The studies in the review generally indicate that wastewater collection and treatment do not dominate U.S. and Canadian cities' emissions profiles. For example, quantified CH4 emissions from 63 WWTPs across the U.S. mid-Atlantic and California using a vehicle-based system and integrated Gaussian plume modeling combined with Bayesian inference. The mean TD rate derived from the estimates in the study was 28.4 kg CH4/h, which is about 34 times lower than the mean CH4 pointsource emissions rate from 96 U.S. landfills quantified in . estimated that WWTPs are responsible for 6% of total CH4 emissions in aggregate in SFBA, and estimated that the Rumpke Landfill in Cincinnati emitted 37 million times more CH4 in 2015 than all 84,000 manholes and sewer grates in the city. These examples illustrate that CH4 emissions from wastewater collection and treatment in U.S. and Canadian cities may be small compared to other sources.