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This document assesses the environmental impacts of the proposed remedial action at the Mexican Hat uranium mill tailings site located on the Navajo Reservation in southern Utah. The site covers 235 acres and contains 69 acres of tailings and several of the original mill structures. The Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, Public Law 95-604 (PL95-604), authorized the U.S. Department of Energy to clean up the site to reduce the potential health impacts associated with the residual radioactive materials remaining at the site. The U.S. Environmental Protection Agency promulgated standards for the remedial action (40 CFR Part 192). Remedial action must be performed in accordance with these standards and with the concurrence of the U.S. Nuclear Regulatory Commission and the Navajo Nation. The proposed action is to stabilize the tailings within the present tailings site by consolidating the tailings and associated contaminated soils into a recontoured pile. A radon barrier of compacted earth would be constructed over the pile, and various erosion control measures would be taken to assure the long-term stability of the pile. the no action alternative is also assessed in this document.