New benefit-cost calculations for the Marble Canyon Project, based on current arguments on its economic feasibility. The main differences between these and the ones of the Bureau of Reclamation concern the use of the same rate of return on capital for both project and alternative, and the location of the latter at one, not two load centers. Since current prices show that a nuclear alternative would cost less for generating peaking power, the project is not economically justified. Nuclear costs are developed for three cases. For each, the benefit-cost ratio is less than 1:1. The major assumptions are enumerated, and judged biased in favor of the Project.