NEPA--Environmental Assessment

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of 1,272 acres of mineralized soil from grazing. The largest amount of mineralized still likely to be grazed are in Prospect Gulch, and the proposed action intends to limit the number of days sheep are allowed in Prospect Gulch. Compared to the mineral soil exposed to erosion from historic mining activities, any small increase due to sheep grazing is expected to be minimal. Gladstone Allotment was observed during rainstorms in 2008, and found that trailing and grazing from sheep that day and the previous day was producing no sediment-laden runoff, but water in roadside ditches below mine dumps was carrying significant sediment load. CUMULATIVE IMPACTS The largest impact to watersheds and water quality in this analysis area is past mining, milling and road building. This is described under the affected environment (above). Other activities that can negatively impact watersheds and water quality include: private land development (mining, summer homes, ski area, etc.), new road construction, road and trail use, road maintenance, and recreational pack stock use. Past and ongoing mine reclamation projects undertaken by members of the Animas River Stakeholders Group are a beneficial impact to water quality. The impact from domestic sheep grazing under Alternative 3 (adaptive management) is expected to be inconsequential in the context of cumulative effects. Vegetation & Soils________________________________ AFFECTED ENVIRONMENT The Silverton project area occurs in a mountainous landscape dominated by alpine vegetation and spruce-fir forests. Mixed conifer forests, aspen forests, and mountain grasslands also occur to a limited extent, and riparian areas and wetlands are scattered throughout the area. Most of the project area is associated with volcanic deposits of volcaniclastic and near-source facies, volcanic deposits of the Henson and Burns geologic formation, and sedimentary deposits of the Cutler, Rico, Hermosa, and Molas geologic formations. This section focuses on the vegetation and soils of the alpine zone (the alpine major vegetation type) within the project area, since this is the area most affected by sheep grazing. Vegetation and soils of the other vegetation types of the project area display no effects or only minor adverse effects from sheep grazing. The alpine zone on San Juan Public Lands occurs at elevations above about 11,500 feet where the growing season is short, the winters are long, the winds are high, and the sun is intense. The alpine landscape was shaped by geologic events and glaciation, and is both steep and rugged, and gentle and smooth. Rock outcrop and talus slopes are common. Soils are shallow and rocky on steep slopes and exposed ridges, and deeper, less rocky, and more productive on other sites. There is tremendous diversity of species and vegetation types within the alpine zone and plant communities often change quickly and abruptly over short distances, due to small-scale topographic changes that exert a significant influence on snow and moisture conditions and the associated vegetation. Alpine rangelands have been used for sheep grazing since the mid 1800s. Prior to government control, sheep were herded in tightly grouped bands and usually bedded in the same location for several nights in a row, which resulted in large forage losses and in soil damage (Paulsen 1960). Some sites in the project area still display these historic effects (ID team observation 2008). Currently sheep (including the ones in the project area) are herded loosely but will aggregate in large groups when resting or drinking and then gradually split up into smaller groups as they graze away 55
from water or bedgrounds (Arnold and Dudzinski 1978). Sheep are considered “intermediate feeders” meaning they utilize graminoids, forbs, and shrubs and have the ability to adjust their feeding habits to whatever is available, but they generally prefer forbs (Vallentine 1990, Johnson 1962, Paulsen 1960). Leaves are the most readily grazed portions of most plants with sheep averaging 40% utilization of leaves compared to 9% for stems (Cook et al. 1948). Sheep consumption and trampling of the flowers of plants may affect seed production and may reduce the amount of flowers available for wildflower viewing, but in most cases will not cause mortality to the affected plants. Vegetation Types Alpine vegetation types at the subclass level include fellfield, turf, upland willow, dwarf willow, wetland willow, herbaceous wetland, and krummholtz (Baker 1983, Paulsen 1960, Dick-Peddie 1993, Thilenius 1975). Currently most of these types display high native species diversity, adequate ground cover, and productive soils. Some sites reflect effects associated with long-term domestic sheep grazing including sheep trailing along livestock driveways and across mountain slopes, and trampling at sheep bedgrounds. The fellfield type is an upland type that occurs on harsh, wind-swept sites with shallow, rocky, moderately well to well-drained soils that classify predominantly as Lithic Dystrochrepts, loamyskeletal (Pannell 2006, Redders personal observation 2008). Surface rock (gravel and cobble) and patches of bare soil are common. It is dominated by short cushion plants (forbs) and displays a relatively low canopy cover. In this project area, the fellfield type commonly occurs as small patches mixed within the matrix of the alpine avens (Acomastylis rossi) turf type. Common species of the fellfield type include Silene acaulis, Paronychia pulvinata, Erigeron vagus, Amerosedum lanceolatum, Ivesia gordonii, Trifolium nanum, Lidia obtusiloba, and Phlox condensata. Sheep foraging in this type is minor as the dominant plants that occur there are not preferred forage species. Current species composition and distribution in this type are likely similar to conditions found during the reference period. Effects from sheep trailing and trampling (soil displacement and sheet erosion) however can be significant in the fragile soils of this vegetation type. The dwarf willow type is an upland type that is dominated by both snow willow and alpine willow (Salix nivales and Salix petrophila) small, prostrate-growing plants that occur in separate or mixed patches. The type occurs on relatively dry sites on moderately well to well-drained, often