Since these three plumes represented ≈15% of all emissions estimated by aircraft for this study, uncertainty about cause and estimated rate is material to basin-scale emission estimates derived from aircraft plume estimates. More broadly, most aerial studies do not have the complete facility list utilized here and therefore would struggle identifying plumes unattached to a likely emitter; no such analysis was conducted in any study known to the authors. This type of plume classication therefore represents an uncertainty of unknown size in emission studies using plume estimates.