NEPA--Environmental Assessment

Silverton Grazing Risk Assessment
Under Alternative 3, the preferred alternative, the amount of overlap between active and
vacant domestic sheep allotments and mapped bighorn sheep summer range in the
Silverton Landscape would be reduced by 83%, primarily by closing allotments that have
remained vacant for the past decade or more.
Of the 7,105 acres of overlap under Alternative 3, about 6,452 acres would be in active
allotments and 653 acres would be in a forage reserve allotment. Alternative 3 would
therefore result in an increase of 813 acres over Alternative 2 of overlap between domestic
sheep grazing in active allotments and mapped bighorn summer range, all in the Engine
Creek/Deer Creek Allotment. For the reasons stated above, we believe this increase in
overlap acres under Alternative 3 ultimately benefits bighorn sheep. This is because the
813 additional acres of overlap in this active allotment would be in an area judged to be
“Moderate Risk” for contact. Including these 813 additional acres in a “Moderate Risk”
area would allow the closing of about 19,891 acres in areas rated as “High Risk” under
Alternative 2.
To summarize the results in a different way, under Alternative 2 about 40,458 acres of
overlap would be in areas rated as “High Risk” for contact, there would be 0 acres in
areas rated as “Moderate Risk”, and 973 acres would be in areas rated as “Low Risk”.
Under Alternative 3, there would be 0 acres of overlap in areas rated as “High Risk” for
contact, there would be 6,132 acres in areas rated as “Moderate Risk”, and 35,298 acres
would be in areas rated as “Low Risk”.
The domestic livestock permittees and agency livestock permit administrator meet each
winter to discuss annual operating instructions for the upcoming grazing season. In
conjunction with this meeting, the agency wildlife biologist and CDOW staff will meet with
the permittee to review the effectiveness of project Design Criteria implementation and
any new bighorn sheep information obtained over the previous year. At this time, the risk
assessment rating for each allotment will be reviewed as necessary, and updated with
new information as appropriate. Discussion with permittees about management actions,
observations, and opinions are a critical component for finding consensus based solution
opportunities to new issues as they arise. These meetings will include staff from adjacent
land management administrative units, as necessary, to facilitate discussions of
opportunities for utilizing grazing options on adjacent units. The objective of these
discussions would be to explore mutually acceptable ways to reduce the risk of contact
between bighorn sheep and domestic sheep using a flexible adaptive approach to problem
solving, and to be more responsive to the management needs of livestock permittees and
the dynamic nature of a highly mobile wildlife species.
Annual reviews of risk assessment ratings and the potential for contact between domestic
and bighorn sheep may be necessary because the S33 Pole Mountain/Upper Lake Fork
bighorn sheep herd appears to be increasing in numbers and possibly expanding in
range. For this reason, the extent of occupied summer range may vary from one season to
the next, necessitating an adaptive approach to where and how domestic sheep are
managed on the landscape.
Wildlife staff of the FS/BLM will work with the local staff of the Colorado Division of
Wildlife to develop and implement a coordinated annual monitoring plan for bighorn
sheep in the upper Animas River basin. Given the designation by CDOW of the S33
bighorn herd as a primary (“Tier 1”) population ranked as a high priority for conservation
at a statewide level, it is logical for CDOW and BLM to place a greater emphasis on
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