E&S Environmental Chemistry collaborated with scientists from the U.S. Geological Survey and U.S. Forest Service to assess the effects of acidic deposition on the current growth, health, and regeneration of sugar maple trees, and to determine the extent to which sugar maple response is associated with soil conditions in small upland watersheds within the Oswegatchie and Black river basins of the southwestern Adirondack Mountains in New York. We found essentially zero sugar maple regeneration at sites that had soil base saturation less than about 12%. This project represented a critical step in the assessment of chemical and biological acidification impacts and recovery responses of Adirondack terrestrial resources in response to changing levels of acidic deposition. The relationships between chemical indicators of soil acid-base chemistry (e.g., base saturation, exchangeable calcium and magnesium) and biological indicators of acidification effect on sugar maple (e.g., growth, health, regeneration) were quantified for use in critical loads modeling. Project completion was January 2013.