Report Finds MD’s Landfills Release 4 X More Methane and Carbon Dioxide Than State Estimates

Decaying Food and Municipal Waste Release as Much Greenhouse Gas Pollution as a Million Cars

BALTIMORE – A new report concludes that Maryland’s municipal waste landfills release four times more methane and carbon dioxide than the state’s previous estimates, contributing as much greenhouse gas pollution as almost a million cars driving for a year.

The Environmental Integrity Project’s report, “Greenhouse Gases from Maryland’s Landfills: Underestimated and Under Regulated,” is based on a review of state and federal records and data, with its numbers confirmed through collaboration with the Maryland Department of the Environment (MDE).

In total, decaying food, discarded consumer products, and other household waste in Maryland’s municipal waste landfills released about 51,500 tons of methane – a potent greenhouse gas – in 2017, the most recent year for which complete data were available, which was more than four times the 12,500 tons estimated by Maryland, according to EIP’s report.

In response to EIP’s report, MDE on June 9 released an updated greenhouse gas inventory for the state that said municipal waste landfills released about 58,000 tons of methane in 2017.

“This shows that Maryland really needs to do a better job of reducing, controlling and measuring greenhouse gases from landfills,” said Ryan Maher, Attorney for the Environmental Integrity Project (EIP) and lead author of the report. “We need to reduce our food waste, compost more, and impose strong new air-quality regulations that require improved methane controls systems at our state’s landfills.”

Over a 20-year period, each ton of methane released into the atmosphere has a global warming impact equivalent to about 86 tons of carbon dioxide, according to EPA and United Nation’s Intergovernmental Panel on Climate Change.

It is important to consider the global warming impact of methane over a 20-year timescale, instead of a longer timeframe like a century, because the consequences of climate change—including sea level rise, wildfires, and drought—are already causing significant harm in Maryland and around the world.

Using this time frame, the 51,500 tons of methane released in 2017 from Maryland’s 19 active municipal waste landfills and 21 closed landfills have as much global warming impact as 4.4 million tons of carbon dioxide, according to EIP’s analysis. The state’s landfills also emitted about 500,000 tons of carbon dioxide, including 64,000 tons from flares that burn waste gases.

Altogether, these 40 landfills released as much greenhouse gas pollution – the equivalent of 4.9 million tons of carbon dioxide — as about 975,000 passenger vehicles driving for one year, or four times the greenhouse gas emissions from the average Maryland coal-fired power plant. This makes landfills the largest source of methane in the state, not the natural gas industry as once thought.

To quantify the greenhouse gases emitted by Maryland’s municipal waste landfills, EIP reviewed MDE’s 2018 inventory of greenhouse gas emissions, which tabulated the state’s total greenhouse gas emissions for 2017.  EIP also examined federal data on Maryland’s landfills available through EPA’s Greenhouse Gas Reporting Program, as well as air quality reports that landfills submit to MDE each year.

The analysis revealed multiple calculation and data-based errors in MDE’s greenhouse gas inventory – including underestimating landfill gas production and excluding five landfills — that resulted in the sizeable underestimates of total landfill emissions. EIP met with MDE staff in April 2021 to discuss the report’s conclusions and MDE agreed that methane and carbon dioxide emissions from landfills are about four times higher than the official state estimates.  MDE updated its greenhouse gas inventory, in response to EIP’s report, on June 9.

The EIP report’s conclusions include the following:

  • Prince George’s County’s Brown Station Road Landfill emitted more greenhouse gases than any other Maryland landfill by far: 86,000 tons of carbon dioxide and 6,100 tons of methane. Washington County’s Forty West Landfill had the second highest greenhouse gas emissions, followed by Baltimore City’s Quarantine Road Landfill.
  • Contrary to the official state estimate, landfills are the leading source of methane in Maryland relative to other sectors, emitting 37 percent of the methane caused by human activities, rather than 13 percent. The natural gas industry was previously considered the leading source of methane in Maryland, but in reality it emits 17 percent of the state’s methane.
  • Maryland’s landfills had a greater climate impact than the state’s largest coal-fired power plant in 2019, Brandon Shores in Anne Arundel County. The landfills also emitted four times as much greenhouse gas as the average Maryland coal plant.
  • Only about half (21 of 40) of the landfills operate any kind of gas collection or control systems, and only four of these must comply with any government standards to ensure that they work.

The report recommends that Maryland take several steps to address the problem:

  1. MDE must issue strong new air quality regulations that require improved control and monitoring of greenhouse gases from the state’s landfills. Maryland’s rule should go well beyond the relatively weak requirements established by the EPA’s most recent set of regulations for landfills and should instead be modeled on stronger regulations issued in 2010 by California.
  2. MDE should complete a rulemaking process as quickly as possible and issue new landfill emissions regulations, which have been on hold since 2017. The state recently resumed this process – with a public meeting set for June 23 — and should complete it without any additional delay.
  3. Maryland should create financial incentives to spur on the construction of new facilities that can divert waste away from landfills and trash incinerators, which are also highly polluting. A 2021 law passed in Maryland requiring large generators of food waste to divert that waste away from landfills and incinerators will not be effective unless there are composting and organics diversion facilities that can accept the waste. Maryland must encourage the construction of such facilities and make information on existing incentives more readily available.
  4. County governments should assess the feasibility of operating county-run composting facilities. Thus far, there are only two publicly owned food composting facilities in Maryland, one in Howard County and one in Prince George’s County.
  5. Incinerating waste should not be treated as a solution to the findings discussed in this report. Trash incinerators emit very large amounts of toxic air pollution and carbon dioxide. Maryland also has a troubling history of siting or attempting to site these facilities in low-income neighborhoods and communities of color.
  6. To prevent underestimation of emissions from landfills in the future, Maryland and governments across the U.S. and globally should start relying on emissions monitoring and direct measurement instead of simply modeling, which caused problems in Maryland.

The Environmental Integrity Project is a 19-year-old nonprofit organization, based in Washington D.C. and Austin, TX, dedicated to enforcing environmental laws and strengthening policy to protect public health and the environment.

Media contact: Tom Pelton, Environmental Integrity Project, (443) 510-2574 or