This article presents a computer model for optimal planning of supply and distribution of water from open irrigation canal designed to support the manager of the irrigation system in decisions on the operational management. It optimizes the supply and distribution of water among users along the canal with a criterion minimum of operational water losses. The task of optimal operational planning of water allocation was solved using the method of integer linear programming. Computer application of the integer programming model was made using MS EXCEL. The use of the model is illustrated with an example of an irrigation canal with six lateral canals.