Five major findings emerge from the results of the scientific synthesis of mercury in New York State:

1. New York State features natural areas that are ecologically, culturally, and economically significant but widely contaminated with mercury largely due to atmospheric emissions and deposition.

2. The scope and intensity of the impact of mercury on fish and wildlife in New York State is much greater than previously recognized. Mercury concentrations exceed human and ecological risk thresholds in many areas, particularly in inland waters.

3. The Adirondacks, Catskills, and parts of Long Island are sensitive to mercury pollution. The impact of mercury emissions and deposition is exacerbated by landscape characteristics. Abundant forests facilitate mercury deposition. Wetlands enhance transport, methylation, and uptake leading to elevated concentrations in aquatic and terrestrial food webs.

4. Mercury concentrations in the environment of New York State have declined over the last four decades, concurrent with decreased air emissions from regional and U.S. sources. After initial declines, however, concentrations of mercury in some fishes and birds from certain locations have stabilized or even increased in recent years—revealing how trajectories of mercury recovery can be complex.

5. While the timing and magnitude of the response will vary, further controls on mercury emission sources are expected to continue to lower mercury concentrations in the food web yielding multiple benefits to fish, wildlife, and people of New York State. It is anticipated that improvements will be greatest for inland lakes and will be roughly proportional to declines in mercury deposition.

Efforts to advance recovery from mercury pollution in New York State in recent years have yielded significant progress, but have yet to address the full scope of the problem. The findings from this scientific synthesis indicate that: (1) mercury remains a pollutant of major concern; (2) the extent and intensity of the contamination is greater than previously recognized; and (3) after decades of declining mercury emissions, trends in mercury concentrations in fish and wildlife have stabilized or are increasing in some species in particular areas.

While the reasons behind these shifting trends require further study, they also underscore the need to continue and even expand existing monitoring efforts by NYSERDA and other entities to better track progress. This is particularly important as new pollution mitigation measures are implemented, as global sources increase, and as the region faces changing environmental conditions.