This report presents an evaluation of the groundwater and surface water monitoring data obtained during calendar year (CY) 2000 from sampling locations in the Chestnut Ridge Hydrogeologic Regime (Chestnut Ridge Regime). The Chestnut Ridge Regime encompasses several hazardous and nonhazardous waste management facilities associated with the U.S. Department of Energy (DOE) Y-12 National Security Complex (hereafter referenced as Y-12) southeast of Oak Ridge, Tennessee (Figure A.1). Prepared by the Y-12 Groundwater Protection Program (GWPP), this monitoring data evaluation report addresses applicable provisions of DOE Order 5400.1 -- General Environmental Protection Program -- that require: (1) an evaluation of the quantity and quality of groundwater in areas that are, or could be, impacted by Y-12 operations, (2) an evaluation of the quality of surface water and groundwater where contaminants from Y-12 facilities are most likely to migrate beyond the DOE Oak Ridge Reservation (ORR) property line, and (3) an evaluation of long-term trends in groundwater quality at Y-12. The following sections of this report contain relevant background information (Section 2.0); describe the results of the respective data evaluations required under DOE Order 5400.1 (Section 3.0); summarize significant findings of each evaluation (Section 4.0); and list the technical reports and regulatory documents cited for more detailed information (Section 5.0). Illustrations (maps and trend graphs) and data summary tables referenced in each section are presented in Appendix A and Appendix B, respectively.