How to protect the environment without sacrificing the human environment and economy at the level of region is one of the most difficult issues of recent times. This paper focus on understanding dynamic relationships between regional economic system and environmental system, and presenting possible framework for finding policy leverages in dynamic interaction behaviors. The case, selected in this study, is Nakdong river regions case, which is related many meaningful issues about sustainable developments. Namely, two big metropolitan government and dwellers have different opinion with regard to construction of large scale Industrial park, drinking water supply, and environmental regulation and economic Investment, etc. For this research, we build an economic and environmental system Dynamics models consisting of three sectors: regional economy sector, river pollution and drinking water sector, environmental protection and investment policy sector. This paper deals with how to link policy leverage to causal loop structure for the sustainable development between two regions.