Acid rain is leaving the Adirondacks, but scientists say restoration is still a long way off

Paul Casson of the SUNY Albany Atmospheric Sciences Research Center stands with a cloud collection device on the roof of the three-story Whiteface Mountain Field Station building, atop the 4,865-foot summit of Whiteface Mountain in Wilmington in August 2016. (Enterprise photo — Antonio Olivero)

WILMINGTON — Scientists say data on acid rain collected at an observatory on the summit of Whiteface Mountain tell a success story stretching over the past five decades. This story, they say, is one of science, government policy and environmental activism converging to make direct improvements to the air, water, soil and precipitation.

But that victory is far from over.

Recent data from the Whiteface Mountain Atmospheric Sciences Research Center shows that the pH balance of precipitation and cloudwater rose over the past two years, continuing a positive trend that began back in the 1970s. Higher pH means the water and snow are less acidic.

Acid rain is generally considered to be in the 4 to 5.5 pH range. Normal rain is around 5.6 pH. Rainwater at Whiteface is now at 5.3 pH.

Clouds typically show a lower acidity, because of dilution. Cloudwater at Whiteface is at 5.6 pH.

(Provided graphic — National Atmospheric Deposition Program)

This is also shown in data showing precursors to acid rain have become less common in clouds at Whiteface.

Though the chemicals that killed plants and animals throughout the 20th century have been reduced, these experts say that does not mean it is time to slow down. Recovery of these natural resources will take years, decades and even centuries, they say, and they believe vigilance in climate science, government regulation and monitoring are important to heal the wounds human industry has dealt to the environment.

Charles Driscoll, a professor of environmental systems at Syracuse University, said globally, air quality has greatly improved since the mid-20th century and that the Whiteface data shows it is happening in the Adirondacks, too.

Some scientists credited the Clean Air Act amendment of 1990. Some mentioned New York state, which got rid of oil- and coal-fired power plants and started a cap-and-trade pollution program with neighboring states.

“The Clean Air Act and all coal-fired power plants in the Midwest had to do to clean up their emissions has actually resulted in improvement in the water chemistry and the health of lakes in the Adirondacks,” said Dan Kelting, executive director of the Adirondack Watershed Institute at Paul Smith’s College. “What you’re seeing at Whiteface is direct evidence of the decrease in acidity.”

This decrease comes as the Energy Information Administration reports levels of coal consumption are at record lows.

“The two are definitely correlated,” said Richard Brandt, science manager for the University of Albany’s Whiteface observatory.

Paul Smith’s College professor and climate scientist Curt Stager said this decrease is a good example of successful legislation. Air and water got cleaner, and industries did not go out of business.

“New York state led the way, and the Environmental Protection Agency did great work getting other states to cooperate,” Stager said. “That’s what big government is for, to do good work for everybody.”

He believes similar models can be used to address climate change as a whole.

Whiteface data

Brandt said the University of Wisconsin’s National Atmospheric Deposition Program, which commissions and studies the data gathered from the observatory atop the 4,865-foot-tall Whiteface, has measured summit cloudwater and ground-level precipitation since the 1970s.

The recent data shows the lowest acid levels measured regularly since the 1970s, he said. The acidity was likely lower before the NADP started measuring, he added, as there were fewer sources of the chemicals that cause acid rain. Data in the NADP’s chart ranges from 1995 to 2020.

The chart shows a big rise in summit cloudwater pH in both 2019 and 2020 after a dip in 2017 and 2018. Precipitation at the lodge has been on a more steady, slow, rise upward in its pH balance.

There are also dramatic changes in acid rain precursors NOy (nitric oxides) and SO2 (sulfur dioxide) — byproducts of burning coal that make water more acidic.

SO2 at Whiteface has steadily decreased significantly since 1995, from 1.5 parts per billion to 0.1 ppb.

NOy at Whiteface has risen and fallen in that time period, spiking from 1995 to 2005 from under 2 ppb to over 3 ppb. Since then, though, it dropped again to around 1 ppb.

Recovery chain reaction

Though acid rain’s presence has been diminished, in many places the damage has already been done. Decades of exposure has left many water bodies with lower biodiversity and removed their protective layer of minerals. At one point, some 700 Adirondack water bodies were dead, devoid of life. Most have recovered, but not all the way.

