Aspen prepared an EIS for the USDA Forest Service's Lolo National Forest to evaluate the potential environmental impacts associated with Yellowstone Pipe Line Company's application to build a new 67-mile section of its petroleum products pipeline in Western Montana, as well as to renew its special use permit for 82 miles of existing pipeline. The proposed project was highly controversial, and the NEPA process included an extensive public participation program, which involved numerous scoping and public meetings throughout the study area. Aspen prepared the air quality section for the Yellowstone Pipeline EIS.