The Burdekin delta in north Queensland is the most important area for irrigated sugarcane production in Australia. Conjunctive use of groundwater and surface water is a common practice in this area, and requires that the groundwater systems be carefully managed to ensure the long-term economic and environmental well being of the whole region. Management of the system requires that sufficient water be provided to the crops grown in the area while maintaining sufficient pressure in the groundwater system to minimise potential problems associated with salt water intrusion. A groundwater management model is being developed to help address these issues by simulating the behaviour of the groundwater system in response to various management strategies. The output from the groundwater model along with data from a plant growth simulation model has been used as input to a regional mathematical programming model, to examine the economic and environmental impacts of various groundwater management strategies in the delta region.