3.6.3 Cumulative Environmental Effects Related to Botanical Resources

of the Project does require impacting isolated limber pine tree occurrences, this impact could come in the form of indirect impacts such as tree trimming and tree limb removal, a direct impact of full tree removal, or a combination of these depending on site conditions and Project requirements. Black Canyon will work with the BLM during final design to site the location of temporary disturbance areas to limit impacts to on old growth trees and BLM sensitive species, including limber pine, to the extent possible. Because limber pine is a primary constituent of Rocky Mountain Limber Pine-Juniper Woodland which is mapped by the GAP/Landfire habitat map outside of the botanical study area (USGS 2011), and over 2,000 occurrences of this species have been documented in the past 50 years (Intermountain Region Herbarium Network 2022), it is not expected that impacts to this species in the botanical study area would jeopardize the continued existence of this species.

Black Canyon intends to minimize impacts to Ute ladies’-tresses habitat, persistent sepal yellowcress, and limber pine to the maximum extent practicable. Additionally, Black Canyon intends to mitigate for displacement and disturbance of vegetation through development of a Habitat Restoration, Reclamation and Enhancement Plan. This plan could incorporate mitigation for the loss of Ute ladies’-tresses habitat and individuals, Rocky Mountain Foothill Limber Pine-Juniper Woodland and limber pine individuals, as well as persistent sepal yellowcress individuals. Thus, the Project is not expected to have significant impacts to rare, threatened, and endangered plants.

Table 3.6-5. Temporary and Permanent Disturbance within Limber Pine Habitats

Permanent Disturbance Areas1

Feature

Underground Surface

Total Permanent Disturbance Acres

24.21

84.83

109.05

Temporary Construction Disturbance Area2

Surface 102.63

Total Impacted Area 211.68 1. Surface and underground impacts. Areas that are permanently disturbed and within the FERC Project Boundary. 2. Temporary during construction and will be revegetated after construction.

As noted in Table 3.2-1, the geographic scope for botanical resources is the HUC-8 watersheds in the Project vicinity since impacts within a HUC-8 watershed sufficiently accounts for impacts on vegetation (including special status species) that would be directly affected by construction activities and for indirect impacts such as changes in habitat availability and displacement of transient species. The HUC-8 watersheds that comprise the geographic scope are the Pathfinder-Seminoe Reservoirs watershed (HUC 10180003)

and the Medicine Bow watershed (HUC 10180004). As detailed in Table 3.2-2, there are six projects that occur within the geographic scope for botanical resources: 1) WPCI Project, 2) Two Rivers Wind Energy Project, 3) Lucky Star 1 Wind Project, 4) Gateway West Transmission Line Project, 5) Gateway South Transmission Line Project, and 6) Rock Creek Wind Energy Center.

Issues Identified for Analysis

Reasonably foreseeable future actions with potential to impact vegetation include actions that would remove vegetation through surface-disturbing activities. It should also be noted that most BLM-managed lands in Wyoming have been and continue to be used for grazing. Grazing impacts depend on vegetation type and how that grazing allotment has been managed. On BLM-managed lands, managers are required to monitor rangeland health and manage that grazing to meet established rangeland health standards and guidelines (BLM 2020b). Black Canyon would comply with BMPs and reclamation guidelines to minimize impacts to rare and unique vegetation types, important, and special-status plant species.

The susceptibility of an area to colonization by invasive species increases with vegetation removal and soil disturbance, both of which would occur with Project construction. Cumulative effects on botanical resources are possible as a result of increased potential for spread of noxious weeds. However, weed populations in the Project vicinity are driven by regional-scale invasions and land use patterns rather than infrastructure projects specifically. The Project’s contributions to noxious weed distributions would be limited by BMPs and the implementation of a Noxious Weed Management Plan consistent with BLM noxious weed management guidelines.

Removal of vegetation would occur with Project construction of access roads, transmission towers, the upper reservoir, and other permanent Project structures. It is not expected that implementation of the Project will results in loss of native upland vegetation communities.

Permanent loss of vegetation occurs with construction of features such as roads and buildings (or similar large man-made structures). Temporary removal or crushing of vegetation does not results in a total loss of vegetation; however, revegetation of these areas often results in vegetation communities the differed from those that occurred predisturbance. Vegetation communities adjacent to disturbed areas also may differ in structure and compositions form those that occurred pre-disturbance, as soil disturbance and the transportation of seeds of non-native or invasive species by humans and/or livestock may have increased the likelihood of these areas being invaded by non-native species.

Results

The removal of vegetation, disturbance of soils, and transportation of seeds by humans and/or livestock may increase the likelihood of noxious weed invasion and spread in the area. Past actions that required the removal of vegetation and disturbance of soil likely resulted in the introduction of some noxious weeds. Present actions that require the removal of vegetation and disturbance of soils may also contribute to the introduction and