NEPA--Environmental Assessment

project design criteria. In addition, the areas with mapped overlap between bighorn sheep summer
range and domestic sheep where the potential for contact between bighorn and domestic sheep is
thought to be low under Alternative 2 (Gladstone and Flume allotments) would remain low under
Alternative 3.
Under Alternative 3, the four active allotments with areas of mapped overlap between domestic
sheep and bighorn sheep summer range (Picayne/Mineral Point, Engine Creek/Deer Creek, Eureka,
and Gladstone allotments) would remain open to sheep grazing. However, the area with mapped
overlap would be significantly reduced under Alternative 3 (reduced by 83% compared to
Alternative 2. See Figures 1-5 and 3-1), and, the application of design criteria under Alternative 3
would, in combination, substantially reduce the potential for contact between domestic sheep and
bighorn sheep, thereby addressing one of the project’s need for change. Because the potential for
contact between domestic sheep and wild sheep would be reduced from High to Moderate in these
four active allotments, the project’s desired conditions for bighorn sheep would be met. The areas
with High Risk for physical contact between domestic sheep and bighorn sheep under Alternative 2
would all be reduced to Moderate Risk under Alternative 3.
The eighth and final area of mapped overlap between domestic sheep and bighorn sheep summer
range, in the southeast corner of the Flume Allotment, would remain a Low potential for contact
between domestic sheep and bighorn sheep due to habitat conditions and remaining vacant to
grazing. If this allotment were restocked in the future the potential for contact between domestic
sheep and wild sheep would be expected to remain Low because of its geographic location and
habitat conditions.
Similar to Alternative 2, selection of Alternative 3 would be expected to have some positive effects
on forage conditions for bighorn sheep. Selecting Alternative 3 would maintain the continued
gradual long term improvement in forage habitat conditions for bighorn sheep that has occurred for
the past 70+ years, but probably at a slower rate than would have occurred under Alternative 1.
Forage habitat conditions for bighorn sheep would be expected to continue their long term gradual
improvement under Alternative 3 because there has been a continued long term decline in the
number of domestic sheep grazed in the Silverton Landscape. There has been a 49% decline in the
number of domestic sheep grazed in the Silverton Landscape over the past 40 years, and a 95%
decline in the number of sheep grazing on the San Juan National Forest over the past 70 years. In
addition, the amount of the Silverton Landscape open to grazing under Alternative 3 would be
substantially reduced compared to Alternative 2. Therefore selecting Alternative 3 would reduce the
amount of area where forage overlap between domestic and bighorn sheep could potentially occur,
and as the number of domestic sheep on the landscape has declined, so too has the risk for direct
physical contact between domestic and bighorn sheep and the subsequent potential for disease
transmission has also declined.
Even if numbers of domestic sheep remain relatively stable over the next few (5+) years, a continued
gradual improvement in bighorn sheep forage conditions and white-tailed ptarmigan summer/fall
habitat areas would be expected under Alternative 3. This is because at current domestic sheep
stocking levels, the observed gradual improvement in alpine plant communities is expected to
continue, and the application of project design criteria and adaptive management practices would
further reduce affects from domestic sheep grazing.
Selecting Alternative 3 would be beneficial for white-tailed ptarmigan, although less beneficial than
selecting Alternative 1, but more beneficial than selecting Alternative 2. The few localized areas
currently affected by sheep grazing would continue to be affected, such as near the alpine/spruce-fir
interface, moist alpine areas adjacent to riparian zones and wet meadows, and upland willow stands
in alpine basins and on ridgelines. Although more rapid improvement in habitat conditions for
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