As a result of state changes, MII methods must estimate emissions from operating conditions which were inactive during TD surveys or design TD surveys to better study the facility in all operating conditions. This implies that single snap-shot TD estimates are unlikely to replace annual BU inventory methods for midstream facilities until additional testing is completed, and that midstream facilities will require high-quality logging of operating state, per-unit and per-source emission factors and/or per-source measurements for the foreseeable future. This can be in the form of advanced monitoring and tracking systems of a facility's operational states, supplemented by identifying, measuring and including any unplanned emissions.