Conclusion

EPA performs limited oversight of states’ processes for verifying the accuracy of emissions reports submitted by major sources. EPA’s data show that most emissions determinations are based on generic emissions factors. While EPA allows facilities to estimate their emissions in this manner, EPA officials generally consider direct methods to be more reliable. The accuracy of these reports is important because they influence (1) the financing of states’ regulatory programs through fees and (2) the development of emissions inventories, which, in turn, assist regulators in developing control strategies and establishing permit limits. Furthermore, steps taken to assess the accuracy of these reports—such as more thoroughly reviewing the supporting information—could provide benefits in terms of compliance with Clean Air Act requirements. For example, a more thorough review of the information underlying a facility’s emissions reports or a more systematic comparison of these reports over a period of time could identify indications of increased emissions. Such indications could, in turn, trigger a review of compliance with New Source Review requirements, an area where EPA found widespread noncompliance in four industries. The state that performed the most detailed reviews found widespread inaccuracies. While taking steps to improve its overall compliance-monitoring strategy, EPA does not plan to evaluate state processes for verifying emissions reports from large facilities.
What GAO Found

The Environmental Protection Agency (EPA) performs limited oversight of states' processes for verifying the accuracy of large industrial facilities' emissions reports. EPA's data show that most emissions determinations from large sources are based on generic emissions factors. Although EPA allows facilities to estimate their emissions in this manner, EPA officials generally consider direct methods to be more reliable. The accuracy of these reports is important because they influence (1) the financing of states' regulatory programs through fees and (2) the development of emissions inventories, which, in turn, help regulators to develop control strategies and establish permit limits. Furthermore, steps taken to assess the accuracy of these reports, such as more thoroughly reviewing the supporting information, could improve compliance with Clean Air Act requirements. For example, a more thorough review of the information underlying a facility's emission reports, or a more systematic comparison of these reports over time, could identify increased emissions. Such indications could, in turn, trigger a review of compliance with new source review requirements, an area in which EPA found widespread noncompliance in four industries. In the four states that GAO reviewed, the states that had done the most detailed reviews found widespread inaccuracies. Although it is taking steps to improve its overall compliance monitoring strategy, EPA does not plan to evaluate states' processes for verifying emissions reports from large facilities.