The Environmental Integrity Project’s examination of state and federal data reveals that Maryland’s municipal waste landfills release far more greenhouse gases than was previously thought, making these landfills the single largest source of methane pollution in Maryland, even larger than the natural gas industry. In total, Maryland’s municipal waste landfills released about 51,500 tons of methane in 2017, the most recent year for which comprehensive data are available. That was four times greater than the Maryland Department of the Environment’s official state estimate of 12,500 tons.