Potential for change in the mix of irrigated enterprises was estimated for a catchment in the Shepparton irrigation region using linear programming. The model allocated resources to maximise net income in each of the next five decades as if the catchment were one farm. Change was driven by price trends and productivity and constrained by water resources, land capability and investment capital. On the basis of the assumptions implicit in the model and sensitivity testing carried out, it appears more likely that there will be a rapid decline in irrigated cropping and pasture based meat production in conjunction with a significant increase in irrigated dairying in the first two decades, followed by an interchange of resources between dairying and new horticulture with the catchment dominated by horticultural enterprises by year 50. A workshop has demonstrated the usefulness of the approach for assisting catchment management agencies and policy makers understanding the implications of different price, productivity and irrigation water allocation scenarios for sustainable economic growth and natural resource management. While improvement to the model is readily achievable, the marginal utility of complex sophistication is questionable.