Morteza Anoushirvani - Administrator (Chief Executive office), City of portland bureau of water works, ۱۱۲۰sw ۵th Avenue ۶th floor, portland, oregon ۹۴۲۰۴, usa
Azad Mohammadi - Senior Engineer City of Portland abd Bureau of water Works , ۱۱۲۰ SW ۵th, Avenue ۶th Floor , portalnd , Oregon ۹۷۲۰۴, USA

The initial report of the intergovernmental panel on Climate Change (IPCC 1996) and those that have followed (IPCC 2001) conclude that our climate is change. On of the most important consequences of climate change is its impact on the world’s fresh water supplies, caused by increased temperatures changed precipitation , and shifts in the historic hydrologic states has been the focus of interest for a number pf years (Hahn et al., 2001, Lettenmaier et al. 1999 Wood et al . 1997) . pacific Northwest basins hold particular intrigue because of the interplay of two factors, rainfall and temperature . all of the major water in the late spring and early summer. In addition , climate change can alter the demand for water . with demands increasing during dry, warm periods and decreasing during cool, wet periods . these change in the availablility of and demand for supply will impact munipalities that are charged with providing safe and reliable existing customers and their planning for the future. New sources of water may be required , and the evaluation of these new sourves should consider potential climate change.