A prevailing impetus for this study stands on a concern on the development of efficient irrigation usage in upper Blue Nile Basin by measuring the present impact of Koga Irrigation Project (KIP) in Mecha Woreda, West Gojjam Zone, Amhara Region. Local development interventions in rural areas, through irrigation, have an important impact on the development of household livelihood in terms of reducing poverty incidence, increasing household income, and expanding household assets among others. But some of the findings, that concern on evaluation of the program, lack a strong conceptual framework for best analysis of impact of the intervention. And some lack methodological approaches. This may result in missing some important relations on the causal effects. The study believes sustainable livelihood approach as appropriate analytical and conceptual tool for development intervention impact through irrigation. Moreover the existing studies to investigate impact of irrigation on household had used different methodological approaches than propensity score matching. The study has two objectives; to evaluate the outcome of irrigation intervention on household livelihood.