A profit maximization model and an ARIMA model were developed to forecast water demand for broiler production. Broiler production decisions are made in three successive stages -- primary broiler breeding flock, hatchery flock, and finishing broiler production. The forecasted numbers of broilers from structural and ARIMA models depart significantly from a USGS physical model. Analysis indicates 15% slippage in water demand forecasting related to disregarding the role of economic variables. We also found that an appropriate lag structure can fully capture the information used in structural models, assuming no structural change.