The Linville Gorge Wilderness, located in the mountains of western North Carolina, is part of the Pisgah National Forest. It was first designated a wilderness area in 1951. In 1964, with the signing of the Wilderness Act, Linville Gorge became one of the original components of the National Wilderness system and ecompassed 7,575 acres. The gorge is formed by Jonas Ridge on the east and Linville Mountain on the west and is bisected by the Linville River which drops 2,000 feet into the valley below. Elevations range from 1,300 feet on the Linville River to 4,120 feet on Gingercake Mountain. The terrain is extremely steep and rugged with numerous rock formations. It is covered by a dense hardwood/pine forest and a wide variety of smaller trees and other plants.
The Linville Gorge Wilderness has been designated as Class I air quality under the Clean Air Act Ammendments of 1977 and recent additions to the Wilderness has increased the size to 12,002 acres.
Air Quality Related Values (AQRV)
The scenic beauty of the landscape is an important characteristic of the wilderness and the attribute most highly valued by visitors. The visual resource includes the Gorge, and the Linville River, rock formations, old growth forests, and flowering vegetation. The Linville River has carved out one of the most rugged gorges in Eastern America. Cliffs and rock outcrops flank both sides of the steep narrow gorge. A chain of curious rock formations - Sitting Bear, Hawksbill, Table Rock, The Chimneys, and Shortoff Mountain create a distinctive profile along the eastern rim of the gorge. A variety of flowering plants, herbaceous and shrubs, occur around these rock formations. The Gorge is covered with an old growth forest dominated by large hemlocks and white pines that are impressive, even at a distance.
|Natural Background Visibility|
|Site Specific Rayleigh scattering coefficient:||Clearest 20% Natural||Clearest 20% 2000-2004 Baseline||Haziest 20% Natural||Haziest 20% 2000-2004 Baseline||Average Annual Natural||Annual Average 2000-2004 Baseline|
|Standard Visual Range (km)||279||133||132||22||192||56|
|Haze Index (dv)||4.07||11.11||11.22||28.77||7.58||19.56|
The wilderness vegetation is dominated by the majestic overstory of huge eastern hemlock and eastern white pine. These old growth trees dwarf and humble the visitor. Another important component of the vegetation is the variety of unusual plants that occur around the rock cliffs along the rims of the Gorge. Table Mountain pine, Carolina hemlock, Carolina and purple rhododerons, and sand myrtle are the most noticeable species. The Federally listed , threatened Hudsonia montana is found in only one other place besides the Linville Gorge Wilderness. Vegetation varies with elevation, exposure, soil type and moisture. The wilderness provides the unique opportunity of observing this variation as one travels down into the Gorge and back out again. Depending on which area of the wilderness you are in, you can explore the dark and humid recessses of the hemlock forest or the dry, pine forests with sweet smelling laurel, rhododendron and sand myrtle.
The Peregrin falcon, a State of North Carolina endangered species, can be seen hunting and soaring around the rock cliffs in the wilderness. The cliffs provide nesting sites for the falcon in an area where food is abundant.
Resource Concern Thresholds
|AQRV Type: VISIBILITY|
|Sensitive Receptor||Sensitive Receptor Indicator||Thresholds|
|Natural Visibility||Light Extinction||In specific Class I areas to maintain consistency with Regional Haze implementation plans or BART, the visibility threshold for concern is not exceeded if the 98th percentile change in light extinction is <5% for each year modeled, when compared to the 20% best natural background values.|
|Natural Visibility||Light Extinction||For sources generally further than 50 km from a Class I area, the visibility threshold for concern is not exceeded if the 98th percentile change in light extinction is <5% for each year modeled, when compared to the annual average natural condition value for that Class I area.|
|Plume Blight||Absolute Contrast||Screening Analysis: For near field sources (within 50 km of a Class I area), no additional analysis will be requested if screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions.|
|Plume Blight||Absolute Contrast||Refined Analysis: No further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 modeled against natural conditions.|
|Plume Blight||Color Difference Index||Screening Analysis: For near field sources (within 50 km of a Class I area), no additional analysis will be requested If screening analysis of a new or modified source can demonstrate that its emissions will not cause a plume with hourly estimates of DeltaE (color difference index) greater than or equal to 2.0 or the absolute value of the contrast greater than or equal to 0.05 when modeled against natural conditions.|
|Plume Blight||Color Difference Index||Refined Analysis: No further analysis will likely be requested if a new or modified source can show that impacts from a new or modified source will stay with the threshold of DeltaE <1.0 and |C| <0.02 when modeled against natural conditions.|
|Pollutant Exposure Concern Thresholds|
|Pollutant Exposures||Level Name||Thresholds|
|Nitrogen||DEPOSITION||Nitrogen deposition may be expected to cause cation leaching in soils when N levels are greater than 12 kg/ha/yr. Below 5 kg/ha/yr, negative effects to soil and vegetation are not expected|
|Nitrogen||EXCEEDANCE||The Deposition Analysis Threshold for nitrogen deposition below which estimated impacts from a source are considered negligible is 0.010. kilograms/hectare/year.|
|Ozone||W126||Biomass reduction of ozone sensitive species may occur when the W126 ozone metric (for April-September) is ≥ 14.5 ppm-hours. This should be evaluated in conjunction with the N100 value.|
|Ozone||N100||Biomass reduction of ozone sensitive species may occur when the number of hours from APRIL-SEPTEMBER with an ozone concentration greater than or equal to 0.100ppm equals or exceeds 4. This should be evaluated in conjunction with the W126 value.|
|Sulfur||DEPOSITION||Sulfur deposition may be expected to cause cation leaching and increased aluminum toxicity in soils when levels are greater than 20 kg/ha/yr. At 5 kg/ha/yr or below, sulfur negative effects to soil and vegetation are not expected.|
|Sulfur||EXCEEDANCE||The Deposition Analysis Threshold for sulfur deposition below which estimated impacts from a source are considered negligible is 0.010 kg/ha/yr.|
|Forest Service Administrative Unit(s):||Southern Region (Region 8) -- National Forests in North Carolina|
|Elevation Range:||1,650 - 4,120 feet|
|Detailed wilderness information:||https://www.wilderness.net|
|GIS Map/Official Boundary:||https://www.wilderness.net/NWPS/|