The Rio Mesa Solar development--a downsized and retooled project initially proposed as a 5,750-acre, 750 MW plant--passed the latest in a series of regulatory hurdles at the California Energy Commission. According to a preliminary staff assessment, the Rio Mesa Solar Electric Generating Facility, which is a third smaller, would comply with all applicable laws, ordinances, regulations and standards and cause \u201cless than significant\u201d environmental impacts. \u201cBased on a review of the original and amended [application for certification], staff concludes that the project would be built and operated in a manner consistent with industry norms for reliable operation,\u201d the 686-page assessment released Sept. 28 reads. The Rio Mesa project is owned by BrightSource, which filed its application with the Energy Commission in October 2011. In May, BrightSource filed a letter with the CEC notifying it that the project was being retooled for the sake of \u201cenvironmental enhancements.\u201d The new configuration consists of two 250 MW solar concentration thermal power plants--instead of the original three--both situated on the Palo Verde Mesa, about 13 miles southwest of Blythe in Riverside County. The two plants, which would generate a combined 500 MW, would sit on 3,805 acres of private land leased from the Metropolitan Water District of Southern California. Each plant would utilize a solar power boiler located on top of a 750-foot high concrete tower surrounded by fields of about 85,000 heliostat mirrors, which would focus solar energy on the boiler. The facility\u2019s designed to interconnect with the Southern California Edison grid through a new 220kV line that would be built as part of the project. It would run north about 10 miles to link with the Colorado River Substation. Although the Energy Commission staff report concluded that the project would be compliant in most areas, it also highlighted six technical areas where the project would create issues that need to be resolved. These are in the areas of geology and paleontology, soil and surface water, traffic and transportation, transmission system engineering, water supply, and visual resources. In each area, there\u2019s either a significant, unmitigated impact, non-compliance with applicable laws and rules, or outstanding issues that have to be resolved through additional data, further discussion, and\/or analysis, according to the staff report. Among the concerns are the lack of a plan for storm water erosion and sedimentation impact management; a plan for dealing with the impacts of glint caused by the arrays; and other unavoidable adverse direct visual impacts. The assessment isn\u2019t a final decision and doesn\u2019t contain final findings by staff related to the environmental impacts or the project\u2019s compliance with local, state, and federal legal requirements. It does, however, reveal how, and if, the project has met state licensing guidelines thus far. It also serves as a precursor to the final staff assessment, which acts as staff\u2019s testimony in evidentiary hearings to be held later this fall by a committee. As part of the process, the committee\u2019s obligated to hold evidentiary hearings and issue a recommended decision to the full commission. Following one or more public hearings on the matter, expected to occur next spring, the full Energy Commission makes a final decision, something that could occur in the summer of 2013 at the earliest. According to BrightSource, if all goes according to the current schedule, the project could be operational by 2016.