Today water supply issue in large cities seems to be a big problem. This becomes more important with population growth and urbanization extension. To cope with this problem lots of irrigation and drainage projects have been implemented and operated that subsequently many socio- economic and cultural effects have been brought to the areas . The objective of the present study is to survey the socio - economic and environmental effects of Taleghan dam to compare the two periods before and after the dam construction. The needed data have been gathered by use of a questionnaire and by interviewing 400 samples in the irrigation and drainage network’s region of Taleghan Dam, and encoded questions and outcome data have been analyzed in spss and lisrel software. The results showed an economic development in the region, but some factors like, lack of trust, lack of economic advantages and deficiency of facilities, decrease villagers’ willingness to invest. 63.3% of region’s environmental pollution has been increased mainly by the tourists. Not only is there no increase in Water sources but also they have been decreased. 98% of individuals declared that the people were not questioned in construction projects. About the coefficient of dam’s effect on region’s socio- economic and environmental development, the villagers have declared that the dam construction had no positive effect on region’s development.