Lye Brook Wilderness Area

Index

Introduction

The Lye Brook Wilderness Area (18122 acres), designated by Congress in 1975, is located on the Green Mountain National Forest in Vermont. The Lye Brook Wilderness is east of Manchester Center in the southern Green Mountains of Vermont. This wilderness is named after Lye Brook, which flows through its western half. The wilderness ranges from 900 feet to 2900 feet above sea level. Most is above 2500 feet, on a high plateau with several ponds and bogs. Waterfalls and rocky streams may be found here as well as reflecting pools. The western section is extremely steep, facing west-northwest towards U.S. Route 7 and Manchester. Four and a half miles of the Appalachian/Long Trail cross the northwest tip of the wilderness.

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Air Quality Related Values

Visibility

Visibility is a mandatory air quality related value at most Class I wilderness areas, including Lye Brook Wilderness Area in the GMNF. Speciated fine particulate measurements have been taken since 1991 near the Lye Brook Wilderness Area (LYBR1) as part of the national IMPROVE (Interagency Monitoring of Protected Visual Environments) network (https://views.cira.colostate.edu/web/). The monitor at Mount Equinox, in Manchester, VT, is representative of Lye Brook Wilderness area. Visibility is variable throughout throughout the year, with some higher peaks in the summer. Fine ammonium sulfate particles account for the largest contribution to visibility impairment. IMPROVE data show that regional haze has decreased annually at Lye Brook Wilderness at a rate of approximately 3% per year. The Lye Brook IMPROVE monitor LYBR1 was replaced with LYEB1, at Mount Snow, in West Dover, VT, in 2012. Data from the new site is not yet available.

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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) 320 219 125 34 217 100
Haze Index (dv) 2.79 6.36 11.73 24.45 6.44 13.9

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Vegetation

Approximately 80% of the area is forested with northern hardwoods: birch, beech, and maple. Thickets of small spruce dot the area. Remnants of railroad grades and old logging roads remain. Several species of neotropical birds, black bear, moose, deer, pine martin and bobcat inhabit these woods. There are many marshy areas off trail and the ecological balance is quite fragile.

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Surface Water

The Vermont Department of Environmental Conservation has been sampling a number of GMNF wilderness ponds over the past few decades. Data collected at Bourn Pond and Branch Pond, in the Lye Brook Wilderness area, show an increase in both pH and ANC values (measured as Gran Alkalinity) using a Seasonal Kendal-Tau. Bourn and Branch Pond were listed as impaired waters for acid on the 2002 303(d) list for the US EPA. While the chemical conditions continue to improve, there has been no corresponding improvement in the biological condition. On-going reductions to air pollutants and replacement of earth metals through weathering needs to occur before biological recovery can occur.

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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 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 Higher level near-field screening and 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 Plume blight near-field 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.
Plume Blight Color Difference Index 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.

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AQRV Type: WATER
Sensitive Receptor Sensitive Receptor Indicator Thresholds
Aquatic Organisms Chemistry Sulfur deposition may significantly impact aquatic organisms at levels above 14 kg/ha/yr. Levels below 6 kg/ha-yr are not expected to significantly impact aquatic organisms.
Aquatic Organisms Chemistry Total sulfur plus 20% of nitrogen deposition at levels exceeding 16 kg/ha-yr may cause ANC loss that would impact aquatic organisms. Levels below 7 kg/ha-yr are not expected to significantly impact aquatic organisms.
Perennial Lakes and Streams Chronic Acid Neutralizing Capacity To maintain healthy biological functioning in perennial lakes and streams, the chronic acid neutralizing capacity must be >= 25 ueq/l. ANC's below 10 ueq/L (the red line) are expected to cause adverse effects.
Perennial Lakes and Streams Episodic Acid Neutralizing Capacity To maintain healthy biological functioning in perennial lakes and streams, the episodic acid neutralizing capacity must be >= 0 ueq/l.

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Pollutant Exposure Concern Thresholds
Pollutant Exposures Level Name Thresholds
Nitrogen EXCEEDANCE The Deposition Analysis Threshold for nitrogen deposition below which estimated impacts from a source are considered negligible is 0.010 kg/ha/yr.
S +20% N DEPOSITION Total sulfur plus 20% of nitrogen deposition at levels exceeding 12 kg/ha-yr may cause ANC loss that would impact aquatic organisms. Levels below 9 kg/ha-yr are not expected to significantly impact aquatic organisms.
Sulfur EXCEEDANCE 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.
Sulfur CHANGE Plume blight near-field 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.
Sulfur CHANGE 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.
Sulfur 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 %ile change in light extinction is <5% for each year modeled, when compared to the 20% best natural background values.
Sulfur EXTINCTION For sources generally further than 50 km from a Class I area, the visibility threshold for concern is not exceeded if the 98th %ile change in light extinction is <5% for each year modeled, when compared to the annual average natural condition value for that Class I area.
Sulfur CHANGE Higher level near-field screening and 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.
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.

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General Information
State(s):Vermont
County(s):Bennington and Windham
Forest Service Administrative Unit(s):Northern Region (Region 9) -- Green Mountain National Forest
Size:18,122 acres
Elevation Range:900 - 2,900 feet
Image(s):https://www.wilderness.net/images/
Detailed wilderness information:https://www.wilderness.net
GIS Map/Official Boundary:https://www.wilderness.net/NWPS/

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updated: 10/22/13