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Sierra Ancha Wilderness


General Information

Image of Sierra Ancha Wilderness

State(s): Arizona

County(s): Gila

Forest Service Administrative Unit(s):
Southwest Region (Region 3) -- Tonto National Forest

Size: 20850 acres

Elevation Range: 5,200 - 8,000 feet

Image(s): http://www.wilderness.net/images/

Detailed wilderness information: http://www.wilderness.net

GIS Map/Official Boundary: http://www.wilderness.net/NWPS/

Webcam(s): Sierra Ancha (Gallery)

Data:

Contacts

Documents

Resource Concern Thresholds

AQRV Type: VISIBILITY
Sensitive Receptor Sensitive Receptor Indicator Thresholds
Natural Visibilty 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.
Natural Visibilty 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.
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.

AQRV Type: WATER
Sensitive Receptor Sensitive Receptor Indicator Thresholds
Headwater Systems Acid Neutralizing Capacity For headwater systems that have a baseline Acid Neutralizing Capacity of >400 ueq/l, an ANC no lower than 400 ueq/l is acceptable.
Headwater Systems Acid Neutralizing Capacity For headwater systems that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, an ANC no lower than 200 ueq/l is acceptable.
Headwater Systems Acid Neutralizing Capacity For headwater systems that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, no more than a 10% decrease in ANC is acceptable.
Headwater Systems Acid Neutralizing Capacity For headwater systems that have a baseline Acid Neutralizing Capacity of >400 ueq/l, no more than a 15% decrease in ANC is acceptable.
Headwater Systems Acid Neutralizing Capacity For headwater systems that have a baseline Acid Neutralizing Capacity of <200 ueq/l, no decrease in ANC is acceptable.
Headwater Systems Base Cations For headwater systems that are in compliance with state water quality standards for base cations, a base cation decrease of > 0.25 deviations is unacceptable.
Headwater Systems Base Cations For headwater systems that are in violation of state water quality standards for base cations, no decrease in base cations is acceptable.
Headwater Systems Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For headwater systems that are in violation of state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), no increase in metal concentrations is acceptable.
Headwater Systems Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For headwater systems that are in compliance with state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), a metal concentration increase of >0.25 deviations is unacceptable.
Headwater Systems Nitrate For headwater systems that are in violation of state water quality standards for nitrate levels, no increase in nitrates is acceptable.
Headwater Systems Nitrate For headwater systems that are in compliance with state water quality standards for nitrate levels, a nitrate increase of >0.25 deviations is unacceptable.
Headwater Systems Total Dissolved Nitrogen For headwater systems that are nitrogen-limited or co-limited, no change in total dissolved nitrogen is acceptable.
Headwater Systems pH For headwater systems that have a baseline pH of 6.5-7.0, no more than a 0.1 decrease in pH is acceptable.
Headwater Systems pH For headwater systems that have a baseline pH of >7.0, no more than a 0.3 decrease in pH is acceptable.
Headwater Systems pH For headwater systems that have a baseline pH of 6.5-7.0, a pH no lower than 6.5 is acceptable.
Headwater Systems pH For headwater systems that have a baseline pH of >7.0, a pH no lower than 6.7 is acceptable.
Perennial Streams Acid Neutralizing Capacity For perennial streams that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, an ANC no lower than 200 ueq/l is acceptable.
Perennial Streams Acid Neutralizing Capacity For perennial streams that have a baseline Acid Neutralizing Capacity of >400 ueq/l, an ANC no lower than 400 ueq/l is acceptable.
Perennial Streams Acid Neutralizing Capacity For perennial streams that have a baseline Acid Neutralizing Capacity of <200 ueq/l, no decrease in ANC is acceptable.
Perennial Streams Acid Neutralizing Capacity For perennial streams that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, no more than a 10% decrease in ANC is acceptable.
Perennial Streams Acid Neutralizing Capacity For perennial streams that have a baseline Acid Neutralizing Capacity of >400 ueq/l, no more than a 15% decrease in ANC is acceptable.
Perennial Streams Base Cations For perennial streams that are in violation of state water quality standards for base cations, no decrease in base cations is acceptable.
Perennial Streams Base Cations For perennial streams that are in compliance with state water quality standards for base cations, a base cation decrease of > 0.25 deviations is unacceptable.
Perennial Streams Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For perennial streams that are in compliance with state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), a metal concentration increase of >0.25 deviations is unacceptable.
