated.

Hospital fees and increased electricity bills related to the foul odor could also be reimbursed, Pestrella said. All reimbursement claims will be evaluated on a case-by-case basis, he said.

Receipts, except for meals, are required for all reimbursements within 14 days of the reimbursement request, and the county will reimburse the applicants within 21 days from the date of receiving the receipt(s).

LA County residents outside of Carson, such as those living in Long Beach, Wilmington and Gardena, may also apply for the county’s reimbursement program.

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

The public works department is also now recommending that residents call 211 instead of public works because the 211 call center has a higher capacity to take calls and connect local residents to the reimbursement program.

Carson councilmembers raised concerns over the accommodations given to nearby residents being negatively affected by the foul odor.

Carson Mayor Lula Davis-Holmes said the space for hotels isn’t enough for larger families and may need higher-priced hotels.

“I cannot put five people into one bed,” Davis-Holmes said.

Thursday’s special meeting came after a rally outside of Carson City Council, where about 30 local residents said the odor has been unbearable and demanded stronger actions from the city. Exposure to hydrogen sulfide has caused people symptoms including headaches, eye, nose and throat irritation, sneezing, dizziness, insomnia, nausea and even vomiting, they said.

Those in need of assistance, call 211 or visit

Long Beach to ask for federal, state help with foul odor from Dominguez Channel