Hercules-Glades Wilderness

Index

Introduction

Hercules Glades Wilderness, 60 miles southeast of Springfield, consists of open grassland, forested knobs, steep rocky hillsides, narrow drainages, and limestone rock outcroppings. There are three high knobs that stand out from the outer high ridges: Upper and Lower Pilot Knobs, and Coy Bald. From the late 1800's to the 1950's, any area not fenced was considered 'open range' and the glades were heavily grazed by large numbers of horses, cattle, and hogs. Today, cattle-grazing is still permitted within the area. The Ozark climate is mild enough to make visits possible throughout the year. Peak use seasons are spring and fall. Hercules Glades contains limited open-water sources and only portions of Long and Cane Creeks contain water year round.

The Hercules-Glades Wilderness was designated wilderness by the United States Congress in 1976. It was then designated as Class I air quality under the Clean Air Act Amendments of 1977, and now has a total of 11,909 acres.

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Air Quality Related Values

Scenery

The scenic beauty of the Hercules Glades Wilderness is unique in the Ozark Region of south Missouri. The rugged landscape is characterized by high knobs, locally known as balds, which offer a spectacular view of the rugged landscape, and contrasting vegetative communities featuring both a tall grass prairie and a forested landscape. Visitors to the wilderness can, with a short hike, experience panoramic views and visual contrasts between the forest and tall grass-prairie vegetative communities from either or both of the twin Pilot Knobs, two high balds from which the entire wilderness area can be viewed. The most heavily visited spot in the wilderness is a waterfall on Long Creek.

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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) 261 111 131 27 192 55
Haze Index (dv) 4.69 12.84 11.3 26.75 7.57 19.7

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Water Quality

Long Creek, which flows through the center of the wilderness, is an intermittent stream but has pools of water throughout the year. The entire watershed of Long Creek is contained in the Wilderness. Moderate rainfall is sufficient for water to flow swiftly down Long Creek over dolomitic-limestone boulders and natural steps, giving the creek an appearance of having thousands of small waterfalls. Tributaries to Long Creek are the numerous upland waterways or hollows which, due to the high runoff potential of the shallow soils, also become swiftly flowing streams during rainstorms. The chemistry of the water is dominated by calcium and magnesium bicarbonates, and pH is slightly alkaline. Nutrient levels are low and, in the absence of storm water runoff, stream waters are remarkably clear. Fish species include largemouth and smallmouthed bass, rock bass, green sunfish, longear sunfish, and numerous species of suckers and minnows capable of existing in an intermittent stream.

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Floral Diversity

Vegetation within the Hercules Glades Wilderness is a study in contrasts, and perhaps its most outstanding natural feature. At one extreme is the oak-hickory forest. At the other are extensive areas of open, tall grass-prairie vegetation featuring flowers, grasses, and forbs.

The thinnest soils have a prairie vegetation intermingled with eastern redcedar, smoketree, winged elm, aromatic sumac, chinkapin, and post oak. As the soils become deeper, larger trees dominate with a mixture of chinkapin oak, white ash, post oak, blackjack oak, and eastern red cedar. The glade areas support grass species common to the great prairies: big and little bluestem, Indian grass, prairie dropseed, side oats grama, and switchgrass are common. Associated forbs include black-eyed susan, several species of coneflower, shooting star, Missouri primrose, and prairie clover. Rare, threatened and endangered plants such as ciliate bluestar, blazing star, stonecrop, and treleases larkspur also are found on the glades.

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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 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.

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AQRV Type: WATER
Sensitive Receptor Sensitive Receptor Indicator Thresholds
Aquatic Organisms Chemistry Effective sulfur deposition may significantly impact aquatic organisms at levels above 11 kg/ha/yr. Total sulfur plus 20% of nitrogen deposition at levels exceeding 14 kg/ha/yr may cause ANC loss that would impact aquatic organisms.
Perennial Streams Chronic Acid Neutralizing Capacity To maintain healthy biological functioning in perennial streams, the chronic acid neutralizing capacity must be >= 25 ueq/l. Acid neutralizing capacity below 10 ueq/L (the red line) are expected to cause adverse impacts.
Perennial Streams Episodic Acid Neutralizing Capacity To maintain healthy biological functioning in perennial streams, the episodic acid neutralizing capacity must be >= 0 ueq/l.

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Pollutant Exposure Concern Thresholds
Pollutant Exposures Level Name Thresholds
S+20%N Red Line Total sulfur plus 20% of nitrogen deposition at levels exceeding 14 kg/ha/yr may cause ANC loss that would impact aquatic organisms.
Sulfur DEPOSITION Total sulfur deposition at levels below 30 kg/ha/yr is not expected to significantly impact aquatic organisms.
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):Missouri
County(s):Taney
Forest Service Administrative Unit(s):Eastern Region (Region 9) -- Mark Twain National Forest
Size:12,314 acres
Elevation Range:760 - 1,360 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: 09/06/13