Increases in anthropogenic emissions of sulfur (S) and nitrogen (N) have resulted in increases in the associated atmospheric deposition of acidic compounds. In sensitive watersheds in the eastern United States, this deposition has initiated a cascade of negative environmental effects on aquatic ecosystems, resulting in a degradation or loss of valuable ecosystem goods and services. E&S scientist Timothy Sullivan teamed with scientists and an economist from the U.S. Forest Service, Washington State University, U.S. Environmental Protection Agency (EPA), and U.S. Geological Survey to synthesize the myriad impacts of air pollution on ecosystem services. Based on findings of an expert workgroup convened by the National Park Service, the assessment team synthesized information on acidic deposition-induced aquatic acidification from the published literature and linked critical load exceedances with ecosystem services and beneficiaries, using the Stressor Ecological Production function Final Ecosystem Services (STEPS) Framework and the Final Ecosystem Goods and Services Classification System (FEGS-CS) previously developed by the EPA. Experts identified and documented the sensitive aquatic ecosystem ecological endpoints valued by humans, and the environmental pathways through which these endpoints may experience degradation in response to acidification. Beneficiary groups were then identified for each sensitive ecological endpoint to clarify relationships between human well being and the effects of aquatic acidification, and to lay the foundation for future research and analysis to value these FEGS. Project completion date was May 2017. A peer reviewed journal article was produced.