By Al Sattler, Group Vice Chair

Photo of Dominguez Channel by L.A. Sanitation

In early October, residents of Carson started smelling a stink, the “rotten egg” smell of hydrogen sulfide. The stink was intermittently detectable in much of the South Bay, but it was unbearable in Carson. The South Coast Air Quality Management District (SCAQMD), which was called to investigate, put a large number of inspectors into the area looking for likely industrial sources of hydrogen sulfide, with refineries being the usual suspects. No industrial culprits were found. Eventually it was decided that it was coming from biological activity in the Dominguez Channel, which is effectively a huge storm drain that receives runoff water from as far north as the 105 Freeway, draining several South Bay cities, including Hawthorne, Gardena, and Carson, and carries it to LA Harbor.  There is always water in it, rising and falling with the tides. With the drought, however, there has been no flow through it, so it is essentially a stagnant body of water.

When certain bacteria grow without oxygen, they can naturally produce hydrogen sulfide. L.A. County pumped oxygen into the bottom of the channel, and the odor eventually faded away. But it took weeks!

In the meantime, residents of Carson were suffering. Despite claims that there should be no long-term health effects from this concentration of hydrogen sulfide, people were having headaches, breathing discomfort, nausea, and even vomiting. People were advised not to exercise at night when it was worst. 

You can smell hydrogen sulfide when there are 0.5 parts per billion (ppb) in the air, a much lower concentration than the Cal-OSHA occupational safety limit of 10,000 ppb.  At two community air monitoring stations in Carson, concentrations almost 1000 ppb were measured. The SCAQMD measured up to 7000 ppb immediately next to the Dominguez Channel. 

Los Angeles County paid for 27,000 air purifiers for residents, and reimbursed over 3,000 people for their stay in hotels to escape from the smell.

The deadline to submit receipts and documentation for reimbursement has been extended to Friday, Dec. 31, 2021, at 11:59 p.m. https://lacounty.gov/emergency/dominguez-channel/

There has probably never before been a massive stink from the Dominguez Channel like this. Something must have activated the bacteria in the stagnant bottom of the channel, perhaps by feeding them more nutrients. Acidifying the water, which would drive more hydrogen sulfide out, is another possibility.  The most obvious culprit is the company that had a massive warehouse fire on September 30, with runoff water from fighting the fire presumably flowing into storm drains and thence into the Dominguez Channel. The only publicly stated chemical rinsed down was ethanol perhaps from hand sanitizer. However, there were undoubtedly other chemicals. 

On December 3, the AQMD issued notices of violation to Virgin Scent, dba Art Naturals and Day to Day Imports, Inc., Liberty Properties, Prologis, and LA County.

Information on air monitoring by the AQMD is at https://www.aqmd.gov/home/news-events/community-investigations/dominguez-channel.

Community air monitor informaton: https://xappprod.aqmd.gov/Rule1180CommunityAirMonitoring/

(More about that in the Mar/Apr issue.)

LA County:  https://lacounty.gov/emergency/dominguez-channel/