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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-110 The presence of transmission line structures, which could provide additional perch and/or nesting sites for avian predators, could negatively impact nearby prey species such as small mammals and avian species, particularly when the new structures are built in an area where perching opportunities currently do not exist (i.e., greater than 0.25 mile from existing structures or trees). Construction of Route Segment NNR-5 would require an estimated 16 new structures in a landscape dominated by low growing grasses and shrubs. An estimated 10 new structures would be located greater than 0.25 mile from an existing transmission line (Table 4.3-5). Within one mile of Route Segment NNR-5, potentially suitable habitat is present for 35 special status wildlife species that are possible, likely, or known to occur (Tables 3.3-2, 3.3-3, and 3.3-7). Potential impacts and RDFs to address them are discussed in Sections 4.3.3.1 and 4.3.3.2. Species or wildlife resources that have been documented at specific locations within one mile of Route Segment NNR-5 include a burrowing owl nesting site. A historic burrowing owl nesting site (last documented occupancy prior to 2000) occurs approximately 0.7 mile from Route Segment NNR-5. While this particular nest is not likely to have persisted to the present, it demonstrates potential for burrowing owls to nest within one mile of Route Segment NNR-5. Potential impacts would occur from disturbance during construction activities or from injury or mortality from vehicle strikes or interactions with other equipment used during construction, including mechanical disturbance or crushing of burrows. If an occupied burrowing owl nesting site is found within 0.25 mile of the proposed route, a seasonal restriction on construction would be enacted from March to August, within the 0.25-mile buffer. Additional RDFs to reduce impact on burrowing owls are described in Sections 4.3.3.1 and 4.3.3.2. Impact levels to burrowing owl are expected to be moderate for 0.6 mile. All habitat disturbance associated with Route Segment NNR-5 would be located within the Regularly Occupied Habitat MU for Sage-Grouse. Construction activities would disturb less than one percent of Regularly Occupied Habitat (Table 4.3-7). Anticipated ground disturbance includes 9.1 acres of suitable Sage-Grouse habitat (Table 4.3-8). With the implementation of RDFs (refer to Sections 4.3.3.1 and 4.3.3.2), habitat impact levels would be low for 0.1 mile and moderate for 1.7 miles. Existing perching, roosting and nesting sites for avian predators are available along Route Segment NNR- 5 from buildings, trees, and fences associated with developed areas and existing distribution and 230 kV H-frame transmission lines. Construction of Route Segment NNR-5 would require an estimated 16 new structures; approximately 10 (63 percent) would be located greater than 0.25 mile from an existing transmission line (Table 4.3-5). The estimated Sage-Grouse population range does not overlap Route Segment NNR-5 ROW corridor (Figure 3.3-4). No active leks are known to occur within four miles of Route Segment NNR-5 (Table 4.3- 6). With the implementation of RDFs (Sections 4.3.3.1 and 4.3.3.2), impacts to lekking Sage-Grouse associated with the construction of Route Segment NNR-5 is anticipated to be low for the entire length of the route segment (1.8 miles). 4.3.4.15 Route Segment NNR-6o/NNR-6u Route Segment NNR-6 is being considered as either an underground segment (NNR-6u) or as an overhead segment (NNR-6o). Undergrounding would create a larger area of ground disturbance than an overhead line would, because the overhead line would cause relatively little ground disturbance along the spanned areas between structures and the underground portion would require a continuous trench and a permanent access road. The Overhead Design Option would result in approximately 27.3 acres of long- term and 3.3 acres of short-term disturbance, while the Underground Design Option would cause approximately 50.9 acres of long-term disturbance and 6.6 acres of short-term disturbance resulting in nearly two times as much ground disturbance as the Overhead Design Option. For Route Segment