Land use/cover in Northeast China went through extensive changes during the 1990s. This report explores the interaction between these changes and the environment, and the implication of these changes for rational allocation of water resources. Two maps of land use/cover produced from 1990 and 2000 Landsat TM satellite images were overlaid in Arc Info to reveal changes in land cover. Results indicate that farmland and grassland decreased by 386,195 and 140,075 ha, respectively, while water, built-up areas, and woodland increased by 238,596, 194,231, and 192,682 ha, respectively. These changes bore a mutual relationship with the environmental change. On the one hand, climate warming made some of these changes (e.g., conversion of woodland and grassland to farmland) possible. On the other hand, the changed surface cover modified the local climate. These changes, in turn, caused severe environmental degradation and increased flooding. The change between dry field and rice paddy, in particular, raised severe implications for the proper allocation of limited water resources in the Northeast. Efforts are needed to coordinate their rational allocation to reap maximum and sustainable return over the entire area, not just in some localities. Results obtained in this study should be of interest to the international audience of Environmental Management in that they highlight the interactive nature of human activities and the environment and the off-site impact of these activities on the environment.