The project site is a series of grassland bench terraces on a bluff above the Pacific Ocean. Because the site has a long history of use for sheep grazing, the vegetation is mainly pasture grasses (64 percent of the site), with patches of mixed forest cover (26 percent), and wetlands (10 percent) in the ravine dividing the site. Because of the open nature of the site, the proposed arrangement of the wind turbines and relatively little need for site modification, there are few environmental concerns. The main concerns are the potential for bird collisions with the turbines and associated apparatus and threatened and endangered bird species. From literature reviews, site visits, and impact comparisons, the expected impacts of the project on vegetation, mammals, amphibians, reptiles, and fish have been determined to be minor (i.e., not significant). In order to predict the magnitude and importance of impacts on birds, a series of calculations were made using formulas from the literature to estimate bird kills from collisions with the wind turbines and associated apparatus. Based on stated assumptions, conservative estimates which would overestimate bird kills, were calculated for each turbine design alternative. Less than one-tenth of 1 percent of the vulnerable migrating bird population was determined to be subject to death by collision. Thus, impacts to birds were also determined to be insignificant. The other major concern is the potential impacts of the project on five species of birds from the area that are recognized as threatened or endangered. The site provides no unique or especially important habitat for any of the five species. The likelihood of project impacts to any of them is low. The potential level of impact is also low, and, therefore, the impacts are not significant. Impacts of the three alternatives are compared in tabular form and conclusions are drawn on the significance of the impacts. Since none of the alternatives appear to have significant impacts, mitigation measures are discussed more in terms of practices or actions which could or would reduce impacts.
Cape Blanco Wind Farm Feasibility Study Technical Report No. 11: Terrestrial Ecology
Title: Cape Blanco Wind Farm Feasibility Study Technical Report No. 11: Terrestrial Ecology
April 01, 1986
Portland General Electric Company (1986). Cape Blanco Wind Farm Feasibility Study Technical Report No. 11: Terrestrial Ecology. Report by Bonneville Power Administration and US Department of Energy (DOE). pp 66.