NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
through heavily forested steep north facing hillsides to access this area. The area
bighorns would have to pass through, and much of the area of overlap itself, is consistent
with the description provided by Schommer and Woolever (2001) of a continuous forest
that could serve as a natural barrier to bighorn sheep movement. The area of overlap does
have some rock outcrops and talus slopes that provide typical bighorn sheep escape
cover. There have been no sightings of bighorn sheep in the area, and it is about 4.5 miles
down the Animas River canyon to areas known to be used by bighorn sheep.
Under current management, the domestic sheep permittee does not use the southern
portion of the Gladstone Allotment, including all of the area of mapped overlap. Under
Alternative 3, domestic sheep would not be permitted to graze in the Cement Creek
drainage south of Hancock Gulch on either side of Cement Creek. Hancock Gulch is
about 1.0 mile north of the boundary of the summer range area for S71. In the adjacent
Forest Service Red Mountain Allotment, domestic sheep are not permitted to graze south
of Ohio Peak, about 2.5 miles to the north and west of mapped bighorn summer range.
Summary of Risk Rating for Gladstone Allotment:
Risk Rating: Alternative 2 – Low
Alternative 3 – Low
Under Alternative 2, the permittee does not use the extreme south end of the Gladstone
Allotment where the zone of overlap occurs due to dense forest cover and lack of suitable
domestic sheep forage. The lack of suitable forage areas for bighorn sheep in the zone of
overlap, the distance from bighorn use areas in the Animas River canyon (about 4.5
miles), and the town of Silverton acting as a barrier to bighorn movement together result
in a rating of “Low Risk” for contact.
Under Alternative 3, the Gladstone Allotment would be closed to grazing south of Hancock
Gulch and the adjacent Red Mountain Allotment would be closed to grazing south of Ohio
Peak. Project design criteria would be applied to sheep grazing the remainder of the
Gladstone allotment, and the habitat conditions described above in the area of mapped
overlap, would together result in a rating of “Low Risk” for contact.
Picayne/Mineral Point Allotment (BLM, active allotment):
Under current management, there is about 2,158 acres of overlap in this active BLM
allotment with mapped summer range for the S33 Pole Mountain/Upper Lake Fork
bighorn sheep herd. Within this area, about 378 acres (18%) is suitable domestic sheep
grazing range.
BLM grazing records for this allotment date back to 1967 but domestic sheep have been
grazed here since prior to the Second World War. Prior to 1990, the stocking rate of this
allotment was about twice what it is currently. Most of the south half of the allotment
provides suitable domestic sheep grazing and there is good access to most of the
allotment by 4WD roads.
The area of overlap with bighorn summer range covers nearly the entire southern half of
the allotment south of the ghost town of Animas Forks. Although much of the allotment is
steep, there is little rocky terrain or talus slopes for bighorn escape cover west of the
Animas River canyon. Most of the terrain in the south half of the allotment is alpine
meadows bisected by high ridges and steep slopes and canyons traversing higher alpine
peaks.
D-17