shallow soils. Soils classify predominantly as Lithic Dystrochrepts, loamy-skeletal (Pannell 2006, Redders personal observation 2008). Phlox condensata, Amerosedum lanceolatum, Acomastylis rossi and lichens are common associates in the dwarf willow vegetation type. Sheep foraging in the dwarf willow type is minor as the dominant plants that occur there are not preferred forage species. Current species composition and distribution in this type are likely similar to conditions found during the reference period. The turf type is an upland type that occurs on protected sites away from excessive wind and tends to have relatively deep (greater than 20 inches to bedrock), moist, moderately well to somewhat poorlydrained, and well-developed soils that classify predominantly as Typic Dystrochrepts, loamy-skeletal (Pannell 2006, Redders personal observation 2008). It is dominated by forbs and graminoids, and usually displays a relatively high canopy cover. Within the turf type of this project area a number of plant community types are present including a Kobresia myosuroides type that occurs on relatively dry sites, a Parry rush (Juncus parryi) type, and an alpine avens (Acomastylis rossi) type, the latter being the most common. The alpine avens type, where alpine avens is the dominant or codominant species, is quite variable ranging from a moist phase where Caltha leptosepala is common to a dry phase where cushion plants are common. On less productive sites and sites where natural erosion is occurring, which is common in alpine areas including those of this project area, the turf types display 56
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United States Department of Agricul
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Silverton Landscape Grazing Analysi
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These issues led the agency to deve
Page 7 and 8: administered with shared facilities
Page 9 and 10: Engine Creek/Deer Creek Allotment T
Page 11 and 12: Gladstone Allotment This allotment
Page 13 and 14: Gulch. In 1956, the numbers decreas
Page 15 and 16: Figure 1-1. Project Analysis Area 1
Page 17 and 18: Specific Management Emphasis Areas
Page 19 and 20: Livestock Grazing Permits Livestock
Page 21 and 22: Figure 1-3. Management Emphasis Are
Page 23 and 24: Desired Conditions for Bighorn: Red
Page 25 and 26: Figure 1-4. 2008 Data Collection Po
Page 27 and 28: Figure 1-6. Wilderness Overlap 24
Page 29 and 30: Issues ____________________________
Page 31 and 32: CHAPTER 2 - ALTERNATIVES This chapt
Page 33 and 34: Alternative Livestock Bedding 2 3 S
Page 35 and 36: Alternative Noxious Plants/Invasive
Page 37 and 38: Table 2-2. Project Design Criteria
Page 39 and 40: Alternative Minimization of Threat
Page 41 and 42: Alternative 2 - Current Management_
Page 43 and 44: Elk Creek Allot • Do not use the
Page 45 and 46: Figure 2-1. Proposed Action - Avoid
Page 47 and 48: Monitoring for Alternative 3 Monito
Page 49 and 50: • Photographs and Photo-points: P
Page 51 and 52: years in an emergency situation, su
Page 53 and 54: Comparison of Alternatives ________
Page 55 and 56: Water Quality _____________________
Page 57: ENVIRONMENTAL CONSEQUENCES Alternat
Page 61 and 62: 2008). It differs from the wetland
Page 63 and 64: Red Mountain Allotment Yellow toadf
Page 65 and 66: unlikely that any of these species
Page 67 and 68: Recreation Special Use Permits for
Page 69 and 70: livestock management would not chan
Page 71 and 72: Concurrent to this grazing analysis
Page 73 and 74: Alternative 2 Habitat conditions fo
Page 75 and 76: intensity on alpine plants appeared
Page 77 and 78: the other two species due to the co
Page 79 and 80: lack bighorn sheep escape cover. Th
Page 81 and 82: trailing route, and lack of bighorn
Page 83 and 84: Similar to Alternative 2, selecting
Page 85 and 86: ptarmigan is expected under Alterna
Page 87 and 88: CUMULATIVE IMPACTS Global warming i
Page 89 and 90: Wildlife - Management Indicator Spe
Page 91 and 92: and it will not be discussed in det
Page 93 and 94: Selecting Alternative 2 would have
Page 95 and 96: for MIS in the landscape. Wildlife
Page 97 and 98: The alpine tundra group would benef
Page 99 and 100: species of conservation concern as
Page 101 and 102: management options, while others ma
Page 103 and 104: prior to evaluating them for the NR
Page 105 and 106: present state. In general, where un
Page 107 and 108: CHAPTER 4 - CONSULTATION AND COORDI
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APPENDIX B - CITATIONS AND REFERENC
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Martin, K.D., T.J. Schommer, and V.
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Regional Office, Durango, CO. Weste
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Species Habitat Present In the Spec
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Species Mammals (13) Allen’s big-
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MIS Species Preferred Habitat Broug
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Likelihood of Species Status* Prefe
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APPENDIX D - BIGHORN RISK ASSESSMEN
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Silverton Grazing Risk Assessment T
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Silverton Grazing Risk Assessment a
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Silverton Grazing Risk Assessment b
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Silverton Grazing Risk Assessment N
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Silverton Grazing Risk Assessment i
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Silverton Grazing Risk Assessment M
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Silverton Grazing Risk Assessment A
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Silverton Grazing Risk Assessment R
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Silverton Grazing Risk Assessment m
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Silverton Grazing Risk Assessment H
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Silverton Grazing Risk Assessment F
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Silverton Grazing Risk Assessment F
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NEPA--Environmental Assessment

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