NEPA--Environmental Assessment

Similar to Alternative 2, selecting Alternative 3 would have both positive and negative effects for
sensitive species. Selecting Alternative 3 would have beneficial effects for sensitive species,
compared to Alternative 2, because application of adaptive management strategies and project
design criteria should result in more rapid improvements in habitat conditions in some localized
areas where sheep grazing impacts are currently occurring. Also similar to Alternative 2, Alternative
3 would have negative effects for sensitive species, compared to Alternative 1, because a few
localized areas would continue to be affected by sheep grazing activities, such as near the
alpine/spruce-fir interface, moist alpine areas adjacent to riparian zones or wet meadows, and upland
willow stands in alpine basins.
Selecting Alternative 3 would be more beneficial for sensitive species than selecting Alternative 2,
but would be less beneficial than selecting Alternative 1. This is because improvement in habitat
conditions would probably occur over a longer time frame than under Alternative 1, but a shorter
time frame than Alternative 2 due to the application of adaptive management strategies and project
design criteria. In general, habitat conditions for sensitive species are expected to continue to
gradually improve in most areas under Alternative 3, but would continue to be impacted in a few
localized areas.
Compared to Alternative 2, the application of adaptive management strategies and project design
criteria under Alternative 3 should result in more rapid improvements in habitat conditions in some
localized areas where sheep grazing impacts are currently occurring because adaptive management
strategies would not be fully applied under Alternative 2. Although more rapid improvement in
habitat conditions for bighorn sheep, white-tailed ptarmigan and wolverine is expected under
Alternative 3 than under Alternative 2, improvements in habitat conditions as a result of the adaptive
management approach are likely to be too small to affect populations or the total amount of habitat
available for these species in the Silverton Landscape.
Selecting Alternative 3 would be much more beneficial for bighorn sheep than selecting Alternative
2, although less so than selecting Alternative 1. Alternative 3 would be less beneficial for bighorn
sheep than Alternative 1 because five allotments with areas of mapped overlap between domestic
sheep and bighorn sheep summer range (Picayne/Mineral Point, Engine Creek/Deer Creek, Eureka,
and Gladstone active allotments, and Flume vacant allotment) would remain open to sheep grazing
under Alternative 3. However, the potential for contact between domestic sheep and bighorn sheep
in these five allotments with areas of mapped overlap would be reduced from High to Moderate (4
active allotments) or Low (1 vacant allotment).
Alternative 3 would be much more beneficial for bighorn sheep than Alternative 2. This is because
three vacant allotments would remain available for sheep grazing under Alternative 2 (Little
Molas/West Needles Allotment, Needles Mountains Allotment, and Minnie Gulch Allotment) but
would be permanently closed to grazing under Alternative 3 (Figure 3-1). These three allotments
would have High Risk for contact if they were stocked with domestic sheep under Alternative 2, but
would have Low Risk for contact if closed under Alternative 3. For this reason, the potential for
physical contact between domestic sheep and bighorn sheep in these 3 allotments would be reduced
from High to Low, and the project’s desired condition for bighorn sheep would be met in these three
allotments.
As a result of closing these three allotments, under Alternative 3 the amount of mapped overlap
between areas suitable for domestic sheep and mapped bighorn sheep summer range in the Silverton
Landscape would be reduced from about 10,285 acres (Alternative 2) to about 1,756 acres
(Alternative 3). The areas of mapped overlap between bighorn sheep and domestic sheep ranges
where risk of physical contact between bighorn and domestic sheep is thought to be High would all
be reduced to Moderate Risk with the modification of allotment boundaries and the application of
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