Presidential Range - Dry River Wilderness Area

Index

Introduction

The Presidential Range-Dry River Wilderness area is located south of the 6288 foot Mount Washington, the highest summit in the northeast, and contains the large glacial cirque known as Oakes Gulf, which lies at the headwaters of the Dry River. This river - and just to the east the Rocky Branch - carve sharply down through the heart of this wilderness and offer contrast to the surrounding long, high ridgelines of the Southern Presidentials and Montalban Ridge. The Dry River is something of a misnomer, as anyone who has tried to cross it after a period of even moderate rain can attest. This, and the many other streams in this wilderness are flashy and swift, and run cold and clear from snow that melts well into the summer. The 27606 acre wilderness area, designated by Congress in 1975, is on the White Mountain National Forest in New Hampshire. This wilderness ranges in elevation from 880 feet to 5413 feet above sea level.

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Air Quality Related Values

Visibility

Visibility is a mandatory air quality related value at most Class I wilderness areas, including Presidential Range – Dry River Wilderness area in the WMNF. Speciated fine particulate measurements have been taken since 1995 near the Presidential Range – Dry River Wilderness area as part of the national IMPROVE (Interagency Monitoring of Protected Visual Environments) network (https://views.cira.colostate.edu/web/). The IMPROVE monitor at Camp Dodge, just south of Gorham NH, is representative of the Presidential Range – Dry River Wilderness area. Visibility is variable throughout the year, with some higher peaks in the summer. Fine ammonium sulfate particles account for the largest contribution to visibility impairment. Between 2001 and 2008, visibility at Camp Dodge improved at 3% per year.

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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) 289 191 122 40 203 101
Haze Index (dv) 3.73 7.66 11.99 22.82 7.07 13.77

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Vegetation

The area is characterized by mostly spruce-fir vegetation that runs from river bottoms onto the steep slopes of the high ridgelines. Changes in this pattern are found at the southern end of the wilderness where northern hardwood forests - spectacular in their autumn foliage - dominate, and in the northernmost section where the weather and soils dictate that only alpine-adapted plants will survive. Visitors may encounter deer, moose, black bear, or any of several other species of wildlife while traversing the area along approximately 43 miles of available hiking trails.

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Surface Water

Within the Presidential Range-Dry River Wilderness area, stream water quality monitoring has occurred in recent decades. The Wilderness Transect Study (1995-1997) monitored stream water chemistry in the Presidential Range-Dry River Wilderness to develop baseline data on water quality. This data was then used to determine additional investigations relating to the sensitivity of the ecosystems. The summertime stream monitoring effort (2001-present) sampled several sites in the wilderness area to measure the chemical output of the alpine vegetation community. It was found that monomeric aluminum was being mobilized with a strong correlation to hydrogen ions in the Presidential Range-Dry River alpine watersheds. More recently, data collected in 2011 from a low elevation site the Presidential Range-Dry River site had a stream pH value of 5.5, with a calculated ANC of 19.4 μeq/L (Murray, G. and C. Griffin. 2011. AMC 2011White Mountain National Forest Class I Wilderness Areas Air Quality Values Report. Unpublished.)

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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):New Hampshire
County(s):Carroll and Coos
Forest Service Administrative Unit(s):Northern Region (Region 9) -- White Mountain National Forest
Size:27,606 acres
Elevation Range:880 - 5,413 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