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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-21 Approximately 0.9 acres of long-term disturbance and 1.8 acres of short-term disturbance in known occupied habitat are anticipated to occur along this route segment, less than 0.1 percent of the known occupied habitat of Columbia milkvetch in the region. WNHP indicates that a second Columbia milkvetch occurrence is located along a 0.6 mile section of Route Segment 2b. As all potential habitat was not surveyed, additional Columbia milkvetch occurrences could be present. Primary threats to this species are the continued degradation of habitat by military training activities and livestock grazing, increase competition by exotic invasive species, and loss of habitat by orchard development (WNHP and BLM 2005). For the proposed Project, direct and indirect impacts to Columbia milkvetch are similar to those described above for Nuttall’s sandwort. With the implementation of RDFs described above and the assumption that this occurrence will be spanned and avoided, Project construction, operation, and maintenance activities could impact individuals or habitat (moderate impact), but would not contribute a trend toward federal listing. 4.2.4.6 Route Segment 2c General Vegetation Construction of Route Segment 2c would result in long-term disturbance to approximately 34.3 acres of land (Table 4.2-4). The majority of long-term disturbance, 24.8 acres, would occur in areas classified as sagebrush/perennial grassland. Long-term disturbance would also occur to annual (9.4 acres) and perennial (0.1 acre) grasslands. Short-term disturbance would occur to approximately 22.1 acres of vegetation. General vegetation impacts are similar to those described above for Route Segment 1a/NNR- 1. Disturbance would be minimized by RDFs described above that are designed to reduce impacts to vegetation resources. RDFs include using existing public roads to access structure sites, minimizing blading and disturbance to plant communities, revegetating following construction, and implementing a Noxious Weed and Invasive Plant Management Plan. Refer to Section 2.3 - Required Design Features Common to Action Alternatives for a complete list and description of RDFs. Impacts for Route Segment 2c are anticipated to be: 7.6 miles of no identifiable, 6.0 miles of low, and 4.6 miles of moderate. Special Status Species and Priority Habitats No special status plant species or priority ecosystems are known to occur along Route Segment 2c (Table 4.2-5). Columbia milkvetch occurs within one mile of Route Segment 2c. No WNHP priority ecosystems are known to occur along Route Segment 2c. Fifty percent (0.1 acre) of federal lands within this route segment were surveyed for special status plants; however, the majority of Route Segment 2c is comprised of non-federal land (351.5 acres) and was not surveyed (Table 3.2-3). As not all land within the route segment was surveyed, impacts could occur to special status plant species. Long-term disturbance would occur to potential habitat for special status plants and include 8.0 acres of suitable, 9.5 acres of marginal and 5.2 acres unsuitable habitat. RDFs described above for Route Segment 1a/NNR-1 would also be implemented during construction and maintenance of Route Segment 2c to minimize impacts to special status plants. With the implementation of RDFs, impacts to special status plant species and potential suitable habitat are anticipated to include 7.6 miles of no identifiable, 6.0 miles of low impacts, and 4.6 miles of moderate impacts. 4.2.4.7 Route Segment 2d General Vegetation Long-term disturbance to approximately 36.6 acres of land would occur through the construction of Route Segment 2d (Table 4.2-4). The majority of disturbance, 34.1 acres, would occur in areas classified as