ALBANY, N.Y. -- A crystalline Adirondack lake once held up as an example of a ``dead" lake devastated by acid rain has now become a symbol of nature's ability to heal itself once pollutants are curbed.
As the name implies, Brooktrout Lake teemed with trout before air pollution from faraway cities began to change the chemistry of lakes and soils in the 6-million-acre Adirondack Park. In 1984, biologists found that Brooktrout Lake and hundreds of others in the region were devoid of fish.
Now there are signs of recovery. After the Clean Air Act amendments of 1990 tightened emissions limits on Midwest coal-burning power plants, acid rain decreased significantly. As expected, the pH levels of Adirondack lakes began to rise . The surprising thing, officials said, was how quickly it all happened.
``Nobody predicted Brooktrout Lake would come around as fast as it has," said Clifford Siegfried, director of the New York State Museum and a freshwater ecologist who has studied Adirondack lakes since 1984. ``Most predictions," Siegfried added, ``were for decades of recovery."
Last fall, biologists stocked Brooktrout Lake with 20 adult trout and 2,000 fingerling trout. It was the first time a once-dead Adirondack lake had been restocked with fish after improving enough to sustain fish.
The stocking is not for the benefit of anglers, but for scientists' review.
``This is a whole-lake experiment, an ecological experiment of the highest order," said Charles Boylen, a biologist at Rensselaer Polytechnic Institute's Darrin Fresh Water Institute.
Boylen has studied Adirondack lakes since 1994, under a $7 million grant from the Environmental Protection Agency.
``This is a great opportunity to see how nature deals with this phenomenon of acid recovery," he said.
This spring, researchers returned with sonar equipment to see how the fish had fared after snowmelt flooded the lake with a winter's worth of acid deposits. The fish survived.
The researchers will visit the lake every few weeks to observe the fish to see if they reproduce and grow. And they will monitor the entire ecosystem of the lake to document changes in plankton, algae, plants, insects, loons, salamanders, and other species, as the natural balance returns.
For ecologists, it will be interesting to watch what happens to the flora and fauna with the trout, Siegfried said. ``These communities have adapted to having no fish for several decades. The top predator is the midge larva," a wriggler the size of an eyelash. ``These are nice juicy morsels for trout. They'll likely wipe out that population."
The recovery of Brooktrout Lake may be short-lived, however. Tim Sullivan of E & S Environmental Chemistry in Corvallis, Ore., was contracted by New York S tate to develop mathematical models that predict what will happen in response to various levels of air pollutant emissions. The outlook is not good.
``While there has been a substantial decrease in acid deposition, the improvement in lake chemistry has been relatively small," Sullivan said. ``If we continue to operate under existing emissions regulations, the lakes that have been recovering will stop recovering and will start to get worse again over the next couple of decades. For some lakes, it will be worse than it ever has been."
That is because soils in the Adirondacks, particularly at higher elevations, have been depleted of calcium and other acid-neutralizing minerals, weakening their ability to serve as a buffer against acid rain, Sullivan said.
To prevent new acidification of the region's most sensitive lakes, such as Brooktrout, further emission controls are needed, he said.