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5.0 Assessment of Baseline and Natural Conditions

Under Section 169A(b)(2)(B) of the Clean Air Act, the initial Regional Haze SIPs 

must contain measures to make reasonable progress toward the goal of achieving 

natural visibility. Comparing natural visibility levels to current baseline conditions 

helps determine how much progress should be made in the next five to 10 years. 

Determining natural visibility conditions is a SIP element and each state 

containing a Class I area (in consultation with Federal Land Managers and other 

states) was required to estimate natural visibility levels. New York State contains 

no Class I areas and, as such, this assessment is not required. However, it is 

presented here for informational purposes. 

Additionally, Section 51.308(d)(4)(iii) of the EPA’s Regional Haze Rule, 40 CFR 

51.308 requires the inclusion in the SIP of a description of procedures by which 

monitoring data and other information are used in determining the contribution of 

emissions from within the state to regional haze visibility impairment at mandatory 

Class I Federal areas both within and outside the state. The Interagency 

Monitoring of Protected Visual Environments (IMPROVE) program was developed 

in 1985 to establish current visibility conditions, track changes in visibility, and 

help determine the causes and sources of visibility impairment in Class I areas. 

IMPROVE data was used to calculate baseline and natural conditions for MANEVU Class I areas. Data from the following IMPROVE monitors (see Table 5-1 

below) is representative of Class I areas in and near MANE-VU. 
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Table 5-1- IMPROVE Information for MANE-VU Class I Areas 

Class I Area IMPROVE 

Site

Location (latitude 

and longitude) State

 Acadia National Park ACAD1 44.38, -68.26 Maine 

Moosehorn National Wildlife 

Refuge MOOS1 45.13, -67.27 Maine 

Roosevelt/Campobello 

International Park MOOS1 45.13, -67.27 Maine 

Great Gulf Wilderness Area GRGU1 44.31, -71.22 New Hampshire 

Presidential Range/Dry 

River Wilderness GRGU1 44.31, -71.22 New Hampshire 

Lye Brook Wilderness Area LYBR1 43.15, -73.13 Vermont 

Brigantine Wilderness Area BRIG1 39.47, -74.45 New Jersey 

Source: VIEWS (http://vista.circa.colostate.edu/views/), prepared on 7/06/06

5.1 Natural Conditions

In September 2003, the EPA issued guidance for a calculation of natural 

background and baseline visibility conditions. EPA guidance gives states a 

“default” method to estimate natural visibility. Natural visibility represents the 

visibility for each Class I area that is representative of existing conditions before 

human activities affected air quality in the area. MANE-VU estimated natural 

visibility using the default method for the 20% best and worst days, and also 

evaluated ways to refine the estimates. Potential refinements included increasing 

the multiplier used to calculate impairment attributed to carbon, adjusting the 

formula used to calculate the 20% best and worst visibility days, and accounting 

for visibility impairment due to sea salt at coastal sites. However, MANE-VU 

found that these refinements did not significantly improve the accuracy of the 

estimates and MANE-VU states desired a consistent approach. Therefore, default 

estimates were used. 

Once the technical analysis was complete, MANE-VU provided an opportunity to 

comment to federal agencies and stakeholders. After serious consideration of the 

comments that were received, in December 2006, MANE-VU recommended 

adoption of the alternative reconstructed extinction equation for use in the 

Regional Haze SIPs. Therefore, default estimates were used with the 
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understanding that this would be reconsidered as better scientific understanding 

warranted. 

Notwithstanding the above, New York State does not contain any Class I areas 

and so is not required to estimate reasonable progress goals. However, as 

described in Section 3, the Department has coordinated with states containing 

Class I areas which are affected by emissions from sources located in New York 

as those states assessed baseline, natural and current visibility conditions in their 

respective Class I areas. The results of this work were used to determine the 

control measures whose implementation would be necessary by New York and 

other contributory states to meet reasonable progress goals for each Class I area. 

5.2 Baseline Visibility

A five-year average (2000 to 2004) baseline visibility in deciviews was calculated 

by MANE-VU for each Class I Area for the 20 percent best and 20 percent worst 

days in accordance with 40 CFR 51.308(d)(2) and as detailed in Appendix L of the 

document entitled Baseline and Natural Background Visibility Conditions

(NESCAUM, December 2006). The deciview visibility for these worst and best 

days are based on calculations and data included in Appendix C, Guidance for 

Estimating Natural Visibility Conditions Under the Regional Haze Rule of this SIP 

submission. 

