Society has made great strides in addressing the issue of acid deposition. These successes should be celebrated.

In 1990 the U.S. Congress passed amendments to the Clean Air Act designed to decrease emissions of the two gasses that are the primary causes of acid deposition. Sulfur dioxide (SO2) emissions were to be decreased by 10 million tons. Nitrogen oxides were to be decreased by 2 million tons. The cost of meeting these goals was estimated at $4.5 to $7.5 billion. Even with this huge expenditure, some in the electric industry doubted the goals could be met.

In 1995, the first year these standards went into effect, SO2 emissions dropped by 3 million tons. A 1998 Resources for the Future report estimated that the cost of meeting the goals set in 1990 would be less than $1 billion. Not only did emissions decrease faster than required by federal regulations, but they did so at a cost that was only a fraction of early estimates. How did this happen? SO2 was regulated using an innovative cap and trade program that allowed companies to trade "emission allowances." This market based approach gave companies the flexibility to choose the most cost effective method to decrease emissions while simultaneously providing a strong market incentive to do so.

Before the program began, many experts worried that companies in the Midwest would simply purchase emission allowances instead of decreasing emissions. However, it appears that it was more cost effective to decrease emissions rather than buy credits. Emissions in the Midwest were decreased by similar proportions compared to other regions of the United States (more than the West and South, less than the Northeast and Mid-Atlantic).

With decreasing SO2 emissions, the pH of rainfall has increased over much of the United States, including the Adirondacks. Rainfall pH is still more acidic than natural rainfall, but not as acidic as during the early 1980s. In New England, the sulfate deposition has decreased by about 25%, and some lakes there appear to be recovering, but the Adirondacks have not faired so well. While past successes are heartening, it is clear that more still needs to be done.