Updated at 8:05 p.m. Sept. 10:
The following is an emailed statement from the South Coast Air Quality Management District (AQMD) regarding a foul odor permeating much of Southern Callifornia Monday:
Air quality officials are continuing to investigate the source of a rotten-egg odor reported last night and today across much of Southern California, from the Salton Sea to the San Fernando Valley.
“Several factors indicate that the Salton Sea may have been the source of these odors,” said Barry Wallerstein, executive officer for the South Coast Air Quality Management District (AQMD). “However we do not have any definitive evidence to pinpoint the Salton Sea or any other source yet.”
AQMD deployed field inspectors today to the San Fernando Valley, Long Beach, Colton, San Bernardino, Riverside, Perris, Temecula, Banning, Palm Springs, La Quinta and the Salton Sea in an attempt to locate the source of the odor.
Several sources have reported hot weather and a possible release of bacteria from the bottom of the sea due to winds there. Those conditions could cause strong sulfur odors.
In addition, strong thunderstorm activity in the Salton Sea area and resulting high winds from the southeast could have pushed odors into the Los Angeles basin. However, it is highly unusual for odors to remain strong up to 150 miles from their source, Wallerstein said.
AQMD will collect air samples this evening in several locations throughout the Coachella Valley and at the Salton Sea. An analysis of those samples may provide further evidence of a possible source.
Since midnight last night, AQMD has received about 200 complaints of sulfur- and rotten-egg odors. Most callers were from the Coachella Valley and other portions of Riverside County as well as San Bernardino and Los Angeles counties. Only a few calls came from Orange County.
A strengthening onshore breeze tomorrow may keep any additional odors from spreading as far west as they did today, AQMD officials said.
AQMD is the air pollution control agency for Orange County and major portions of Los Angeles, San Bernardino and Riverside counties.
The South Coast Air Quality Management District (AQMD) is investigating a sulphuric odor—described by residents across Southern California as a "rotten egg" smell—according to an emailed statement.
AQMD, which monitors pollution levels in the region, released a statement Monday saying the agency's inspectors were attempting to track the origin of the malodor, following more than 100 calls about it.
"Residents have complained from a very wide area including the Inland Empire and much of the Los Angeles Basin,'' according to an AQMD statement.
"Fish kills, algae blooms and other biologic conditions in lakes can cause strong odors. Industrial facilities such as wastewater plants also can cause sulfur odors. At this time, AQMD hasn't confirmed any source as the cause of the widespread odor."
Residents in French Valley, Temecula and Murrieta were among those who reported the odor, which was described as a "rotten egg smell."
Weather and utility officials said the smell plaguing southwest Riverside County on Monday morning was most likely attributed to the Salton Sea.
"There is a smell that is coming off of the Salton Sea that because of our current weather conditions is bringing that smell to the area," said Randon Lane, spokesperson for Southern California Gas Co.
Lane said gas company officials have had numerous reports of the smell throughout Riverside County, but thus far had not found any gas leaks associated with the smell.
"As we get the calls we will continue to send people out," Lane said.
The Murrieta Police Department is fielding some calls about the odor, as well, according to Lt. Rob Firmes.
He also attributed it to the weather conditions, saying that according to weather officials, humidity was not allowing normal odors to properly escape the ground.
Murrieta was due for possible thunderstorms and showers throughout the day, according to the National Weather Service.
"The smell is from the Salton Sea," said Senior Meteorologist Kevin Martin with Southern California Weather Authority.com. "An outflow boundary came in last night from Yuma, Ariz., ... crossed the Salton Sea and carried the smell up the Coachella Valley and through the Banning Pass, which ejected outward into the Inland Empire, Orange and Los Angeles County areas."
The Salton Sea is located about 30 miles south of Indio in Riverside County.
Officials at the Eastern Municipal Water District, which services customers from Moreno Valley to Temecula, said the stench was not connected to any of the district's operations.
The EMWD directed further inquiries to AQMD.
Riverside County fire officials expressed no need to "dial 911 to report the odor."
"An unusual odor (rotten egg-like), has been reported throughout Riverside County and also reported as far west as Los Angeles County and has been noticable since early this morning," wrote Jody Hagemann, a spokesperson for CAL FIRE/Riverside County Fire Department.
"The Air Quality Management District is aware of the odor and is investigating and also states they are not aware of any specific hazards associated with the odor," according to Hagemann.
—City News Service contributed to this report.