Rotten Egg Smell Caused By Salton Sea, Officials Confirm

The Salton Sea is the likely source of

“We now have solid evidence that clearly points to the Salton Sea as the source of a very large and unusual odor event,” Barry Wallerstein, executive officer of the South Coast Air Quality Management District, said Tuesday.

The agency reported that since the early morning hours of Monday, AQMD received about 235 complaints of sulfur- and rotten-egg type odors.

“Almost all calls were received by 5:30 p.m. on Monday, with only a dozen or so received overnight and Tuesday morning,” according to an AQMD statement.

Tuesday's AQMD statement said a strong thunderstorm and 50 mph winds out the southeast that developed over the Salton Sea Sunday evening pushed odors to the northwest -– across the Coachella Valley, through the Banning Pass and across the Los Angeles Basin. Since Monday, an onshore breeze from the west appears to have kept the odor at bay, according to the agency's statement.

AQMD technicians took numerous air samples in Riverside and San Bernardino counties Monday, while AQMD field inspectors conducted odor surveillance in the Coachella Valley and across the agency’s four-county jurisdiction, the statement read.

Tuesday’s analysis of the air samples “showed a clear progression of hydrogen sulfide levels, with the highest concentrations found at the Salton Sea and decreasing concentrations found as the distance increased from the sea,” the statement read.

Hydrogen sulfide, a product of organic decay -- such as that occurring in the Salton Sea -- has an unmistakable rotten-egg odor, according to the agency.

The progression, or gradient, points to the Salton Sea as the source of the odor, Wallerstein said.

AQMD inspectors visited other potential odor sources, such as landfills and oil refineries, but ruled them out.

Scientists theorized that strong winds pushed surface waters aside and allowed water from the bottom of the shallow sea -- rich with decaying and odorous bacteria -- to rise to the surface, the statement read.

While hydrogen sulfide concentrations at the Salton Sea Monday were higher than normal, they were not high enough to cause irreversible harm to human health, AQMD officials said.