The subject of this paper is to suggest a methodology to evaluate the economic value of water which can be used as a basis for water pricing. The methodology involves the use of agricultural sector models incorporating water as a scarce input. The economic value of water for different land types, regions and crops are estimated from the shadow prices of water and irrigated land constraints. After a theoretical discussion, the paper will also present the results of such a model applied to the South-eastern Anatolia Project (GAP) Region in Turkey, which is one of the world's largest irrigation and integrated regional development projects. Changes and differences in land values as a result of irrigation will be presented towards the estimation of the economic value of water