The D.C. Circuit denied the consolidated petitions for review of Federal Energy Regulatory Commission (FERC) orders approving a proposal by Southwest Power Pool, Inc. (SPP) to prospectively reclassify four transmission facilities in the Sunflower Zone from “Byway” status to “Highway” status, thereby shifting their remaining costs from local allocation to regional allocation. The court applied the Administrative Procedure Act’s arbitrary-and-capricious standard of review, noting that its scrutiny of FERC’s technical ratemaking judgments is particularly deferential. Under this standard, the court examined whether FERC examined relevant data and articulated a rational connection between the facts found and the choice made, rather than substituting its own judgment or determining if the decision was the “best” possible one. The court held that FERC’s reliance on the cost-causation principle—which requires rates to be just and reasonable and costs to be roughly commensurate with benefits—was supported by substantial evidence. The court rejected four specific challenges raised by petitioners: 1. **RCAR Analysis:** The court found it reasonable for FERC to approve facility-specific reallocation despite Regional Cost Allocation Review (RCAR) data showing the Sunflower Zone was a net beneficiary under the existing system. FERC correctly explained that RCAR is a “big picture” zonal analysis, whereas the proposal addressed specific facility imbalances; a favorable zone-wide ratio does not preclude correcting costs for individual facilities that are functioning as regional assets. 2. **Zone-by-Zone Benefit Analysis:** The court held that FERC was not required to conduct a granular, zone-by-zone assessment of benefits for all other SPP zones before reallocating costs regionally. The Highway/Byway framework itself allocates costs in broad strokes based on voltage and regional function, not with “exacting precision” or by tracing costs to specific entities. 3. **Order No. 1000 Compliance:** The court determined that FERC did not violate Order No. 1000’s ex ante cost-allocation requirement. While Order No. 1000 requires advance establishment of allocation methods, it does not bar Section 205 filings proposing rate changes when circumstances change. FERC adequately explained that the facilities’ usage had meaningfully changed due to increased wind generation, justifying the prospective adjustment without establishing a new standard process for future cases. 4. **Reliance on Technical Analyses:** The court found FERC’s reliance on SPP’s capacity, flow, and benefit analyses constituted substantial evidence. The court rejected petitioners’ objections regarding the methodology, noting that the inability to trace individual electrons does not invalidate modeling used to estimate generation sources, and that petitioners offered no competing data to undermine FERC’s findings. As a result of the denial, FERC’s orders approving SPP’s proposal stand, allowing the four facilities to be treated as Highway facilities for cost allocation purposes going forward, with costs borne regionally rather than locally.