Because of their unique importance, national parks, national monuments, wilderness areas, and other special use areas receive a Class I designation. Class I areas are provided special protection from air pollution impacts.
The Great Sand Dunes National Park is the closest Class I area to the Project. It is located approximately 250 miles west of the Project in southern Colorado. Computer modeling using the VISCREEN program was conducted to determine whether the Project would have an adverse effect on that Class I area. Results of the modeling showed that the Project will be below the significance screening level and will not adversely affect visibility at the Great Sand Dunes National Park.