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Environmental Impacts of Acid Deposition: Lakes

Photo of a lake that have been damaged by acid deposition in the way of wildlife depletion

This photograph shows a lake in the Adirondacks which has been affected by acid deposition, eliminating fish and many other aquatic species.

Effects of Acid Rain on Adirondack Lakes

From: Wild in New York
Spring 1998

Twenty years ago, we all found it hard to believe that rain water could be killing Adirondack fish. Today, after spending millions of dollars on research to understand the problem and millions more to reduce air pollution, we expect to see some changes. So, what is the status of our acid lakes? Are the lakes in the Adirondacks recovering? And what are the Department and Division of Fish, Wildlife and Marine Resources doing to help solve the problem?

The Problem

Acid rain is a by-product of our industrialized society. Air pollution combines with water in the atmosphere and falls to the earth as rain or snow. While many areas of New York State are not sensitive to the acidity because of limestone deposits or soils which neutralize the acid, regions like the Adirondacks, Catskills, Hudson Highlands, Rensselaer Plateau and parts of Long Island are particularly sensitive to acidic deposition. The soil and bedrock in these areas are not able to counteract the acid in the rain and snow. Consequently, although most of the resource is healthy, some rivers and lakes in these areas became acidified.

In the Adirondack region, acidic deposition has affected hundreds of lakes and thousands of miles of headwater streams. The diversity of life in these acidic waters has been greatly reduced. Fish populations have been lost, and loons and otters have moved to other lakes where they can find food.

Combating Acid Rain

Since air pollution and acid rain do not recognize boundaries, fighting acid rain is a complicated, nation-wide issue. New York State has worked hard to reduce air pollution from sources within the state and was the first state to pass an acid deposition control act in 1984. Then in 1990 the federal government passed Clean Air Act Amendments that included significant acid rain control programs. Phase I of the federal sulfur control program began in January 1995.

For New York, federal programs are essential since most of our acid rain originates outside of the state. By nature of our location, New York State is downwind from many industrialized areas and large coal burning power plants of the Ohio River Valley. In 1996, power plants in Ohio produced six times more sulfur dioxide and eight times more nitrogen oxides than power plants in New York State.

The Division of Fish, Wildlife and Marine Resources and other divisions within DEC have played an active role in helping to understand and solve the acidic deposition problem. During the 1980s, DEC conducted detailed research projects and extensive surveys to document the problem. Studies included: monitoring fish survival in caged fish studies; fitting brook trout with transmitters and following them to determine where they went during snowmelt; and measuring fish populations before and after acidic periods. Thousands of lake and stream water samples were analyzed, and acidified lakes were found just a short distance from healthy lakes. Nearly 1,500 Adirondack lakes were surveyed to assess the fish populations. Reports from these projects, along with many others, provided the science leading to passage of the acid rain section of the Clean Air Act Amendments.

Since about 1990, the Division of Fish, Wildlife and Marine Resources has shifted away from acid rain research and concentrated more effort toward monitoring the resource, reviewing EPA reports, and working with the EPA to ensure that acidic deposition levels are adequately reduced. A total of 52 Adirondack waters are monitored monthly to document any changes in water chemistry due to changes in acidic deposition.

The Future of Acid Rain

While the Clean Air Act Amendments focus has been on sulfate reductions, recent information has shown that nitrate is also an important acidifying chemical, especially during the spring snowmelt period when streams and lakes are most acidic. This indicates that there also need to be controls for large reductions in nitrate deposition. Sources of nitrate air pollution include cars, trucks and power plants.

Future efforts to control urban smog during the summer season will result in some reductions, however additional nitrate reductions are needed. A recent EPA report which used computer models to predict future lake acidity reported that without additional reductions in emissions, the number of acidic Adirondack lakes will actually continue to increase.

The Outlook

Over the past few years we have realized that we now have a good news-bad news story to report. The good news is that emissions of sulfur dioxide have been reduced, and as a result acidic deposition of sulfate has decreased approximately 25%. This has led to lower levels of sulfate in Adirondack lakes and streams. The bad news is that we have not observed the large scale improvements in the acidity of Adirondack waters that we had anticipated. Part of the reason is that in addition to decreases in sulfate in rain water, there have also been decreases in calcium, magnesium and other basic compounds in rain water which help to neutralize the sulfate. These decreases occurred because we have greatly reduced the particulate or soot portion of air pollution, and in the process we have reduced certain compounds which previously helped to neutralize the acidity of our rain and snow.

While we discuss the merits of various emissions control programs, the Adirondack resource continues to suffer the impacts of acidic deposition. I grew up fishing on the Moose River near McKeever and wondered why we never caught any fish other than the ones the Conservation Department had stocked earlier that year. Now I know that the Moose River was, and still is, an acid-impacted river, and probably few trout can survive the acidic snowmelt period.

It is a hopeful sign that sulfate concentrations are declining in Adirondack waters. However, we must continue to push for additional acid rain controls, so that fish populations in former brook trout ponds can be reestablished. Reducing acidic deposition should result in a true recovery to a healthy, diverse resource and a return of fish populations to lakes which are presently too acidic to support fish.

For more information contact:
Mr. Howard Simonin
NYSDEC - Rome Field Station
8314 Fish Hatchery Road
Rome, New York 13440
Phone: 315-337-0910

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