Rancho Cucamonga Natural Gas Leak

Updated: August 16, 2017


A natural gas leak on Jadeite Avenue in Rancho Cucamonga was reported to Southern California Gas Co. by local residents on May 8, 2017. SoCalGas stated that they had found the leak, repaired it, and are pumping out gas that leaked into the soil for an unknown length of time.

The SCAQMD was informed of the incident on May 18, 2017. Inspectors were dispatched the same day, and took readings with field instruments as well as one air sample. Some of the field measurements collected inches above the ground or at holes punched in the sidewalk found very high levels of methane (approximately 10% or higher), and SCAQMD staff notified the Rancho Cucamonga Fire Department of these findings. Methane measurements collected a few feet above the ground were significantly lower than where these very high levels were detected.

SCAQMD inspectors and air monitoring staff returned the following day and have been there  almost every day since May 18th  to further assess air quality in the area. Staff has talked with the City of Rancho Cucamonga regarding inspection activities.

SCAQMD is continuing to assess this situation. This page will be updated as further information becomes available.

Information About Methane

Methane is the main component of natural gas. Methane is a colorless and odorless gas, and it is flammable in high concentrations, between 5% and 15% (equivalent to 50,000 to 150,000 ppm). Methane is considered to be biologically inert, but can cause health effects when levels are high enough to displace oxygen in the air, which can pose a suffocation hazard. However, this is generally only a concern in confined spaces (such as the inside of a tank), rather than in outdoor environments or typical indoor environments, where oxygen is readily available. Methane is not considered an air toxic, as it is not on the California Toxic Air Contaminants list, nor the California Proposition 65 list, nor is it on the U.S. EPA Hazardous Air Pollutants list.  However, methane is considered a climate pollutant (i.e. greenhouse gas), and is primarily regulated through state and federal regulations.

Air Monitoring Overview & Results

Air Quality Complaints

Members of the public within SCAQMD's four-county jurisdiction (Orange County and urban portions of Los Angeles, Riverside, and San Bernardino Counties) are encouraged to report air quality problems they observe to 1-800-CUT-SMOG (1-800-288-7664) or via SCAQMD's online complaint report form.

Please also contact SoCalGas at 1-800-427-2200 if you believe you are smelling a natural gas leak (rotten egg odor) and you live in a SoCalGas service area.