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 were specified for a variety of vegetation types including lichens, forests, shrubs, and wetlands. Using fine-scale vegetation data, CLs were mapped across individual national parks for a variety of terrestrial endpoints and receptors. Other CLs were compiled from the literature and were also mapped. In addition, areas where CLs were exceeded by current N deposition were identified, using maps of total N deposition developed using an atmospheric transport and deposition model. Project completion was August 2014.