The Bureau of Land Management (BLM) has received a proposal from Solar Partners I, II, IV, and VIII, limited liability corporations formed by BrightSource Energy (BrightSource), to construct and operate an approximately 4073-acre solar thermal electric generating facility in San Bernardino County, California. The project would generate up to 400 megawatts (MW) of electricity using solar thermal technology. The project would occupy 4073 acres of federal lands managed by the BLM. The proposed project would consist of three separate generating facilities, each consisting of a field of heliostats (mirrors) reflecting solar radiation to the top of a 459-foot tall power tower received unit. Heated fluid within the power tower receivers would be used to boil water to generate steam, which would turn a turbine and generate electricity. The permanent ROW required for the heliostat fields and power towers would occupy approximately 3,670 acres. An additional 377 acres would be used to support a Construction Logistics Area, and for shared facilities such as an administration building, maintenance warehouse, substation, and groundwater supply wells. Approximately 24 acres would be used for a natural gas supply pipeline ROW, and for access roads. The proposed project would cause the surface disturbance of approximately 4,073 acres during construction. Two alternatives were considered in detail in the Draft Environmental Impact Statement (DEIS), which was published on November 9, 2009. These included the proposed project alternative, and the No Action Alternative, as required by the National Environmental Policy Act as a baseline against which other action alternatives can be analyzed. Under the No Action Alternative, the BLM ROW grant to construct and operate the facility would not be authorized. Consequently, the No Action Alternative represents the continuation of the existing conditions. The Supplemental Draft EIS (SDEIS) analyzes two additional alternatives to the proposed action; a reduced acreage alternative called the Mitigated Ivanpah 3 Alternative, and a reconfigured alternative called the Modified I-15 Alternative. The facility evaluated in each of these alternatives is a solar thermal electric generating facility with a generating capacity of 370 MW. The Mitigated Ivanpah 3 Alternative would be located entirely within the same property boundaries as the proposed project, but would occupy 3564 acres, a reduction of 12.5 percent. The Modified I-15 Alternative would also occupy 3564 acres, but the arrangement of one of the three power generating units would be reconfigured from the northern portion of the facility to the southern portion. Following the receipt of public comments on the SDEIS, BLM will select a preferred alternative in the Final EIS. .