Summary
- New analysis by MethaneSAT team suggests oil and gas operators emitting at roughly 9% methane intensity relative to San Joaquin basin’s marketed gas production.
- Results come as state policymakers look to cut greenhouse emissions.
- MethaneSAT data goes beyond capabilities offered by other satellites or ground-based measurement tools, capturing basin-level emissions intensity and individual sub-basin hotspots.
Oil and gas operators in California’s San Joaquin basin are releasing 18 tonnes of methane emissions every hour, according to new analysis of MethaneSAT data. Based on observations collected in 2024 and 2025, MethaneSAT data analysis suggests the emissions are equal to approximately 9% of the region’s marketed gas production (although heavy crude oil is the industry’s main product in the area).
Located at the southern end of the state’s Central Valley, the basin is part of one of the world’s most productive agricultural regions. The oil and gas methane emissions as measured by MethaneSAT are roughly 20% higher than reported in the U.S. EPA’s inventory.
This high methane emissions intensity is significantly greater than the industry’s widely stated goal of reducing emission intensity down to 0.2% of marketed gas production by 2030. Since the basin produces large volumes of oil, we also estimate the total energy-normalized emissions intensity, which is 0.27 kg of methane per gigajoules of oil and gas production.
Methane is a potent greenhouse gas, with over 80 times the 20-year warming power of carbon dioxide.
The results are uniquely relevant to California policymakers currently working to reduce the state’s climate-warming emissions. Experts at Environmental Defense Fund believe the high emissions are the result of a regulatory loophole that unintentionally exempts more than 27,000 heavy oil wells from state emissions safeguards.
Those rules, adopted over a decade ago, are based on data collected in the 1990s, long before today’s methane measurement technologies existed. Since then, the California Air Resources Board has strongly embraced the latest monitoring tools, including Carbon Mapper and the California Methane Satellite Project.
Crucial insight
CARB takes a cutting-edge approach to addressing the largest leaks. The MethaneSAT data advances public understanding even further, thanks to its unique ability to quantify total emissions, including countless smaller sources dispersed over wide areas.
That insight is crucial. A recent study found that smaller sources (less than 100 kilograms per hour) dispersed over wider areas account for over 80% of total oil and gas methane emissions in the San Joaquin production basin. We believe the industry’s high emission rates relative to oil and gas output may also reflect the prevalence of fugitive emissions from low-producing oil wells in the region.
Based on the MethaneSAT data, total emissions from all sources in the area are two times higher than the gridded EPA inventory for the year 2020 (the most recent available). Emissions are quantified using a Bayesian atmospheric inversion framework, which generates a gridded emissions product at a resolution of 4 km x 4 km.
MethaneSAT’s unique capabilities make it possible to accurately quantify total emissions across the entire San Joaquin basin and other oil/gas basins worldwide. The combination of high-precision and high-resolution data across the entire basin provides new granular views of methane emissions from individual counties from the San Joaquin Basin, which was not possible with other satellite instruments.
Informing Policymakers
In May 2025, CARB presented a timeline for adopting a state plan for addressing oil and gas methane emissions consistent with the 2024 U.S. EPA methane rule, which would close the current loophole for heavy oil wells. But in November 2025, the Trump administration delayed state plan deadlines until January 2027. CARB will need to move forward this year to meet that deadline.
Data from MethaneSAT, Carbon Mapper and other methane measurement tools will be a critical resource as they do.
