Technical Abstract: Practical, automatic real-time control of surface irrigation faces several difficult constraints. Most surface irrigation water supplies must be scheduled in advance and use must be coordinated with other demands. Either the supply systems must be able to adapt to the occasional demand of automatic systems, or the application systems must communicate their needs to the supply system with the required lead time. Surface irrigation performance depends strongly on soil surface and infiltration characteristics. These parameters normally vary widely spatially and from irrigation-to-irrigation, and are difficult to predict. Performance monitoring and system adjustment is usually required to insure good performance, especially during early season irrigations. Automatic real-time control systems thus must include some type of performance feed-back control. This paper discusses the severity of these constraints and possible solutions for the several types of surface irrigation systems and water supply conditions.