This study proposes a fuzzy sets approach for estimating irrigation efficiency of limited water resource area. Genetic algorithm technique was applied to calibrate membership function condition of fuzzy sets model. The proposed model considered the total available water resource and the farmer participation of water resource management as the input variables. The approach model was applied to determine the irrigation efficiency of the Nong Wei Irrigation Project (in the Northeast region of Thailand). Results showed that the fuzzy sets model can be used to estimate the irrigation efficiencies, given the total available water resources and the farmer participation. Furthermore, the results indicated that the farmer participation in water resource management can be calculated via the proportion of seasonal required-area and the overall land area of the irrigation project.