NEPA--Environmental Assessment

natural barrier to bighorn sheep movement. There have been no recent sightings of bighorn sheep in
the mapped overlap area. This allotment has been vacant since 1989. Under Alternative 2, if the
Flume Allotment were to be restocked, the lack of suitable habitat for domestic sheep or bighorn
sheep in or near the zone of overlap, and the distance from the Animas River canyon (about 3.5
miles) results in a rating of “Low Risk” for contact. Under Alternative 3, the Flume Allotment
would be managed as a forage reserve allotment and grazed by domestic sheep on an irregular basis.
Project design criteria would be applied to the allotment when it was active, and the habitat
conditions described above would result in a “Low Risk” for contact.
Most of the vacant BLM Minnie Gulch Allotment is mapped as overlap with the S33 Pole
Mountain/Upper Lake Fork bighorn sheep herd. There is about 2,536 acres of overlap in the
allotment but only about 319 acres (13%) is suitable domestic sheep grazing range. Formal surveys
conducted in the allotment have failed to detect bighorn sheep but the CDOW continues to receive
reports of bighorn sheep in the gulch during summer. It is thought likely that bighorn sheep reported
in the gulch may be coming from the nearby Crown Mountain or Pole Creek Mountain
subpopulations. This grazing allotment has been vacant since 1983. Under Alternative 2, if the
allotment were to be restocked, the substantial area of overlap between mapped bighorn sheep
summer range, regular reports of bighorn occurrence in the overlap areas, and close proximity to
known bighorn use areas results in a rating of “High Risk” for contact. Under Alternative 3, the
allotment would be closed to domestic sheep grazing and the rating would be “Low Risk” for contact
because domestic sheep would not be permitted in the allotment.
In the active BLM Gladstone Allotment there is a small area in the southern end of the allotment that
overlaps with mapped summer range for the S71 West Needles bighorn sheep herd. Under current
management, there is about 320 acres of overlap, with only about 11 acres (3%) being suitable
domestic sheep grazing range. This area of mapped overlap is well removed from areas actually
used by domestic sheep. The area of overlap is immediately adjacent to the town of Silverton. The
area bighorns would have to pass through, and much of the overlap area itself, is consistent with the
description in Schommer and Woolever (2001) of a continuous forest that could serve as a natural
barrier to bighorn sheep movement. Under Alternative 2, the permittee does not use the south end of
the allotment where the zone of overlap occurs due to dense forest cover and lack of forage. For this
reason, the rating for this area is “Low Risk” for contact. Under Alternative 3, the allotment would
be closed to domestic sheep grazing in the south end of the allotment resulting in a “Low Risk” for
contact.
Most of the active BLM Picayne/Mineral Point Allotment is mapped as overlap with the S33 Pole
Mountain/Upper Lake Fork bighorn sheep herd. There is about 2,158 acres of mapped overlap in
this allotment. Within this area, about 378 acres (18%) is suitable domestic sheep grazing range.
Extensive surveys for bighorn sheep have been conducted in the area of overlap over the past four
summer seasons and no bighorn sheep have been detected or reported by the domestic sheep
permittee. Immediately across the Animas River canyon however, surveys have regularly detected
small bands of bighorn sheep using Grouse and Burns Gulches. The bighorn use areas are within ¼
mile of a route permitted for domestic sheep trailing into and out of the allotment under Alternative
2. The allotment is heavily used by the public for motorized recreation with an extensive network of
heavily traveled 4x4 roads and no bighorn sheep have been reported in the area of overlap.
Although much of the allotment is steep, there is little rocky terrain or other structures preferred by
bighorn sheep as escape cover.
Under Alternative 2, the close proximity (about 1 mile) of domestic sheep and bighorn sheep in the
Grouse and Burns Gulch areas results in a rating of “High Risk” for contact in the Picayne/Mineral
Point Allotment. Under Alternative 3, the application of project design criteria, use of the adjusted
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