NEPA--Environmental Assessment
NEPA--Environmental Assessment
NEPA--Environmental Assessment
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Silverton Grazing Risk <strong>Assessment</strong><br />
infer a lower risk rating. The fact that contact has not been observed, or a bighorn disease<br />
event has not been detected, does not imply a lower risk for such events happening in the<br />
future. For this reason, the allotment would still receive a rating of “High Risk”. A rating<br />
of “Moderate Risk” indicates that physical contact between bighorn and domestic sheep<br />
may occur at some point in the future, but effective separation may be achieved and/or<br />
maintained for many years. The risk of physical contact between bighorn and domestic<br />
sheep, with the subsequent potential for a bighorn disease outbreak, is thought to be<br />
substantially less than for allotments in the “High Risk” category. Factors that reduce the<br />
apparent risk of contact could include: application of herding techniques, bighorn sheep<br />
distribution patterns, presence of towns, presence of habitat features that act as barriers<br />
to bighorn sheep movement (Schommer and Woolever 2001). A rating of “Low Risk”<br />
indicates that physical contact between domestic and bighorn sheep is believed to be<br />
unlikely or irregular and unpredictable with the subsequent potential for a bighorn<br />
disease outbreak thought to be unlikely or unpredictable in the future under the current<br />
circumstances.<br />
Where overlap exists between active domestic sheep allotments and mapped bighorn<br />
sheep summer range or summer concentration areas (see Figures 1 and 2, below), the<br />
risk of contact between domestic sheep and bighorn sheep, with the potential for<br />
subsequent disease transmission, is “High” (see Figures 3 and 4, below). In vacant<br />
allotments, the risk of contact is “Low” when the allotment is vacant, but becomes “High”<br />
when the allotment is restocked.<br />
Where overlap exists between active domestic sheep allotments and mapped bighorn<br />
sheep summer range but domestic sheep are not actively grazed in that portion of the<br />
allotment, the risk of contact between domestic sheep and bighorn sheep, with the<br />
potential for subsequent disease transmission, may be either “High” or “Moderate”,<br />
depending on the circumstances. The risk level assigned to the allotment depends on<br />
whether or not there are mitigating factors such as distance to actively grazed portions of<br />
the allotment, terrain features providing separation, presence of broad bands of dense<br />
forest or presence of towns providing barriers to bighorn sheep movement, etc.<br />
A risk rating of “High” could be mitigated down to a rating of “Moderate” with the<br />
application of design criteria, changes in domestic sheep herding practices, not grazing<br />
certain portions of the allotment, application of design criteria designed to reduce the<br />
potential for contact, etc.<br />
After assigning an initial risk rating, additional factors from the list provided below were<br />
considered and a determination was made whether to change the initial risk rating.<br />
Factors such as the application of project design criteria differ between Alternative 2 and<br />
Alternative 3, leading to potentially different risk ratings for the same allotment among<br />
the two alternatives.<br />
D-10