But, while the situation may be improving, many of the lakes still have a long way to go before they can fully support aquatic life. If current levels of acid rain are maintained, it will be several decades before the region sees total recovery, the researchers predict.
The findings are scheduled to appear in the May 15 print edition of Environmental Science & Technology, a peer-reviewed journal of the American Chemical Society, the world's largest scientific society. The article was initially published April 11 on the journal's Web site.
"This is clear evidence that the Clean Air Act is working," says Charles Driscoll, Ph.D., a professor of civil and environmental engineering at Syracuse University and lead author of the paper. "This is the first time in a peer-reviewed journal that we can say the Adirondacks are showing significant numbers of lakes recovering. It means we've now turned the corner and we're starting to see some improvement."
Acid rain generally occurs when sulfur dioxide in the air (mostly from electric utility emissions) mixes with precipitation to form sulfuric acid, which is then deposited in watersheds. Sulfur dioxide emissions have decreased dramatically since the 1970 Amendments to the Clean Air Act. Emissions peaked in 1973 and have declined almost 40 percent since that time, according to the U.S. Environmental Protection Agency.
The Adirondack region encompasses a giant swath of land in northern New York, including the 6-million-acre Adirondack Park a densely forested cluster of mountains spattered with almost 3,000 lakes and ponds.