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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-108 4.3.4.13 Route Segment NNR-4o/NNR-4u Route Segment NNR-4 is being considered as either an underground segment (NNR-4u) or as an overhead transmission segment (NNR-4o). Undergrounding construction would create a larger area of ground disturbance than overhead construction would because the overhead line would cause relatively little ground disturbance along the spanned areas between structures while the underground portion would require a continuous trench and a permanent access road. The Overhead Design Option would result in approximately 21.4 acres of long-term and 1.5 acres of short-term disturbance, while the Underground Design Option would cause approximately 43.7 acres of long-term disturbance and 2.9 acres of short-term disturbance resulting in more than two times as much ground disturbance as the Overhead Design Option. For Route Segment NNR-4o, permanently disturbed areas would include 10.8 acres of sagebrush/perennial grassland and 9.2 acres of sagebrush/ annual grassland (Table 4.3-4). Undergrounding Route Segment NNR-4u would increase the permanently disturbed areas to 24.7 acres of sagebrush/perennial grassland and 17 acres of sagebrush/annual grassland. The remaining 1.4 acres of long-term disturbance for NNR-4o, 2.0 acres for NNR-4u, and all short-term disturbance (1.5 acres for NNR-4o and 2.9 acres for NNR-4u) consists of annual grassland and noxious weeds, other shrublands, and perennial grassland. RDFs would be implemented to minimize habitat loss and degradation, as described in Section 4.3.3.1. For either design option, impact levels to habitat are expected to be low for 0.4 mile and moderate for 4.1 miles (other shrublands for 0.1 mile, sagebrush/perennial grassland for 2.3 miles, and sagebrush/annual grassland for 1.7 miles). The presence of new 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-4o would require an estimated 35 structures; none of the new structures would be located greater than 0.25 mile from an existing transmission line (Table 4.3-5). The Underground Design Option, NNR-4u, would need to be overhead for a short-stretch as it crosses I-82. This would require two transmission towers, all within 0.25 mile of existing structures. In addition, at each of the four transitions between aboveground and underground transmission, a transition station would be required resulting in approximately five acres of disturbance at each transition station. Within one mile of Route Segment NNR-4o/NNR-4u, potentially suitable habitat is present for 44 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-4o/NNR-4u include a cliff band with a high concentration of nesting raptors, several golden eagle nests within one breeding territory, a historic ferruginous hawk nest, a historic burrowing owl nesting site, and winter range for bighorn sheep. Cliff bands occur along Lmuma Creek, within one mile of Route Segment NNR-4o/NNR-4u; the cliffs attract high concentrations of raptors, including prairie falcons (not a special status species, but sensitive to nest disturbance) and several golden eagle nests associated with one breeding territory, approximately 0.6 mile from the route segment. A historic ferruginous hawk nest was documented in 1994 on top of a six-foot rock outcrop approximately 0.9 mile from the route segment. Cliffs would be spanned, thus, avoiding direct disturbance to the habitat. Burrowing owl surveys in 2000 located one burrowing owl nesting site within the Project area, approximately 120 feet from Route Segment NNR-4. Within the breeding season, construction would be avoided within species-specific active raptor nest buffers to avoid disturbing nesting birds (0.5 mile for golden eagle and ferruginous hawk, 0.25 mile for prairie falcon, and burrowing owl; see RDFs in Chapter 2). Impact levels on golden eagles are anticipated to be moderate for 0.5 mile, impact levels on ferruginous hawks are expected to be moderate for 0.3 mile, and impacts on burrowing owl are expected to be moderate for 2.0 miles.