Lake sees return of namesake
By COLIN McDONALD Albany Times Union | August 13,2006
ALBANY, N.Y. ó Hidden among the steep ridge lines of the Adirondacks, Brooktrout Lake is a deep, cold and clear gem. Granite boulders line its shore in the shade of cantilevered maples, spruce and hemlocks. A lean-to and narrow footpath are the only obvious signs of human influence.
Brooktrout Lake was once a haven for its namesake, and New York's state fish had plenty of bugs to eat and nooks to hide in. But in the 1920s air pollution began to change the water. By 1984 acid rain had degraded it to the acidity of black coffee. That year biologists could not find a single living fish, and Brooktrout Lake joined the list of hundreds of other damaged Adirondack lakes ó places where people used to fish.
Now things are changing.
Recently a helicopter delivered 2,000 brook trout fingerlings. The 5-inch-long fish joined 20 adult trout that had already been dropped. Never before in the written history of the Adirondacks has a once-dead lake been restocked after improving on its own to the point of being able to support fish.
Brooktrout Lake is the first in the Adirondacks where scientists have documented significant natural recovery from the acidification caused by air pollution. It is a source of hope for the future.
At current levels of pollution the lake is expected to reverse its recovery in a decade.
"This is an experiment at the highest ecological level," said Charles Boylen, a biologist at Rensselaer Polytechnic Institute's Darrin Fresh Water Institute who has studied the lake since 1994. "We are not introducing game fish for people to come and fish out."
Brooktrout Lake is one of 35 lakes being studied by RPI as part of the Adirondack Effects Assessment Program under a $7 million grant from the U.S. Environmental Protection Agency.
What is known as acid rain is more accurately described as acid deposition because acid is deposited by westerly winds in the form of precipitation or particulate matter.
While the stocking is significant, scientists are more concerned about the condition of the soils in the watershed, specifically the amount of cations in the soil. Cations serve as natural anti-acid.
"All this is governed by the soils' ability to buffer or neutralize the acidities," U.S. Geological Survey hydrologist Douglas Burns said. "Research has shown that after many decades of acid rain these cations have been depleted from the soil surface."
The cations (pronounced CAT-eye-ons) come mainly from the erosion of rock, a short process on a geological scale, but one that could take generations before any noticeable increase of cations. The recent improvements in Brooktrout Lake are attributed not to an increase in the cations, but to a decrease in the rate they are being depleted because of less pollution.
"We're never going to get back to pre-industrial levels because we have messed the soils up too much," said Timothy Sullivan, who is constructing a mathematical model to predict the future of lakes in the region.
The newly released fish are from a heritage strain of brook trout, the closest living relatives to the now-extinct natives of Brooktrout Lake. For now, researchers know the lake's water probably won't kill the fish. If the trout establish a sustainable population, loons and herons will have something to eat. And the plankton and insects will adapt to sharing their habitat with a hungry predator.
It will be a huge step in regaining the natural balance of the lake. The first test will come in the spring, when the snow melts and dumps the sulfates and nitrates that accumulate in winter snow pack, causing the acidity of the lake to spike. If the fish make it through the year it will be a waiting game to see if they can reproduce.
Full-grown trout can handle greater variations in the acidity of water. But young fish and eggs are more delicate. If scientists see baby fish in a couple of years, they will know that Brooktrout Lake is capable of being more than just a holding pond.
"It's hard to say what it will do in the future because we don't understand why it has recovered so much more quickly than the other lakes," said Greg Lawrence, a hydrologist with the USGS office in Troy, N.Y.
Brooktrout Lake fills almost a third of its watershed. It has no lakes draining into it. It has a flush rate of 0.7 per year, meaning in less than 18 months all its water is replaced. The glaciers left it with thin soils. These factors make Brooktrout Lake particularly sensitive to changes in air pollution.