Both methods are dependent on environmental and atmospheric conditions resulting in detection and quantication limits, see SI Section S-2. For example, methane in compressor driver exhaust (`methane slip') may be too dilute to be visible to Solution 1's imaging or emissions may pool or recirculate near large compressor buildings, possibly complicating or distorting either solution's quantication estimates. The controlled testing used single point sources in known locations that had less complex congurations than at midstream facilities, which have multiple, potentially overlapping and/or intermittent, emission sources and large structures that produce complex near-eld winds. Therefore, the uncertainty models used here should be considered minimum estimates of uncertainty; in eld conditions at complex midstream facilities, uncertainty is likely larger.