NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
The second area of overlap in the Engine Creek/Deer Creek Allotment with S71 summer
range is a linear area that parallels U.S. Highway 550 to the west of the highway near
Molas Pass in an area burned by the Lime Creek fire in the late 1800’s. This area is
mostly gently rolling benches across non-forested areas with few rock outcrops or other
structures that provide typical bighorn sheep escape cover. It is a popular recreation area
and in close visibility from a heavily traveled highway. There have been no sightings of
bighorn sheep in this area. It is about 2 air miles from the rim of the Animas River canyon
across a mixture of dense mature spruce-fir forest and subalpine meadows.
Summary of Risk Rating for Engine Creek/Deer Creek Allotment:
Risk Rating: Alternative 2 – High
Alternative 3 – Moderate
Under Alternative 2, the presence of the Lime Creek corrals and the need to trail domestic
sheep through mapped bighorn sheep summer range, followed by the close proximity
(about 1 mile) of domestic sheep and 2009 bighorn sheep sightings near the Lime Creek
corrals, combine to result in a rating of “High Risk” for contact. Under Alternative 2 the
Lime Creek corrals are accessed twice per season by the domestic sheep band, increasing
the potential for contact with bighorn sheep, compared to Alternative 3. Domestic sheep
herding techniques however typically bring the sheep rapidly past where the 2009
bighorn sightings occurred and through the zone of overlap with the S71 summer range,
providing some mitigation of the “High Risk” rating.
Under Alternative 3, the application of project design criteria, use of the Lime Creek
corrals only once per season, and modification of the boundary of the Engine Creek/Deer
Creek Allotment shifting domestic sheep presence to areas of overlap that have lower
habitat value for bighorn sheep, combine to result in a rating of “Moderate Risk” for
contact.
Little Molas/West Needles Allotment (FS, vacant allotment):
Under current management, there is about 20,705 acres of overlap in the allotment with
mapped summer range of the S71 West Needles bighorn sheep herd. Within this area,
about 7,556 acres (36%) is suitable domestic sheep grazing range. Of the suitable grazing
range, about 6,434 acres are on NFS lands and 1,122 acres are on BLM lands. Under
Alternative 3, about 19,891 acres of overlap area would be closed to grazing. The
remaining 813 acres of overlap with S71 summer range would be added into the active
Engine Creek/Deer Creek Allotment under a boundary adjustment designed to allow
closure of the remainder of the Little Molas/West Needles Allotment.
The southern portion of this allotment overlaps with substantial areas of mapped bighorn
sheep summer concentration areas on the north end of the West Needle Mountains, and
most of the remainder of the allotment overlaps with mapped summer range. The mapped
summer concentration area is used throughout the summer season by bighorn sheep, as
are portions of the mapped summer range in central portions of the allotment. Under
Alternative 2, the Little Molas/West Needles Allotment east of U.S. Highway 550 would
remain vacant and therefore available for restocking administratively at any time. Much of
the areas of mapped overlap also provide substantial areas of suitable domestic sheep
grazing opportunities, although the allotment has been vacant since 1999.
Under Alternative 3 the Little Molas/West Needles Allotment would be closed to domestic
sheep grazing. However, under Alternative 3, the boundary of the allotment would be
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