Advances in Estimating Greenhouse Gas Emissions and Implementing Mitigation Strategies


For drinking water and wastewater utilities working to mitigate greenhouse gas (GHG) emissions, understanding current GHG emission sources is the first step. Utilities usually generate GHG inventories based on specific GHG inventory protocols or other guidelines. But when they perform such analyses, they often find that one of their most significant emission sources may also be the most difficult to accurately quantify: process emissions of methane. Methane is a potent GHG estimated to warm the Earth’s atmosphere 81–83 times as much as carbon dioxide over a 20-year period. An increasing percentage of methane emissions in the United States comes from wastewater treatment (e.g., from 10% in 1990 to 14% in 2019). However, there are limited measurements of methane emissions across the water sector, leading to large uncertainties in current GHG inventories.

This webcast covered the latest advances in estimating and monitoring direct methane emissions from wastewater utilities. Researchers from Princeton University will discuss recent studies that address this gap by providing the largest study of methane emissions from U.S. wastewater treatment and collection systems to date and their implications for the wastewater sector. Utilities and municipalities of all sizes will be able to apply the research results to enhance estimation and monitoring of GHG emissions to support utility climate action plans and mitigation efforts. In addition, the American Water Works Association and Water Utility Climate Alliance highlighted leading practices for implementing emission reduction strategies in the drinking water sector. Utilities looking for practical, on-the-ground examples of how to implement, finance, and scale-up GHG reduction projects will have the opportunity to learn from their water utility peers.


  • Mark Zondlo, PhD, Professor of Civil and Environmental Engineering, Princeton University
  • Jason Ren, PhD, Professor of Civil and Environmental Engineering, Princeton University
  • Emily Zegers, Senior Engineer, Process, Innovation & Energy, Toronto Water
  • Adam Carpenter, PhD, Manager of Energy and Environmental Policy, American Water Works Association


  • Harry Zhang, PhD, PE, Research Program Manager for Integrated Water and Stormwater, The Water Research Foundation