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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-35 Underground Design Option Construction of NNR-6u would result in approximately 50.9 acres of long-term disturbance to vegetation. Long-term disturbance would occur primarily in sagebrush/perennial grassland (50.1 acres), with the remaining disturbance occurring in 0.6 acre of forbs and 0.2 acre of perennial grassland. Approximately 6.5 acres of vegetation would be disturbed on a short-term basis. In addition to impacts described above in Section 4.2.3, additional underground construction disturbance would occur through open cut trenching and excavation for the installation of underground duct bank, splice vaults, and construction of access roads and temporary work sites. RDFs described above for Section 4.2.3 and for Route Segment 1a/NNR- 1 would also be implemented for the Route Segment NNR-6u. Following the implementation of RDFs, long-term impact levels to vegetation for NNR-6u would include 0.9 mile of low and 5.6 miles of moderate impacts. Special Status Species and Priority Ecosystem No federally listed plant species or priority ecosystems are known to occur along Route Segment NNR- 6o/NNR-6u (Table 4.2-5). No special status plants were documented during special status plant surveys conducted for the proposed Project within Route Segment NNR-6o/NNR-6u. WNHP data shows an occurrence of Suksdorf’s monkeyflower (Erythranthe suksdorfii) intersects this route segment near its eastern terminus and that beaked cryptantha, caespitose evening-primrose, coyote tobacco (Nicotiana attenuata), longsepal globemallow (Iliamna longisepala), and snowball cactus all are known to occur within one mile of Route Segment NNR-6o/NNR-6u. Due to route adjustments made following the special status plant surveys, none of Route Segment NNR-6o/NNR-6u was surveyed for special status plants, which is comprised entirely of federal land (117.1 acres; Table 3.2-3). Overhead Design Option With Route Segment NNR-6o, long-term disturbance to special status species potential habitat would occur to 6.4 acres of suitable and 0.2 acre of marginal habitat. RDFs described above for Route Segment 1a/NNR-1 and Impacts Common for All Route Segments (Section 4.2.3) would be implemented during construction and maintenance of Route Segment NNR-6o 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 0.9 mile of low impacts and 5.6 miles of moderate impacts for Route Segment NNR-6o. Underground Design Option With the Underground Design Option (NNR-6u), long-term disturbance to potential habitat for special status species would occur to 10.0 acres of suitable and 0.2 acre of marginal habitat. RDFs described above for Route Segment 1a/NNR-1 and Impacts Common for All Route Segments (Section 4.2.3) would be implemented during construction and maintenance of Route Segment NNR-6u to minimize impacts to special status plants. Suksdorf’s monkeyflower is known to occur near the eastern end of Route Segment NNR-6u, in approximately the same location where a five-acre transmission transition station would be needed. If preconstruction surveys document any special status plants within trenching or transition stations, adjustments would be made to avoid or minimize impacts to these species where practicable. If avoidance is not possible, impacts to special status plant species and habitat would be minimized through the implementation of RDFs such as: implementing measures identified in the Reclamation, Re- vegetation, and Monitoring Plan; in coordination with the land management agencies, salvaging and respreading topsoil surrounding the plants to preserve the seed bank and localized species habitat conditions; using weed-free borrow material and soil; and implementing a Noxious Weed and Invasive Plant Control Plan.