Porter Ranch Methane Leak Declared Largest Ever In U.S. History – Over 100,000 Tons Of Natural Gas Equivalent To Pollution From 600,000 Cars

The methane leak at Porter Ranch in Los Angeles has been declared as the largest known accidental release of natural gas in U.S. history.

The methane gas leak near Porter Ranch, California, has been one of the largest environmental disasters in U.S. history. At its peak, the nearly four-month leak released close to 100,000 tons of methane. That is equivalent to the annual pollution of about 600,000 cars plying on America’s roads. The leak effectively doubled the methane emissions rate of the entire Los Angeles Basin and forced thousands of Los Angeles residents from their homes. Scientists observing the leak have affirmed that the incident is the largest known accidental methane release in U.S. history.


The leak released 97,100 metric tons or 5 billion cubic feet (142 million cubic meters) of methane over 112 days, reported Gizmodo. According to the scientific paper published in Science, that’s equivalent to annual greenhouse gas emissions of over half a million cars. Speaking about the calamity, Don Blake, an atmospheric scientist at UC Irvine and a co-author on the Porter Ranch gas leak study said the following.

“This is by far the biggest [methane leak] I’ve ever seen.”

Attesting to the findings, co-lead author Stephen Conley of UC Davis and Scientific Aviation added to the statement.

“Aliso Canyon will be, certainly, the biggest single source of the year. It’s definitely a monster.”

Conley was referring to the location where the methane leak occurred. Large quantities of methane gas started leaking at an underground natural gas storage facility in Aliso Canyon in Porter Ranch. It was first detected Southern California Gas Co. on Oct. 23. Though invisible to the naked eye, thick invisible plumes of methane had been invading homes in the Porter Ranch area. Since the gas is odorless, it was difficult for residents to identify the cause of their headaches and nausea. However, soon the reason became known and mild panic ensued. Methane isn’t toxic, but it can cause difficulty in breathing.


Horrifyingly, the California Air Resources Board says it was not notified of the leak by the company until Nov. 5, reported Los Angeles Times. It was merely by chance that Conley, who had been working with the California Energy Commission, stumbled upon the methane leak in Porter Ranch. While working on a project to look for pipeline gas leaks in November, he was asked to visit Los Angeles to study the gas that had been spewing from the failed Aliso Canyon well,

“This was just a fortuitous event, that the California Energy Commission realized the importance of the Aliso Canyon situation.”

After Conley flew a single engine plane rigged with sensors that picked up concentration of methane and ethane, two of the most common inflammable natural gasses, he became acutely aware of the enormity of the problem. The leak not only made many people sick, but eventually forced the temporary relocation of more than 6,600 households from the northern Los Angeles community of Porter Ranch at the edge of the gas field, reported Yahoo.


The report merely confirmed the suspicions about the enormity of the methane leak. However, more importantly, the leak has proven just how poorly equipped the disaster management team is in scientifically responding to such disasters. The leak has stressed the urgent need to formulate procedures that offer a rapid scientific response in case such a calamity strikes again.

Methane is a far more potent greenhouse agent. While it is an excellent component in natural gas owing to his high calorific content, it is far more destructive than carbon dioxide to the environment. Methane continues to linger in the atmosphere for almost a decade, trapping sunlight and raising temperature. The methane leak in Porter Ranch is roughly equivalent to annual energy-sector methane emissions of a medium-sized European Union country, noted the report.

[Photo by Frederic J. Brown/Getty Images]