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Acid Rain Program 2006 Progress Report
Published November 2007
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- 2006 Progress Report (PDF) (60 pp., 5.7 MB)
- Appendix A (Excel, 264 K) | Appendix A (PDF) (38 pp., 102 K)
- Appendix B1 (Excel, 249 K) | Appendix B1 (PDF) (36 pp., 63 K)
- Appendix B2 (Excel, 108 K) | Appendix B2 (PDF) (13 pp., 21 K)
- Interactive Mapping
- Press Release
Summary of the report results:
The Acid Rain Program was created to implement Title IV of the 1990 Clean Air Act Amendments. The purpose of Title IV is to reduce the adverse effects of acid deposition through reductions in annual emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) by 10 million tons and by 2 million tons below projected levels, respectively.
Sulfur dioxide (SO2) and nitrogen oxides (NOx) are the key pollutants in the formation of acid rain. These pollutants also contribute to the formation of fine particles (sulfates and nitrates) that are associated with significant human health effects and regional haze. Additionally, NOx combines with volatile organic compounds (VOCs) to form ground-level ozone (smog) and nitrates that are transported and deposited at environmentally detrimental levels in parts of the country. These pollutants, in their various forms, lead to the acidification of lakes and streams rendering some of them incapable of supporting aquatic life. In addition, they impair visibility in our national parks, create respiratory and other health problems in people, weaken forests, and degrade monuments and buildings.
In the United States, the electric power industry accounts for approximately 70 percent of total annual SO2 emissions and slightly more than 20 percent of total annual NOxemissions.
Since the start of the Acid Rain Program in 1995, the lower SO2 and NOx emission levels from the power sector have contributed to significant air quality and environmental and human health improvements.
Since its inception, the Acid Rain Program has:
- The ARP has reduced SO2 emissions by more than 6.3 million tons from 1990 levels, or about 40 percent of total power sector emissions. In 2006, annual SO2 emissions from ARP units fell sharply, with reductions of 830,000 tons from 2005 levels. Reduced demand, decreases in oil use because of fuel prices, and early Clean Air Interstate Rule (CAIR) compliance all appear to be factors in this decline.
- Total SO2 emissions fell below 10 million tons for the first time under the ARP. Sources emitted approximately 9.4 million tons of SO2 in 2006, below the emission cap of 9.5 million tons.
- With nearly 6.1 million unused (banked) allowances from prior years, SO2 emissions were 40 percent below the total 2006 allowable SO2 emissions of 15.7 million tons.
- Cut NOx emissions by 3.3 million tons from 1990 levels, so that emissions in 2006 were less than half the level anticipated without the program. Other efforts, such as the NOx Budget Trading Program (NBP) in the eastern United States, also contributed to this reduction.
- The ARP has contributed to significant decreases in acid deposition. For example, between the 1989-1991 and 2004-2006 observation periods, wet sulfate deposition decreased 35 percent in the Northeast and 33 percent in the Midwest. These reductions have resulted in positive changes in environmental indicators, including improved water quality in lakes and streams.
- Provided the most complete and accurate emission data ever developed under a federal air pollution control program and made that data available and accessible by using comprehensive electronic data reporting and Web-based tools for agencies, researchers, affected sources, and the public.
- Served as a leader in delivering e-government, automating administrative processes, reducing paper use, and providing online systems for doing business with EPA.
- Resulted in nearly 100 percent compliance through rigorous emissions monitoring, allowance tracking, and an automatic, easily understood penalty system for noncompliance. Flexibility in compliance strategies reduced implementation costs.
A 2005 study (PDF) (15pp., 532 K) estimates that in 2010, the Acid Rain Program's annual benefits will be approximately $122 billion (2000$), at an annual cost of about $3 billion - a 40-to-1 benefit-to-cost ratio.
The Acid Rain and Related Programs 2006 Progress Report expands on previous year's compliance reports to include special sections on issues related to status and trends in air quality, acid deposition and ecological effects, understanding the suite of Clean Air Rules, emerging issues related to sulfate concentrations, mercury monitoring and anticipated ecological effects of Clean Air rules implementation. Building on the Acid Rain Program model, EPA promulgated the Clean Air Interstate Rule (CAIR) in March 2005, to address transport of fine particles and ozone in the eastern United States, the Clean Air Mercury Rule (CAMR) to reduce nationwide mercury emissions from power plants, and the Clean Air Visibility Rule (CAVR) to improve visibility in national parks and wilderness areas.
SO2 Emissions from Acid Rain Program Sources
Please see the report for more detailed information or higher resolution images