Perennial Streams Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For perennial streams that are in violation of state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), no increase in metal concentrations is acceptable.
Perennial Streams Nitrate For perennial streams that are in violation of state water quality standards for nitrate levels, no increase in nitrates is acceptable.
Perennial Streams Nitrate For perennial streams that are in compliance with state water quality standards for nitrate levels, a nitrate increase of >0.25 deviations is unacceptable.
Perennial Streams Total Dissolved Nitrogen For perennial streams that are nitrogen-limited or co-limited, no increase in total dissolved nitrogen is acceptable.
Perennial Streams pH For perennial streams that have a baseline pH of 6.5-7.0, a pH no lower than 6.5 is acceptable.
Perennial Streams pH For perennial streams that have a baseline pH of >7.0, no more than a 0.3 decrease in pH is acceptable.
Perennial Streams pH For perennial streams that have a baseline pH of >7.0, a pH no lower than 6.7 is acceptable.
Perennial Streams pH For perennial streams that have a baseline pH of 6.5-7.0, no more than a 0.1 decrease in pH is acceptable.
Temporary Waters Acid Neutralizing Capacity For temporary waters that have a baseline Acid Neutralizing Capacity of <200 ueq/l, no decrease in ANC is acceptable.
Temporary Waters Acid Neutralizing Capacity For temporary waters that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, no more than a 10% decrease in ANC is acceptable.
Temporary Waters Acid Neutralizing Capacity For temporary waters that have a baseline Acid Neutralizing Capacity of 200-400 ueq/l, an ANC no lower than 200 ueq/l is acceptable.
Temporary Waters Acid Neutralizing Capacity For temporary waters that have a baseline Acid Neutralizing Capacity of >400 ueq/l, an ANC no lower than 400 ueq/l is acceptable.
Temporary Waters Base Cations For temporary waters that are in violation of state water quality standards for base cations, no decrease in base cations is acceptable.
Temporary Waters Base Cations For temporary waters that are in compliance with state water quality standards for base cations, a base cation decrease of >0.25 deviations is unacceptable.
Temporary Waters Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For temporary waters that are in violation of state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), no increase in metal concentrations is acceptable.
Temporary Waters Metal Concentration (Cu, Pb, As, Se, Zn, Ni) For temporary waters that are in compliance with state water quality standards for metal concentration (Pb, Zn, Hg, As, Cd, Se, Cu), a metal concentration increase of >0.25 deviations is unacceptable.
Temporary Waters Nitrate For temporary waters that are in compliance with state water quality standards for nitrate levels, a nitrate increase of > 0.25 deviations is unacceptable.
Temporary Waters Nitrate For temporary waters that are in violation of state water quality standards for nitrate levels, no increase in nitrates is acceptable.
Temporary Waters Total Dissolved Nitrogen For temporary waters that are nitrogen-limited or co-limited, no increase in total dissolved nitrogen is acceptable.
Temporary Waters pH For temporary waters that have a baseline pH of 6.5-7.0, a pH no lower than 6.5 is acceptable.
Temporary Waters pH For temporary waters that have a baseline pH of >7.0, no more than a 0.3 decrease in pH is acceptable.
Temporary Waters pH For temporary waters that have a baseline pH of >7.0, a pH no lower than 6.7 is acceptable.
Temporary Waters pH For temporary waters that have a baseline pH of 6.5-7.0, no more than a 0.1 decrease in pH is acceptable.
Pollutant Exposure Concern Thresholds
Pollutant Exposures Level Name Thresholds
Nitrogen EXCEEDANCE The Deposition Analysis Threshold for nitrogen deposition is 0.010 kg/ha/yr. Below this, estimated impacts from a source greater than 50km from a FLM Class I Area are considered negligible.
Q (Sum of SO2+NOx+PM10+H2SO4) QOverD For new or modified sources locating greater than 50 km from a Class I area, its impacts will be considered negligible with respect to Class I AQRVs if its total SO2, NOx, PM10, and H2SO4 annual emissions in tons/yr, based on 24-hr maximum allowable emissions, divided by the distance (km ) from the Class I area (Q/D) is 10 or less. For sources operating less than a year, the emissions must be adjusted to reflect what the emissions would be if the source operated year-round.
Sulfur EXCEEDANCE The Deposition Analysis Threshold for sulfur deposition is 0.005 kg/ha/yr. Below this, estimated impacts from a source greater than 50km from a FLM Class I Area are considered negligible.
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.
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.
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.
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.
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.
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.

Natural Background Visibility

Site Specific Rayleigh scattering coefficient: 10 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) 319 211 202 100 262 149
Haze Index (dv) 2.03 6.16 6.59 13.67 4.02 9.67
For more information on these numbers, click here.