Bonneville Power Administration is evaluating whether to purchase power from a proposed wind power development in Benton and Yakima Counties, Washington. The proposed Maiden Wind Farm is located in the Rattlesnake Hills northeast of the town of Sunnyside, Washington. The proposed development could be up to 494 MW with as many as 549 turbines and four met towers depending on factors such as turbine model selected and power purchase agreements.
Studies conducted for the project include fixed-point surveys which targeted raptors and large birds, paired-plots surveys which targeted breeding passerines in the study area, raptor nest surveys, vegetation/habitat mapping, and general wildlife observations. The principal goals of the baseline studies were to: (1) quantitatively describe the temporal and spatial use by birds of the study area; and (2) provide baseline information on avian species and their habitat sufficient to use in evaluating the probable impact of the development. Detailed study methodology of the surveys for each component is provided below in the text of the report.
Four basic habitat types (agriculture, steppe, riparian, and wetland) occur in the study area. The agriculture habitat type is comprised of one vegetation type, cropland, and makes up approximately 35% of the study area (6419 acres). The steppe habitat is comprised of four types, grassland steppe, shrub steppe, lithosol, and rock outcrop shrub. The steppe habitats combined make up approximately 64% of the study area (8527 acres). Riparian habitat was found in draws below springs and along Sulphur Creek. Riparian habitat comprised 1% of the study area (135 acres). The wetland vegetation type was a minor component of the study area and comprised <0.1% (3 acres) and is confined to springs and a fringe along Sulphur Creek.
Several avian species of interest (bald eagle, ferruginous hawk, merlin, loggerhead shrike, sage thrasher, and sage sparrow) were observed on or near the site outside of scheduled surveys when observers were traveling to or between points. Six species of mammals (coyote, mule deer, elk, porcupine, Townsend’s ground squirrel, and unidentified jackrabbit) and three species of reptiles (rattlesnake, short-horned lizard and yellow-bellied racer) were recorded in the study area during the studies. No federally listed threatened or endangered species were observed in the study area.