The stench of mass fish deaths in the Salton Sea have Los Angeles and large regions of southern California reeking of rotten eggs.

Residents across the Golden State were kicking up a stink after waking up to the foul odour, which has been compared to raw sewage, yesterday morning.

More than 200 residents clogged 911 lines with calls, prompting South Coast Air Quality Management District to send officials to investigate amid fears of a toxic spill or a waste plant leak.

Although there is still no official explanation of the smell, the prime suspect is the annual fish 'die-off' in the Salton Sea, which caused by low oxygen levels in the water and receding shorelines.

The area has long been plagued by mass fish deaths but this is the first time the stench has covered such a wide area.

The reason the smell is considerably worse this year than in previous years is thought to relate to local thunderstorms, 60 MPH winds and dust storms churning up the water.

The LA Times reported that officials from the Air Quality Management District and other agencies said they have never dealt with a stench quite like this.

“It's very unusual that any odour would be this widespread, from the Coachella to Los Angeles County,” said Sam Atwood, spokesman for the South Coast Air Quality Management District.

“We're talking well over 100 miles. I can't recall ever confirming an odour traveling that distance.”

The smell has led to widespread speculation on Twitter, with some even going as far as questioning their own personal hygiene when it became apparent they couldn’t escape the stench.

Jose Chavez - a 28-year-old comedian from San Fernando tweeted: "My first thought was that maybe one of the eggs I bought was rotted and I got back home and the smell was still there so then I started to think it was me so I changed my clothes...It was very pungent."