Acid Rain Program 2003 Progress Report

Summary

Figure 1: Trends in SO2 emissions since 1980 for all Title IV affected sources. Click above image to view larger chart.

Congress created the Acid Rain Program in Title IV of the 1990 Clean Air Act Amendments. The Acid Rain Program has the goals of lowering the electric power industry’s annual emissions of:

• Sulfur dioxide (SO₂) to half of 1980 levels, capping them at 8.95 million tons starting in 2010, and
  
  
• Nitrogen oxide (NO_X) to 2 million tons lower than the forecasted level for 2000, reducing annual emissions to a level of 6.1 million tons in 2000.

In 2003, Acid Rain Program emission controls on the electric power industry resulted in:

• SO₂ emissions of 10.6 million tons, a reduction of 38 percent from 1980 levels. (See Figure 1) Emissions were 0.4 million tons higher in 2003 than in 2002. This small increase resulted from increased production of electricity by coal-fired and oil-fired units that emit much more SO₂ than natural gas units that generated less power in 2003. The main cause of this was the substantial increase in natural gas prices. Large, early SO₂ reductions that were very beneficial at the program’s outset enabled banked allowances to be available to cover these emissions.
  
  
• NO_X emissions of 4.2 million tons, which were close to 4 million tons less than the emissions forecasted for 2000 (See Figure 2). Other regulations, such as the NO_X Budget Program in the Northeast, also contributed to this reduction in emissions.

Figure 2: Trends in NOX emissions under the Acid Rain Program. Click above image to view larger chart.

As in years past, the electric power industry achieved nearly 100 percent compliance with Acid Rain Program requirements — only 1 unit had emissions exceeding the SO₂ allowances that it held and no units were out of compliance with the NO_X program. This exceptionally high level of compliance was, in part, achieved as a result of the Acid Rain Program’s continued provision of accurate and complete SO₂ and NO_X emissions data. This process was augmented by a substantial auditing effort and accountability through rigorous, yet streamlined, reporting systems.

SO₂ and NO_X 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 health effects and regional haze. Additionally, NOX combines with volatile organic compounds (VOCs) to form ozone (smog), and nitrates that are transported and deposited at environmentally detrimental levels in parts of the country. The United States (U.S.) electric power industry accounts for approximately 67 percent of total annual SO₂ emissions and 22 percent of total annual NO_X emissions.

Since the Acid Rain Program began in 1995, the lower SO₂ and NO_X emissions levels from the power sector have contributed to significant air quality and environmental improvements that EPA’s Clean Air Status and Trends Network (CASTNET) and other long-term environmental monitoring networks are reporting.

Over the last decade:

• Ambient SO₂ and sulfate levels are down more than 40 percent and 30 percent, respectively, in the eastern U.S.
  
  
• Wet sulfate deposition, which acidifies sensitive lakes, streams and forest soils, has decreased 39 percent in the northeastern U.S. and 17 percent in the southeastern U.S. (See Figure 3)
  
  
• Some modest reductions in inorganic nitrogen deposition and wet nitrate concentrations have occurred in the Northeast and Mid-Atlantic regions, but other areas have not shown much improvement.
  
  
• Signs of recovery in acidified lakes and streams are evident in the Adirondacks, the northern Appalachian Plateau, and the upper Midwest. These signs include lower concentrations of sulfates, nitrates, and improvements in acid neutralizing capacity. Response of surface water chemistry to the Clean Air Act Amendments of 1990.

Annual Mean Wet Sulfate Deposition 1989 through 1991 Annual Mean Wet Sulfate Deposition 2001 through 2003 Figure 3: Wet sulfate deposition decreased throughout the early 1990s in much of the Ohio River Valley and Northeastern U.S. Other less dramatic reductions were observed across much of New England, portions of the Southern Appalachian Mountains and in the Midwest. Average decreases in wet deposition of sulfate range from 39 percent in the Northeast to 17 percent in the Southeast. Click images to view larger maps.

Additional Information

The Clean Air Interstate Rule

Response of Surface Water Chemistry to the Clean Air Act Amendments of 1990
(PDF 92 pages, 4.6 MB)

Valuation of Natural Resource Improvements in the Adirondacks
(PDF 51 pages, 1.5 MB)

"Lessons from Phase 2 Compliance with the U.S. Acid Rain Program"
(PDF 23 pages, 390 KB)

“SO2 Control by Electric Utilities: What are the Gains from Trade?”
(PDF 37 pages, 166 KB)

Information on Cap and Trade

Acid Rain Program

Acid Rain Reports from Prior Years

Data and Maps

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