NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
Alternative 3 – Moderate
Under Alternative 2, the close proximity of the Eureka corrals and sheep driveway to
bighorn use areas (about 1.5 miles), the proximity of the mapped overlap area to known
bighorn use areas (about 2.0 miles), the close proximity of the north half of the allotment
to mapped bighorn summer range (sharing a common boundary for several miles), and
the expanding nature of the S33 bighorn sheep herd, together result in a rating of “High
Risk” for contact in the Eureka Allotment.
Under Alternative 3, the application of additional herding techniques and project design
criteria described below (Table 3), the lack of domestic sheep use of the area of overlap,
the lack of bighorn occurrences in the allotment or west of the Animas River, the lack of
bighorn preferred habitat components in the allotment, and decades of historic use of the
allotment without evidence of contact with bighorns from S33, together result in a rating
of “Moderate Risk” for contact in the Eureka Allotment.
Maggie Gulch Allotment (BLM, active allotment):
In the active BLM Maggie Gulch Allotment there is no overlap with mapped bighorn sheep
summer range. However, much of the northeast boundary of the allotment adjoins the
southern boundary of mapped summer range for the S33 Pole Mountain/Upper Lake
Fork bighorn sheep herd. This shared common boundary runs along the crest of a
ridgeline that separates Maggie Gulch from Minnie Gulch to the north. The Colorado
Division of Wildlife has received occasional reports of bighorn sheep along the crest of this
ridge. The upper half of Maggie Gulch is where most of the domestic sheep grazing occurs
in this allotment. Most of the allotment is relatively broad rolling alpine plateaus and
basins with relatively little rocky terrain or talus slopes for bighorn escape cover.
Surveys for bighorn sheep were conducted by BLM employees in summer 2008 and no
bighorn sheep were detected in the allotment. The domestic sheep permittee has reported
no sightings of bighorn sheep in the allotment. Maggie Gulch is a popular area for
summer recreation with good road access but no bighorn sheep have been reported to
CDOW.
Domestic sheep have been grazed in the Maggie Gulch Allotment since prior to the Second
World War. Stocking records since 1953 indicate similar numbers of sheep were grazed
throughout this period to what is currently permitted.
Summary of Risk Rating for Maggie Gulch Allotment:
Risk Rating: Alternative 2 – Moderate
Alternative 3 – Moderate
Under Alternative 2, the close proximity of the north half of the allotment to mapped
bighorn summer range (sharing a common boundary for several miles), and the
expanding nature of the S33 bighorn sheep herd, together result in a rating of “Moderate
Risk” for contact in the Maggie Gulch Allotment.
Under Alternative 3, the application of additional herding techniques and project design
criteria described below (Table 3), the lack of bighorn occurrences in the allotment, the
lack of bighorn preferred habitat components in grazed portions of allotment, and decades
of historic use of the allotment without evidence of contact with bighorns from S33,
together result in a rating of “Moderate Risk” for contact in the Maggie Gulch Allotment.
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