This impact analysis employs BLM trail management guidelines (BLM 1986b) to determine the impacts to NHTs and Other Historic Trails from the management of other resources, as described in this RMP. Other Historic Trails are trails eligible for listing on the NRHP, whether or not they have been listed. Completion of the evaluation step of Section 106 compliance may be necessary before moving forward with an undertaking that impacts a trail. Trails will be evaluated for eligibility based on the guidelines provided in the 1986 trails management guide, as interpreted in light of contemporary understanding of eligibility criteria.
Methods and assumptions used in this impact analysis include the following:
Protection of NHTs and Other Historic Trails and related sites occurs in accordance with federal laws and BLM regulations and agreements, including the BLM National Programmatic Agreement (BLM, ACHP, and National Conference of State Historic Preservation Officers 1997) and the Wyoming State Protocol (BLM and Wyoming SHPO 2006), regardless of whether the trails are specifically identified in the RMP.
Direct and indirect impacts can result from a variety of natural and human-caused events, such as those that physically alter, damage, or destroy all or part of the trail; improve access, bringing increased use to an area, altering characteristics of the surrounding environment that contribute to the trail’s importance; the introduction of visual or audible elements out of character with the trail or that alter its setting; and neglect of the trail to the extent that it deteriorates or is destroyed.
The intensity of surface disturbance by alternative as identified in Appendix T equates to levels of development and, in turn, increased access to public lands.
The BLM looks favorably at opportunities to cooperate with private landowners to minimize or eliminate disturbance to NHTs and Other Historic Trails.
Recognizing that historic trails often comprise numerous routes rather than a single trace, all protective zones begin at the outer edges of trails rather than at a centerline, which is difficult to define.
Certain projects, due to size or topography, may require consideration of visual intrusions into the setting beyond the foreground or middle-ground zones to become consistent with the modern understanding of impacts, and to comply with Section 106 of the NHPA.