This report contains the groundwater and surface water monitoring data that were obtained at the US Department of Energy (DOE) Y-12 National Security Complex (hereafter referenced as Y-12) in Oak Ridge, Tennessee, during calendar year (CY) 2000. These monitoring data were collected for the specific purposes of DOE Order 5400.1 site surveillance monitoring and exit pathway/perimeter monitoring, as described in the "Environmental Monitoring Plan for the Oak Ridge Reservation" (DOE 1996). Site surveillance monitoring provides data regarding the quality of groundwater and surface water in areas that are, or could be, affected by operations at Y-12. Exit pathway/perimeter monitoring provides data regarding the quality of groundwater and surface water where contaminants from Y-12 are most likely to migrate beyond the boundaries of the DOE Oak Ridge Reservation (ORR). The CY 2000 groundwater and surface water monitoring data presented in this report were obtained under the auspices of the Y-12 Groundwater Protection Program (GWPP), managed by Lockheed Martin Energy Systems, Inc. (LMES) (January-October, 2000) and by BWXT Y-12, L.L.C. (November-December, 2000), and the Water Resources Restoration Program (WRRP), which is managed by Bechtel Jacobs Company LLC. Combining the monitoring results obtained under both the Y-12 GWPP and the WRRP enables this report to serve as a consolidated reference for the groundwater and surface water monitoring data obtained at Y-12 during CY 2000.