The potential climate benefits of increased utilization of natural gas depend critically on the total methane leak rate from the entire natural gas system. He goal of this project is to quantify facility-level emissions of methane, oxides of nitrogen (NOx), and select volatile organic compounds (VOCs) from wells, compressor stations, processing plants, and other types of facilities in the Denver-Julesburg and Uintah basins in Colorado/ Utah and the Barnett shale in Texas using dual-tracer-flux ratio techniques and upwind, offsite tracer release. The technique allows quantification of the facility-level emission rate without use of an inverse model. As part of this project the following tasks will be accomplished: �?� Development and evaluation of offsite tracer release approach �?� Downwind tracer flux measurements at gas sites �?�Quantification of the emission rates of methane from abandoned facilities in Appalachia The new emission data will be used to develop distributions of methane emissions by facility type (e.g. well-head, compressor station) and region.