Methane is a potent greenhouse gas that significantly contributes to climate change. While we often think of oil and gas operations, landfills, and dairy farms as main sources, there’s another player: reservoirs. As plants decay underwater, they release methane, which escapes into the atmosphere. Surprisingly, California isn’t currently monitoring these emissions, but environmental groups are calling for action.
John Harrison, a professor at Washington State University, emphasizes the importance of tracking methane emissions from reservoirs. “They constitute a significant source,” he says. Understanding this could improve California’s energy policies and bolster its climate leadership.
A coalition of environmental organizations, such as Friends of the River and Tell The Dam Truth, recently filed a petition urging the California Air Resources Board to require better reporting of greenhouse gases from reservoirs. Their concerns are shared by many, as California aims to cut methane emissions by 40% compared to 2013 levels by 2030.
Keiko Mertz, policy director at Friends of the River, calls methane emissions from reservoirs a “blind spot.” She points out that such a significant greenhouse gas needs to be accounted for. As debates continue over projects like the proposed Sites Reservoir, emission estimates have become a contentious issue.
Measuring methane from reservoirs isn’t easy. Scientists say it can spread out and be difficult for satellites to detect. However, advancements are on the way. Riley Duren from Carbon Mapper states that more sensitive tools are being developed, which could provide better detection within the next couple of years.
The U.S. Environmental Protection Agency (EPA) highlighted that flooded lands, including reservoirs, are major methane sources. They estimate that emissions from these areas could be equivalent to 44.4 million metric tons of carbon dioxide annually—comparable to emissions from U.S. steel and iron plants.
Research indicates that global dam emissions range between 10 and 22 million metric tons of methane each year, accounting for 3% to 7% of all human-caused methane emissions. Understanding how much each reservoir contributes is crucial, especially as new hydropower plants are built.
Studies show that some hydropower facilities can emit considerable greenhouse gases, sometimes even more than coal plants for the amount of energy produced. Given that about 3,700 new hydroelectric facilities are planned globally, a close examination of their climate impact is essential. “Hydropower is not carbon-free,” says Steven Hamburg, chief scientist at EDF. He stresses the need to minimize emissions when building new plants.
The ongoing discussions about methane emissions from reservoirs have caught attention on social media and among climate advocates. Many users are sharing insights about the need for better regulation and tighter emissions standards. This growing awareness reflects a shift in how we view the very systems we rely on for energy.
The California Air Resources Board will respond to the petition soon. In developing its data, the agency considers guidelines from the U.N. Intergovernmental Panel on Climate Change, which provides methods for estimating methane emissions from various sources, including reservoirs.
Overall, addressing methane emissions from reservoirs presents an opportunity to enhance California’s climate policy. Better data could lead to smarter energy management and a clearer understanding of the true environmental cost of hydropower.