Table 5-2 presents the IMPROVE program calculations for the 20 percent worst 

and best baseline (2000-2004) visibility conditions for each IMPROVE monitoring 

site at MANE-VU Class I Areas. These values are posted on the Visibility 

Information Exchange Web System (VIEWS) operated by the Regional Planning 

Organizations (available online at http://vista.cira.colostate.edu/views/). 
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Table 5-2 - Baseline Visibility for the 20 Percent Worst Days and 20 Percent Best 

Days for Five Years (from 2000-2004) in MANE-VU Class I Areas

Class I Area (IMPROVE Monitor) Year

20 Percent Worst 

Days Deciviews 

(dv) 

20 Percent Best 

Days Deciviews 

(dv) 

Acadia National Park (ACAD1) 2000 21.64 8.89 

2001 23.28 8.87 

2002 23.91 8.77 

2003 23.65 8.77 

2004 21.98 8.56 

 Five Year Average 22.89 8.77 

 

Moosehorn National Wildlife Refuge and 

Roosevelt/Campobello International Park 

(MOOS1) 

2000 20.63 8.93 

2001 22.13 9.3 

2002 23.06 9.12 

2003 22.5 9.48 

2004 20.28 8.93 

 Five Year Average 21.72 9.15 

 

Great Gulf Wilderness Area and Presidential 

Range/Dry River Wilderness (GRGU1) 

2000 * * 

2001 23.29 8.26 

2002 24.84 7.77 

2003 21.59 6.94 

2004 21.56 7.68 

 Five Year Average 22.82 7.66 

 

Lye Brook Wilderness Area (LYBR1) 2000 23.45 6.49 

2001 26.32 6.47 

2002 25.52 6.43 

2003 24.02 5.83 

2004 22.91 6.61 

 Five Year Average 24.45 6.36 

 

Brigantine Wilderness Area (BRIG1) 2000 28.95 14.26 

2001 28.38 13.82 

2002 29.31 14.83 

2003 29.79 14.39 

2004 28.59 14.36 

 Five Year Average 29.01 14.33 

*Data does not exist for the Great Gulf Wilderness Area IMPROVE site for the year 2000, however, 

according to the EPA document entitled, Guidance for Tracking Progress Under the Regional Haze Rule, 

states that, “...a minimum of three years of data meeting these completeness requirements is sufficient to 

calculate the 5-year averages within each 5-year period...the three year completeness criterion allows for 

the calculation of baseline conditions at sites with less than five years of data.” 

Source: VIEWS (http://vista.circa.colostate.edu/views/), prepared on 10/16/07 
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5.3 Comparison of Natural and Baseline Conditions

Table 5-3 compares the baseline visibility for the 20 percent worst and the 20 

percent best visibility days based on the five-year average for 2000-2004, natural 

visibility for the 20 percent worst and the 20 percent best visibility days, and the 

difference between baseline and natural visibility conditions for each MANE-VU 

Class I area. These differences provide the beginning and endpoints of the “glide 

path” that indicates the progress that must be made over the term of the Regional 

Haze Program out to 2064. This information is also useful in determining the 

reasonable progress goals (RPGs) that will be established for the term of this SIP 

extending out to 2018, as well as the control measures that contributing states like 

New York will need to implement to meet these goals. 

Reasonable progress goals are discussed in detail in Section 9 of this SIP.

Table 5-3 - Summary of Baseline Visibility and Natural Conditions for the 20 

Percent Worst and 20 Percent Best Visibility Days 

Class I Area 

 

2000-2004 

Baseline (dv) 

Natural 

Conditions (dv) Difference (dv) 

Worst 

20% 

Best 

20% 

Worst 

 20% 

Best 

20% 

Worst 

 20% 

Best 

20% 

Acadia National Park 22.89 8.77 12.43 4.66 10.46 4.11 

Moosehorn National Wildlife 

Refuge 21.72 9.15 12.01 5.01 9.71 4.14 

Roosevelt/Campobello 

International Park 21.72 9.15 12.01 5.01 9.71 4.14 

Great Gulf Wilderness Area 22.82 7.66 11.99 3.73 10.83 3.93 

Presidential Range/Dry River 

Wilderness 22.82 7.66 11.99 3.73 10.83 3.93 

Lye Brook Wilderness Area 24.45 6.36 11.73 2.79 12.72 3.57 

Brigantine Wilderness Area 29.01 14.33 12.24 5.51 16.77 8.82 

Source: VIEWS (http://vista.cira.colostate.edu/views/) prepared on 6/22/2007