If acid rain rises again, the land will not be able to withstand it as well as before.

“Some of these environments have depleted their neutralizing capacity, so they’re more sensitive than they had been at the beginning,” Brandt said

Acid rain hurt the environment through an interconnected chain reaction. Damage to trees, soil, water, microbes and larger animals compound each other and spread acids’ sterilizing properties.

The environment will also recover through a similar chain reaction, which starts as soon as the chemical makeup of rain changes. But it will never recover back to its original state.

“Once you skew something as complicated as an ecosystem, it’s hard to get all the way back to where you were,” Stager said. “It’s now a ‘novel ecosystem,’ a new ecosystem.”

Stager said Bear Pond near Upper St. Regis Lake was for years a “classic” acid rain site.

“It was as clear as a swimming pool in the 1980s,” Stager said. “It was actually attractive because it was sky blue. … People would go there because it was so clear, not realizing why.”

It was because the water was sterilized. Acid rain had rid the water of plankton, plant life and minerals.

Stager said it took around 20 years for the pond to return to a more natural, murky state after the 1990 Clean Air Act amendments.

“If you go there now, it looks like a lot of other lakes,” Stager said. “If you knew it back then, you’d say, ‘What happened to Bear Pond?’ That’s because it’s recovered.”

He said it is easy to take these things for granted because they have not been an issue for many years.

“It looks like this because we succeeded, but we’ve still got a lot to do,” Stager said.

Driscoll said improvement in streams is less consistent than in lakes, as the factors that contribute to moving waters’ pH balance fluctuate more.

Driscoll said chemistry changes occur fast in waters, and slower in soil.

He said acid rain washed calcium and magnesium out of the soil during the 1900s. Restoration of those minerals occurs when rocks break down.

Restoration occurs even slower in biological life, he said. Trees such as sugar maples have been damaged, and Driscoll said they will not be able to return to the state they were in before human alteration.

Restoration of the ecosystem into a new, healthier form will take centuries, he said.

Driscoll said climate change also slows recovery in soil. With more rain, a symptom of climate change, comes more flushing of the soil’s minerals.

However, some species find a changing climate helpful. Red spruce trees are seeing a faster recovery from acid rain because of climate change. Acid rain leeched calcium from these trees’ needles, making them more susceptible to cold, so warmer average temperatures help the red spruce.

There are “winners and losers” with climate change, Driscoll said.


Some lakes are recovering naturally, Brandt said. For example, brook trout were discovered in Lake Colden up in the High Peaks Wilderness in 2019, after years of the water body being deemed “fishless.”

At times, limestone has been used by private and public groups to raise the pH of waters and soil by artificially adding calcium to the land. Last year New York state said it had no more lakes on its list to lime.

Stager compared this practice to an antacid pill, saying that it lessens the symptoms for a time but is only a temporary fix. Kelting said adding lime to lakes also supports restoration of important nutrients in soil. It is effective but expensive, and needs to be done consistently.

Driscoll said there are no known side effects to liming water.


The only true solution to acid rain and its damages, each expert said, is to transition away from fossil fuel energy. They said the current energy system is old and inefficient, and that new energy sources could create new jobs, save lives and do that at a cost not much greater than the current system.

“It has to happen eventually because we’re going to run out of fossil fuels,” Stager said.

This may seem unlikely, but Stager said it is not.

“Just like in the old days people never imagined running out of whale oil,” he said. “It’s just a question of, are we going to do it in advance, under control? Or are we just going to do it because we ran out? Either way there will have been an ‘acid rain century’ in the legacy of the lake sediments and the history of the planet.”

He said the biggest successes are always slow but are important to recognize. Negative big changes can happen gradually, too, he said, which makes them easy to neglect.

“It doesn’t mean we stop being vigilant,” Stager said. “It means we keep doing what we’re doing because it works.”

“Policy works, and we need to have the monitoring to show that it works,” Kelting said.

The observatory at Whiteface celebrated 50 years of measurements last year, though the landmark came with little fanfare because of the COVID-19 pandemic. Brandt said the research done there is crucial to understanding the state of acid rain, with data showing both the good and the bad.

“These plots are a good reason to be doing monitoring at Whiteface,” Brandt said.


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