This proposed rule will reconsider the “Mandatory Reporting of Greenhouse Gases” (74 FR 56260; October 30, 2009) and all later rules that have amended that rule. These rules comprise the Greenhouse Gas Reporting Program which requires reporting of greenhouse gas (GHG) data and other relevant information from certain large GHG emission sources, fuel and industrial gas suppliers, and CO2 injection sites in the United States. A total of 46 industrial sectors are required to report under the program, including more than 8,000 facilities. Facilities determine whether they are required to report based on the types of industrial operations, their emission levels, or other factors. Facilities generally have the flexibility to choose among several methods to compute GHG emissions. The decision of which method to use may be influenced by the existing environmental monitoring systems in place and other factors. Facilities can change emission calculation methods from year to year and within the same year, as long as they meet the requirements for use of the method selected.