During the early 1980's, there were projections of widespread destruction of lakes in the Adirondack region of New York State as a result of acidic precipitation. Although the Department of Environmental Conservation gathered data since 1977 on waters believed to be sensitive to acidification, a review of the chemistry and biology of these lakes provided an incomplete picture of past and existing conditions. It was clear that a more standardized, detailed and comprehensive survey was needed to examine the extent and magnitude of acidification of waters in New York State. In 1983, the Adirondack Lakes Survey Corporation, a NYS §401 not-for-profit corporation, was established to gather baseline information required to monitor environmental changes and provide a basis for policy decisions with regard to pollutants.

From 1984 to 1987, field investigators focused on the collection of detailed chemical, physical and biological data from 1469 Adirondack lakes and ponds ranging in size from about 0.5 to 700 acres. These data showed that 352 waters had pH values of 5.0 or less. Fish were not captured in 346 of the waters surveyed. The majority of acidified waters and those waters without fish captured were located in the western and southwestern Adirondack region. Waters in which fish were not captured were typically small (<10 acres), shallow (mean depth <10 feet) and located at high elevation (>2000 feet). Fishless waters were characterized as having low pH (<5.0), low acid neutralizing capacity (<0.0 µeq/L), low calcium concentrations and high aluminum values.

In 1988, the ALSC developed a proposal at the request of the United State Environmental Protection Agency (USEPA) to assist in a regional program to assess the impacts of episodic acidification on chemistry and fish communities in headwater streams as a result of storms and spring snowmelt. Intensive field studies were conducted for a period of two years in three specific areas of the Northeastern U.S. including Southwestern Pennsylvania, the Catskills and the Adirondacks. The ALSC contribution to this regional effort was the study of four headwater Adirondack streams located within a ten mile radius of the village of Eagle Bay. Stream chemistry parameters including pH, conductivity and temperature were continuously monitored. Automatic samplers were programmed to collect water samples at scheduled intervals during storm events and the spring snowmelt period. Samples were analyzed for 20 parameters to determine the duration and magnitude of chemical changes during specific events. ALSC personnel conducted intensive biological studies that included assessment of fish movement patterns using upstream/downstream fish traps and radio tagging of individual fish, periodic fish populations assessments and in-stream bioassays. The results of this project showed that it is difficult to isolate and quantify effects of episodic acidification. However, it is clear that the occurrence of certain events such as the spring snowmelt can result in major chemical changes that cause significant biological impacts. In streams where pH values were depressed to below 5.0 for more than several days during the snowmelt period, caged brook trout and blacknose dace experienced high mortality rates. In general, headwater Adirondack streams that are poorly buffered and experience episodic acidification have fewer fish and fewer species of acid-sensitive fish compared with streams that are adequately buffered and maintain pH above 5.0 during storm or snowmelt events. Since many of the headwater streams located in the acid-sensitive area of the Adirondacks are poorly buffered, episodic acidification may be responsible for reducing and, in some cases, eliminating many of these stream fish populations.