Vantage to Pomona FEIS Index 34 - Laserfiche WebLink

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Vantage to Pomona Heights Chapter 4 230 kV Transmission Line Project FEIS Environmental Consequences PAGE 4-122 each of the Action Alternatives, as well. The number of historic leks within four miles ranges from 10 historic leks near the three NNR Alternative design options, to 21 historic leks near Alternatives B, C, E, and G. Among the Action Alternatives, habitat connectivity between the YTC Sage-Grouse population and the Mansfield Plateau/Moses Coulee Sage-Grouse population appears to have the greatest potential where the NNR Alternative would be located—specifically where Route Segments NNR-6o/NNR-6u and NNR-7 are located. Local patterns of Sage-Grouse distribution suggest that Route Segment NNR-6o/NNR-6u is likely to be the most important connectivity zone, but the presence of two wind developments north of I- 90 reduces the connectivity value, according to the WHCWG model. In addition, the kernel density analysis shows a southeastward shift in the YTC Sage-Grouse population range and core population range since 1989. This shift in use could be associated with increased military training at YTC or, as Sage- Grouse populations have declined, Sage-Grouse are shifting into core, suitable habitat locations. Nevertheless, it appears that the entire stretch between Badger Pocket and the Columbia River could serve as valuable connectivity habitat. Because the proposed NNR Alternative closely parallels Pacific Power’s existing 230 kV transmission line as it crosses the identified connectivity area, the magnitude of its effect on Sage-Grouse movement would depend on a number of unknown variables, including the perception of the vertical transmission line structures by Sage-Grouse, and the potential for the structures to attract avian predators. The NNR Alternative may impede Sage-Grouse movement, but only to the extent that Sage-Grouse avoid the transmission line (refer to the Behavioral Avoidance of Infrastructure discussion above). The NNR Alternative - Underground Design Option could alleviate Sage-Grouse avoidance of a new transmission line at Route Segment NNR-6o/NNR-6u; however, two existing 500 kV and two existing 230 kV transmission lines, I-90, and the two existing wind developments would still be present on the landscape. Based on information provided by the kernel density analysis, it appears that use of the area north of the proposed NNR Alternative has been limited, even two decades ago when the YTC population was higher (over 400 birds). Of the three main Sage-Grouse connectivity zones identified by WHCWG, the one linking the YTC population with the reintroduced Yakama Indian Reservation population was the weakest. That connectivity zone would cross Alternatives A-H, with the most valuable zone crossing Route Segments 2b and 2c, before detouring around far to the west (or to the east) in order to connect with the habitat on the Yakama Indian Reservation. However, according to Robb and Schroeder (2012), development along the I-82 corridor “essentially isolates” habitat on the Yakama Indian Reservation from the YTC population and potential for movement between the two areas “looks dismal.” None of the proposed Action Alternatives are likely to impact Sage-Grouse connectivity to the south; given the existing barriers, it is unlikely that movement would occur between the YTC and Yakama Indian Reservation populations with or without any of the Action Alternatives. Overall impact levels for Sage-Grouse were estimated taking into account sagebrush-steppe habitat, crossings of Sage-Grouse population range, and proximity to active and inactive leks. None of the Action Alternatives had any miles of overall high impact levels or of no identifiable impact levels. The Agency Preferred Alternative and the NNR Alternative - Underground Design Option had the shortest distance classified as moderate impact (23.9 miles), followed by NNR Alternative - MR Subroute (24.3 miles). Miles of moderate impact for each of Alternatives A-H ranged from 35.1 miles for Alternative G to 45.9 miles for Alternative A. Even though Alternatives A-H passed through more degraded habitat than the three NNR Alternative design options, their much longer length, much greater overlap with occupied Sage-Grouse range, and closer proximity to more leks, indicate a greater overall impact on Sage-Grouse for Alternatives A-H. Among Alternatives A-H, Alternative A would have the greatest impact on Sage- Grouse, and Alternative G would have the least impact, though still larger than for any of the three NNR Alternative design options. While the NNR Alternative - MR Subroute would impact more miles than the NNR Alternative - Overhead Design Option or NNR Alternative - Underground Design Option most of the additional length is in a landscape that would yield a low level of impact on Sage-Grouse, resulting in modestly greater impact on Sage-Grouse than for the Agency Preferred Alternative. While the NNR