As noted earlier, midstream facilities often include equipment with signicant combusted and/or vented emissions, including combustion slip from compressor drivers and gas upgrading equipment, and venting from centrifugal compressor seals and reciprocating compressor rod packing when those units are pressurized. All above sources tend to be concentrated near compressor units or upgrading equipment, which in the DJ basin are typically housed in large buildings that disturb winds and may cause pooling of emissions. Major equipment on midstream facilities operates most of the time (Figures S-11 to S-13); many large units operate more than 95% of the time, and few midstream facilities have long periods with no compression or processing in operation. Therefore, on these facilities, the emissions should be detectable by aircraft on nearly all overights, or, alternatively, may be too diuse and seldom/never detected. In the latter case, aircraft estimates would be lacking and would need to be replaced using non-aircraft estimates to calculate basin emissions.