This project applied empirical and modeled critical loads (CLs) to fine-scale maps of selected national parks in the intermountain West that are considered to be most at risk from increases in atmospheric nitrogen (N) deposition from oil and gas-related activities. Different ranges of CLs are specified for a variety of vegetation types including lichens, forests, shrubs, and wetlands. Using fine-scale vegetation data, now available for many parks, CLs are mapped at a fine scale across individual national parks for a variety of terrestrial endpoints and receptors. Other CLs are compiled from the literature (e.g., for aquatic ecosystems) and are also mapped as appropriate. In addition, areas where CLs are exceeded by current nitrogen deposition are identified, using maps of total N deposition developed using an atmospheric transport and deposition model.
