An additional third of proposed matches were due to data omitted from Stage 1 reports for a variety of reasons (see SI). Each of these was assigned a probability depending upon how well the explanation matched observed plume location and behavior. The third category, Timing, were due to relatively small dierences between reported time and aircraft overight times. Due to delays in acquiring CDPHE data to nalize the facility list, Stage 2 matching was performed on a partial facility list, and these 11 plumes were later matched to the improved facility list in June 2023, illustrating the importance of a complete facility list for this type of analysis. To minimize possible conrmation bias, Stage 2 matching was not repeated with these plumes. Lack of analysis for these plumes indicates that some valid plume-event matches may have been omitted from the totals.