This paper reports on findings from an irrigation water management study conducted in northern Oman. Although numerous descriptive accounts exist. quantitative research on the management and costs of irrigation water has been limited. As a result, very little is understood about the technical and economic performance of dominant irrigation practices within the agricultural sector. Based on research results from farmer surveys and direct monitoring of water use in the region, an attempt is made to provide a more thorough understanding of the costs to the farmer for irrigation water and related levels of water use performance. This paper argues that there is an inverse relationship between the cost to the farmer for irrigation water and the way that the water is managed. When access to ground water is available at relatively low costs, there is a tendency for the resource to he used excessively and managed inefficiently. This, in turn, results in serious environmental consequences and threatens the sustainability of irrigated agricultural production in the region. In such cases, alternatives must be sought by which unrestricted access to low cost water can be limited. The paper also discusses existing programs and suggests priorities which will serve lo facilitate effective development planning and the establishment of appropriate water management and irrigation programs.